Comprehensive Truck Size and Weight Limits Study - Compliance Comparative Analysis Technical Report

Appendix A: Revised Compliance Desk Scan

CHAPTER 1 – INTRODUCTION

1.1 Purpose

This report presents a revised version of the Desk Scan (Subtask V.D.2) developed to support the Compliance Comparative Analysis (Task V.D) of the 2014 Comprehensive Truck Size and Weight Limits Study (2014 CTSW Study). This revised Desk Scan addresses the recommendations made by the National Academy of Science (NAS) Peer Review Panel concerning the originally submitted version of this scan.

The purpose of the revised Desk Scan is to:

Reorganize and enhance the original Desk Scan; and
Add any additional, relevant content that may have been identified since the submission of the original Desk Scan.

Specifically, the NAS Peer Review Panel recommended that the original Desk Scan be reorganized to address four issues:

Analysis methods and the state of the practice in modeling the impacts of truck size and weight (TSW) enforcement on compliance;
Identification and critique of data needs concerning TSW enforcement costs and effectiveness;
Assessment of the current state of understanding of the impact and needs for future research, data collection, and evaluation in the area of TSW enforcement; and
Quantitative results of past TSW enforcement studies.

1.2 Approach

To address these issues, the scan involves a comprehensive and review of literature regarding:

Needs and traditional approaches for TSW enforcement, and the impacts of regulatory changes on enforcement programs;
Enforcement costs and benefits;
The effectiveness of TSW enforcement;
The application and performance of TSW enforcement and compliance technologies; and
Alternative approaches for achieving compliance.

The literature search includes documents published from around the world since 2000, supplemented by key historical material. Approximately 60 documents are cited in this scan; these are sourced from: (1) engineering and scientific periodicals and journals; (2) conference proceedings; and (3) readily-available government and industry reports. Specific resources include:

Transportation Research International Documentation (TRID)
American Society of Civil Engineers
University of Michigan Transportation Research Institute Library
University of Manitoba Transport Information Group Library
ScienceDirect
NRC Research Press
Transportation Association of Canada
Heavy Vehicle Transport Technology Proceedings
Federal Highway Administration (FHWA) library
American Transportation Research Institute library
National Transport Commission (Australia) library
Australian Road Research Board library

A list of key documents follows:

Comprehensive Truck Size and Weight Study by the U.S. Department of Transportation (USDOT), 2000 (2000 CTSW Study)
Relevant special reports by the Transportation Research Board (TRB), namely Special Report 267 Regulation of Weights, Lengths, and Widths of Commercial Motor Vehicles and Special Report 225 Truck Weight Limits: Issues and Options
Recent TSW reports conducted in Maine, Vermont, Wisconsin, and Minnesota
Moving Freight With Better Trucks by the International Transport Forum
NCHRP Web Document 13 entitled Developing Measures of Effectiveness for Truck Weight Enforcement Activities
National Heavy Vehicle Enforcement Strategy Proposal by the National Transport Commission (Australia)

The scan emphasizes the enforcement of TSW limits; however, distinguishing enforcement activities concerning TSW from those directed at safety or credentials regulations was not always possible. Therefore, the review includes findings relevant to the general task of enforcing truck operations when these findings are also applicable to the enforcement of TSW limits.

1.3 Organization of this Report

This report synthesizes the literature concerning the costs and effectiveness of TSW enforcement from a programmatic perspective. Following this introduction, the report includes three chapters (organized as per the NAS Peer Review Panel recommendations):

Chapter 2 provides a synthesis of analysis methods, which encompass the state of the practice in understanding and modeling the impacts of TSW enforcement on compliance.
Chapter 3 provides an assessment of future research and data needs concerning TSW enforcement costs and effectiveness. (This chapter provides an integrated response to the second and third issues identified by the NAS Peer Review Panel.)
Chapter 4 synthesizes quantitative results of past TSW enforcement studies.

In addition to these three chapters, this report contains one addendum (Addendum A) which summarizes findings concerning alternative approaches for achieving compliance—principally those adopted in Australia. This topic falls outside the scope of the recommended issues to be addressed in this revised Desk Scan, yet provides context to its main findings. Finally, a complete list of references cited in this report is provided.

CHAPTER 2 - Synthesis of Analysis Methods

This chapter summarizes three categories of enforcement program analysis methods evident in the literature: (1) performance-based methods, (2) empirical methods, and (3) meta-analysis and survey-based methods.

2.1 Performance-Based Methods

The literature contains several documents that discuss the application of performance-based methods to the design, implementation, and evaluation of TSW enforcement programs.

Hanscom (1998, pp. 3, 7) recognizes the need to develop performance measures to support better analysis and understanding of the cost and effectiveness of enforcement programs. This report states that “the effect of truck-weight enforcement programs is not known in terms of: (1) actual impacts on weight-law compliance, (2) effect on safety of truck operations, (3) pavement service life effects, or (4) cost-effectiveness of enforcement activity.” Thus, Hanscom develops performance measures for truck weight enforcement activities. The focus of the research is to identify quantifiable measures that reflect the goals of an enforcement program (such as infrastructure protection) rather than using traditional indicators such as the number of trucks weighed, the number of violators detected, or the amount of fines collected. Initial development of candidate measures involved a survey of literature and state agencies, and the ranking of candidate measures in terms of: practicality of application, measurement reliability, support of statewide random sampling, absence of enforcement-induced bias, data collection methods capability, sensitivity to infrastructure damage, and applicability to data collection future technology. Candidate measures were then empirically validated using four independent field tests to determine the sensitivity of the measures to an imposed enforcement activity relative to baseline enforcement conditions. The validation revealed the weight enforcement program performance measures defined below:

“Gross weight violation, proportion: The fraction (or percentage) of the total observed truck sample which exceeds the legal gross weight limit.
Gross weight violation, severity: The extent to which average measured gross weights for the observed sub-sample of gross weight violators exceeds the legal gross weight limit.
Single-axle weight violation, proportion: The fraction (or percentage) of the total observed truck sample with one or more axles which exceeds the legal single-axle weight limit.
Single-axle weight violation, severity: The extent to which average measured single-axle weights for the observed sub-sample of single-axle weight violators exceeds the applicable legal limit.
Tandem-axle weight violation, proportion: The fraction (or percentage) of the total observed truck sample with one or more tandems which exceeds the legal tandem-axle weight limit.
Tandem-axle weight violation, severity: The extent to which average measured tandem-axle weights for the observed sub-sample of tandem-axle weight violators exceeds the applicable legal limit.
Bridge formula violation, proportion: The fraction (or percentage) of the total observed truck sample which exceeds the legal Bridge Formula weight.
Bridge formula violation, severity: The extent to which average measured Bridge Formula weights for the observed sub-sample of Bridge Formula violators exceeds the legal weight.
Excess ESALs [equivalent single axle loads], proportion: The fraction (or percentage) of the total observed truck sample exhibiting Excess ESALs; i.e., ESALs attributable to the illegal portion of the individual single- or tandem-axle group.
Excess ESALs, severity: The average value of Excess ESALs observed for the truck sub-sample exhibiting Excess ESALs.”

Since Hanscom’s work, several studies have advocated for the use of performance measures to analyze the cost and effectiveness of enforcement programs:

URS (2005, pp. 56-58) describes what a performance-based approach to enforcement would involve and makes the distinction between inputs, outputs, and outcomes (i.e., performance). The authors list primary reasons for using performance measures as follows:
- Refining operational procedures
- Supporting investment decisions
- Prioritizing projects
- Providing information for outreach efforts
- Responding to legislative inquiries
- Providing input for organizational changes

The study identifies the following measures for inputs, outputs, and outcomes:

Input performance measures:
- Number of scale facilities
- Number of road miles covered by enforcement
- Number of troopers and inspectors
- Number of heavy VMT
- Annual tons of overweight delivery
- Percentage of vehicles with permits
Output performance measures:
- Number of stops per hour worked
- Number of inspections per day
- Number of citations issued
- Number of inspections per million commercial vehicle operator miles driven
Outcome performance measures (measured for each link and summarized for the entire system)
- Percentage of vehicles over legal gross
- Percentage of vehicles over legal axle loads
- Dollars saved from reduced pavement damage
- Dollars saved from reduced bridge damage
- Percent of vehicles operating legally
- Number of citations issued versus number of vehicles inspected (calculated separately for roadside, mobile, and fixed scale inspections)

Examples of applications of performance measures include the following:

Virtual weigh stations (VWS) can be used to identify repeat offenders and target enforcement accordingly. Historical data could be compared to see if targeted violators are becoming more compliant due to targeted enforcement and the application of VWSs in this manner.
Bridge vulnerability indices could be developed that prioritize targeted enforcement schedules by identifying bridge structures with low sufficiency ratings and low compliance rates on associated roads.
Pavement vulnerability indices could be developed in a similar way to bridge vulnerability indices.
Hourly violation rate tables could be developed that determine which hours are most likely to have overweight trucks; this information would support targeted enforcement.

Fekpe et al. (2006, pp. 4-9) encourage the use of a performance-based compliance program and describe how this type of program may be designed and applied, particularly in the context of oversize/overweight (OS/OW) permitting. The authors indicate that a performance-based program should be robust and simple to administer, implement and monitor, and should use performance measures (or surrogate measures) that are easy to obtain using simple and quick roadside tests. They acknowledge that this may require an approach that differentiates trucks by configuration, commodity, and highway type in terms of enforcement and data collection. They propose issuing OS/OSW permits that restrict vehicles to designated routes defined by road class and that have been shown to be capable of supporting OS/OW loads contained in a permit. Permit fees should be related to infrastructure preservation but should be simple and practical to administer at a large national scale. The authors identify a permit fee option used in Saskatchewan that requires carriers to demonstrate the economic benefit of operating at higher weights and calculating their permit fee as 50 percent of the associated increased profit resulting from increased weight productivity. The authors recommend a simpler approach where fees are graduated based on axle loads.
The authors state that enforcement of performance-based programs requires the use of transponders and other electronic methods in addition to enforcement officers, regulations, special conditions, education and industry communication, fines and penalties, and adjudication. They envision enforcement personnel collecting transponder data and transferring it to a central clearinghouse where reports could be produced to determine if the vehicle complied with the permit conditions. Traditional enforcement programs require drivers to possess a hard copy of the permit and present it to enforcement officers for inspection, whereas performance-based systems would use intelligent transportation systems (ITS) to automatically determine the legality of a vehicle without requiring manual inspection of hard copy permits. The authors suggest that violations should result in the permit being revoked and the vehicle being suspended from operation.
URS (2013, pp. ii-vii) provides program recommendations as part of the development of a truck weight compliance business plan for Indiana. The plan recognizes the need for an outcome-driven decision-making course that: (1) addresses the needs of the freight transport industry; (2) helps minimize infrastructure damage; (3) addresses safety issues; (4) meets federal and state mandates regarding truck weight enforcement; and (5) supports the Moving Ahead for Progress in the 21st Century (MAP-21) transportation bill. In general, the aim of the plan is to reduce the infrastructure damage cost burden and shift the burden away from taxpayers through appropriate fine and permit structures.
DalPonte et al. (2015, pp. 3-5) use the size and weight enforcement program from Oregon to establish a performance management approach that may improve federal oversight of states’ size and weight programs. Specifically, they evaluate Oregon’s existing performance measures, which include:
- Truck-at-fault crashes;
- Inspections leading to a driver being placed out-of-service for a critical safety violation;
- Trucks weighed in motion and pre-cleared by Green Light (a program allowing registered vehicles with transponders to bypass static scales);
- Trucks weighed on static scales;
- Total trucks weighed (the sum of Green Light and static scale weighings); and
- Total weight-related enforcement actions (the sum of weight citations and warnings issued);
- Weight-mile tax audit recoveries. (Unlike nearly all other states, Oregon uses a weight mile tax rather than a fuel tax for trucks; the tax is levied based on the weight and number of axles and number of miles driven within the state.)
- The performance measures are considered as they relate to the following three enforcement program outcome relationships:
  - “As more truck drivers are placed out-of-service for critical safety violations, truck-at-fault accidents decline.”
  - “As more trucks are weighed and more scale crossings recorded, auditors recover more weight-mile tax dollars.”
  - “As more trucks are weighed, more weight citations are issued.”
- Their analysis recommends that Oregon retain their existing performance measures but supplement them with another measure to quantify the quality of services provided by the Department of Transportation staff to trucking firms. This could be in the form of the number of online inquires and calls answered by service representatives. Additionally, it is recommended that these measures be related to vehicle miles traveled to highlight enforcement efficiency.

2.2 Empirical Methods

The literature provides examples of the application of empirical methods to improve understanding of enforcement costs and the effectiveness of TSW enforcement activities. Specific methods evident in the literature include the use of scenario analyses (i.e., understanding compliance under varying enforcement conditions), pilot studies, and the use of weigh-in-motion (WIM) or vehicle inspection data to assess regulatory compliance.

Scenario analyses offer one way to understand the enforcement program performance and overcome data limitations and analytical uncertainties. Hanscom (1998, p. 13) integrates the proposed performance measures (identified above) into a software tool which uses them as the basis for statistical comparisons between two enforcement conditions (i.e., scenarios with and without enforcement activity). These comparisons can be made at a statewide/regional level, along a corridor, or at a specific location. Similarly, Strathman and Theisen (2002, pp. vii-viii) investigate the effectiveness of enforcing truck weights at a fixed weigh station on an interstate highway (Interstate 5) by collecting WIM data from three nearby sites: one site on the same interstate highway and two sites on potential by-pass routes. Data were collected prior to, during, and after an extended scale closure. Jones (2012, pp. 3-4) cites a study in Tasmania which applied a similar approach to investigate the effect of truck weight enforcement on the frequency of overweight violations detected.

Rooke et al. (2006, p. 21) evaluate the cost of enforcement activities for the European Union’s project REMOVE which seeks to provide a framework for WIM systems to reduce danger and damage caused by overweight vehicles. The authors determine enforcement costs for three enforcement scenarios: (1) manual selection; (2) WIM for pre-selection; and (3) WIM for direct enforcement. Finally, Australia’s National Transport Commission (2009, pp. ES-1, 2) estimates the costs and benefits over a five-year period of the National Heavy Vehicle Enforcement Strategy which was proposed in 2007 (National Transport Commission, 2007). Since considerable uncertainty exists when estimating benefits, three benefit scenarios (low, medium, high) were developed as part of the estimation process. Based on available data and experience, the low benefit scenario assumed a one percent reduction in heavy vehicle crashes, a one percent reduction in road damage, and a one percent improvement in enforcement efficiency. The medium and high benefit scenarios were calculated based on three and five percent improvements in these areas, respectively.

The use of pilot studies has also been used as an empirical method to analyze enforcement effectiveness. The TRB (2002) recommends this method for conducting various types of TSW policy analysis because of the magnitude of uncertainty associated with the impacts of changing TSW regulations. The FHWA (2012a, pp. 21-22) adopted this approach in the Vermont pilot program, which saw an increase in TSW limits on Vermont’s interstate highways for a one-year period, including allowance of a 6-axle tractor semitrailer limited to 99,000 lbs. gross vehicle weight. Among other objectives, the program enabled investigation of enforcement levels and overweight axles as a potential contributor to truck crashes.

An alternative empirical method for analyzing the effectiveness of truck weight enforcement relies on the use of WIM data to directly assess regulatory compliance, without specific regard for enforcement method. Regehr et al. (2010, pp. 8-9) assess regulatory compliance of three long truck configurations (Rocky Mountain doubles, Turnpike doubles, and triple trailer combinations) operating under special permit in the Canadian Prairie Region. The special permits contain vehicle, driver, operational, and network-related regulatory conditions. These vehicles are predominantly used to haul cubic (low density) freight. The authors use WIM data to assess compliance with (static) vehicle and axle weight regulations.

More recently, empirical research has also attempted to link overweight trucking and safety. Siekmann and Capps (2012, p. 19) provide interim findings to Federal Motor Carrier Safety Administration (FMCSA) concerning heavy and overweight vehicle defects, based in part on data obtained about overweight trucks from a nationwide data collection effort facilitated by the Commercial Vehicle Safety Alliance (CVSA).

2.3 Meta-Analysis and Survey-Based Methods

The literature contains a number of studies that address enforcement costs and effectiveness through a compilation and analysis of survey and/or literature findings. In certain cases, this approach is adopted because the primary objective of these studies was to conduct a meta-analysis rather than primary research. Principal examples of this are the recent synthesis of literature concerning TSW enforcement practices and performance produced by Carson (2011), and a report by Australia’s National Transport Commission (2011a) which synthesizes international best practices for achieving regulatory compliance.

In other cases, the analysis of survey and/or literature findings are applied to assess enforcement effectiveness because of the lack of empirical data on the subject. Straus and Semmens (2006, pp. 24-25, 55-58) estimate the cost of overweight vehicle travel on Arizona highways. To support this analytical work, the authors provide results from a survey of 25 states concerning their experiences with truck weight enforcement and overweight trucking. Similarly, Ramseyer et al. (2008, pp. 31-53) conduct a survey of all 48 contiguous states concerning enforcement and compliance, with 38 states providing responses (although not every question was answered by each respondent). The survey results provide useful information about truck weights and overloading. Cambridge Systematics (2009a) interviews nine states to determine best practices in the deployment of roadside enforcement technologies. Finally, Honefanger et al. (2007) summarize and evaluate procedures and technologies for enforcing TSW laws in Europe (Belgium, France, Germany, the Netherlands, Slovenia, and Switzerland), based on an international scanning tour which involved interviews with TSW enforcement officials from each of these countries.

CHAPTER 3 – Assessment of Future Research and Data Needs

This chapter summarizes recommendations for improving the understanding of the costs and effectiveness of TSW enforcement programs, citing international, national, and state-specific studies. The literature contains several studies that make recommendations concerning how TSW enforcement programs may achieve their compliance goals. Many of these recommendations refer to a general lack of reliable data on truck weights and the effectiveness of truck weight enforcement programs; therefore, specific data needs and potential data sources are identified. Finally, the literature discusses the ongoing debate about the range of strategies considered to deliver TSW enforcement programs—from deterrence-based enforcement methods to approaches aimed at incentivizing compliance.

TRB (1990, pp. 135-143) recommends the following congressional actions to improve enforcement of truck weight laws: (1) direct federal funding of state enforcement; (2) imposition of federal penalties for violations of federal weight limits on interstate highways, or alternatively, mandating of minimum state penalties; (3) federal provision for assessing penalties against parties for placing overweight shipments into commerce; (4) federal support for state measures to place overweight trucks out of service until they are offloaded; (5) development of educational programs for judges and prosecutors regarding the overweight problem; and (6) creation of a federally managed program for systematic collection of data on violators that would identify the responsible carrier or other operator so repeat offenders could be targeted.

A second TRB report on TSW regulation (2002, pp. 170, 175, 183) echoes many of the initial recommendations made in 1990. This report indicates that “few evaluations” have been conducted on the impact of enforcement strategies on the frequency and magnitude of weight violations. Moreover, the report suggests that effective adoption of enforcement technologies has the potential to induce “substantial cost reductions” for enforcement programs, regardless of whether changes to TSW limits occur. This lack of evidence stems from an absence of available data and the inability to implement statistically valid truck weight sampling plans. Specially-permitted oversize and overweight vehicles require particular attention within enforcement programs. Recommendations to develop information systems to support compliance assessment, enforcement effectiveness and targeting, the benefits of effective enforcement, and program evaluation are evident in the literature since at least the early-1990s, namely from the TRB Truck Weight Limits Study (1990) and a report by the Office of Inspector General (1991).

TRB (2002, p. 176) summarizes the proposed enforcement reforms made by the Office of Inspector General (OIG) Report (1991). This report recommends the following measures: (1) develop a program to produce the data needed to quantify the extent of overweight traffic; (2) require that states formulate annual enforcement plans and demonstrate the effect of enforcement on violations; (3) develop standards and technological improvements for WIM systems; (4) restrict state use of divisible-load permits and multiple-trip non-divisible load permits on the interstate system; (5) evaluate fine structures; and (6) promote non-traditional enforcement techniques (such as the inspection of shipping and receiving logs for illegal loads).

Recommendations for more targeted enforcement programs have also been evident internationally (notably in Australia and Europe). Allen (2002, p. 177) provides two principles governing targeted TSW enforcement. First, the entire population of heavy vehicles should be monitored to control the system and provide the range of compliance rates within the industry. This enables a regulator to identify current and future outliers within a dynamic industry. Second, targeted enforcement should identify and capture high-risk offenders that fall outside established regulatory limits. This principle relies on appropriate processes to remove offenders from the industry or bring their behavior back into accepted norms. Moreover, Quinlan (2002, p. 242) indicates that a coordinated and targeted compliance approach in the road transport industry is needed to overcome fragmented regulatory approaches. Fragmented approaches are “unfair, inconsistent, confusing […] and offer too many avenues for calculated evasion.” Rooke et al. (2006, p. 51) reveal that the current practice of applying liability to the driver and/or operator is not conducive to achieving compliance across the haulage industry. They indicate that the road transport industry is “generally in favor” of taking the problem-solving approach to enforcement which involves targeting carriers with a history of non-compliance.

URS (2005, pp. 33-52) identifies the key issues to be addressed to improve enforcement effectiveness in a statewide commercial vehicle weight compliance strategic plan developed for Minnesota. These issues include:

Trucks by-passing fixed weigh stations;
Declining enforcement resources and/or fixed resources with increasing truck volumes;
The need for enforcement programs to be performance-based and to use performance measures to guide decision-makers;
Inability to measure compliance;
Apparent ineffectiveness of fixed weigh scales for weight enforcement shortly after the scale opens;
Potential for portable scales to be used on lower volume highways;
Potential for using WIM devices as weight enforcement tools rather than exclusively for planning purposes;
Importance of WIM maintenance and accuracy and the required resources to maintain adequately operating WIMs;
The need to enhance traditional enforcement approaches to allow field inspectors to determine if an overweight vehicle has a permit prior to pulling the vehicle over; and
The need to establish and refine practical performance measures for weight enforcement that are effective and affordable.

A more recent study by URS (2013, pp. ii-vii) provides program recommendations as part of the development of a truck weight compliance business plan for Indiana. The report recommends:

Maintaining existing fixed scales and restoring functionality at one scale that had been decommissioned;
Expanding the functionality of the existing central database server;
Upgrading several existing WIM sites to virtual WIM sites;
Strengthening coordination between agencies involved in truck weight compliance within the state;
Analyzing the impact of a recent regulatory change in Indiana which permits divisible loads up to 120,000 pounds;
Changing the current permit fee structure to one which reflects the damage caused by varying axle loads; and
Building fixed weigh scales in regions in the state where this infrastructure is currently lacking.

Specific data needs and sources have been identified in several studies. In a review of federal TSW enforcement programs, the USDOT (2000, pp. VII-4 to VII-6) notes a general improvement in the level of enforcement activity resulting from requirements for states to develop and certify state enforcement plans (SEPs) and the adoption of technologies such as WIMs for pre-screening. These state-submitted data have been used to track enforcement costs and effectiveness, principally in terms of the number of trucks weighed, the number of citations issued, violation rates, and requirements for vehicle offloading and load shifting. Quantifying the degree of non-compliance “continues to be difficult.” URS (2005, p. 58) identifies examples of existing data sources that could support performance-based enforcement programs. These sources include: truck traffic data (e.g., vehicle classification sites, traffic volume counters, and WIM scales); relevant evidence data; pavement and bridge sufficiency ratings; and safety data. Fekpe et al. (2006, p. 4) recognize the need to collect data that differentiates trucks by configuration, commodity, and highway type. Finally, a more recent report by the OECD (2011, p. 298) also recognizes the value of applying WIM to support truck weight enforcement programs. This report states that WIM technologies have the potential to deliver more detailed, continuous data about weight compliance, specifically by utilizing axle spacing measurements to isolate the compliance record of higher capacity configurations.

The recommendations and research and data needs identified in the foregoing literature appear to reflect an ongoing debate about how to best improve the effectiveness of truck weight enforcement programs. Thomas (2002, pp. 125, 129) asserts that the debate about what constitutes effective enforcement will remain unresolved. In essence, one side of this debate encompasses the view that more enforcers mean more enforcement, and more enforcement is more effective. The alternative view favors enforcement effectiveness gained through court-delivered sanctions, which should direct behaviors towards compliance. The author suggests that “the most important key to effective enforcement is the engaging of all industry parties to play a more proactive role in managing all facets of their business operations to achieve compliance with their legislative obligations.”

Australia’s National Transport Commission (2011a, pp. iii-iv) discusses this ‘enforcement versus compliance’ debate more extensively in its synthesis of international best practices for achieving regulatory compliance. Borrowing from compliance and regulatory practices in fields other than trucking, the report concludes that the dualistic enforcement (deterrence) versus compliance thinking has evolved into a wider range of options, with no internationally-accepted best practice. More specifically, the report identifies seven regulatory strategies, including:

Rules and deterrence, which emphasizes an “adversarial style of enforcement” and penalties for rule-breakers;
Advice and persuasion, which emphasizes co-operation rather than confrontation to prevent harm and avoid sanctioning;
Responsive regulation, which features a combination of the two foregoing strategies;
Smart regulation, which expands on responsive regulation by emphasizing the role of the market and society in acting as a regulator;
Metaregulation, which requires regulated entities to submit compliance plans for approval, with the regulator acting as a risk manager;
Risk-based regulation, which emphasizes the need to adjust the regulator’s response to non-compliance based on the risk that the non-compliant event poses to the regulator’s objectives; and
Criteria-based strategy, which enables a wide range of compliance and enforcement responses, chosen based on consideration of pertinent criteria.

The report also identifies five compliance assurance tools, including:

Tools used prior to a regulated activity (e.g., licenses, permits);
Tools designed to encourage or reward compliance (e.g., education, advice);
Tools that remind an entity of regulatory responsibility (e.g., prohibition notices);
Tools involving penalties or sanctions; and
Tools that use rewards and positive motivation to encourage behavioral change.

Finally, the report identifies an emerging approach known as informational regulation, which provides information on the operations of regulated entities to affected stakeholders, who then exert pressure on the regulated entity to improve compliance.

The National Transport Commission’s report concludes that there is a need to improve the scope of tools used to achieve compliance, by drawing strategically from those tools at the bottom and top of the ‘enforcement pyramid’ (which emphasize compliance and deterrence, respectively). Specifically, the need for more reliance on rewards-based tools and informational regulation is identified. When selecting an appropriate mix of tools, however, regulators should be aware that some combinations of tools may be counter-productive.

The OECD (2011, pp. 281-282) appears to concur with the National Transport Commission’s policy and programmatic recommendations concerning TSW enforcement and compliance. The OECD quotes an Australian report by McIntyre and Moore (2002, p. 1), which lists the following issues with the traditional truck weight enforcement approaches:

“Fines, no matter how high, will not have a sufficient deterrent effect when the chance of detection is slight and the potential profits from offending are high.
Targeting only the truck driver and operator has no deterrent impact on the many ‘off-road’ parties who have a significant influence on on-road compliance and leads to a perception amongst drivers and operators that they are being treated unfairly.
In an industry characterized by high levels of competition resulting from low barriers to entry and a large number of small operators, the survival of operators who attempt to achieve levels of compliance higher than industry standards will be threatened.
A culture founded on confrontation between the regulator and the regulated is not conducive to promoting voluntary compliance.”

The OECD report also suggests (p. 295) that the level of compliance achieved depends on:

“The degree to which the target group knows of and comprehends the rules”;
“The degree to which the target group is willing to comply—either because of economic incentives, positive attitudes arising from a sense of good citizenship, acceptance of the policy goals, or pressure from enforcement activities”; and
“The degree to which the target group is able to comply with the rule.”

The report identifies consistent, targeted enforcement as one of a set of “compliance-enhancing tools,” which includes incentives-based strategies, training of enforcement officers, industry education and communication, monitoring compliance levels and effectiveness, and conducting ongoing research.

Australia, in particular, has pursued alternative approaches to achieving regulatory compliance as recommended by the National Transport Commission (2011a) and OECD (2011) reports. Appendix A contains further details on Australia’s experience.

CHAPTER 4 – Synthesis of Quantitative Results

This chapter provides a synthesis of quantitative results concerning the costs and effectiveness of TSW enforcement programs. It contains four sections: (1) costs and benefits of TSW enforcement programs; (2) the effectiveness of TSW enforcement programs; (3) the effectiveness of on-road enforcement methods; and (4) regulatory changes and the effectiveness of TSW enforcement. While quantitative results are of primary interest, qualitative descriptions of operations and effectiveness of these methods are also included.

4.1 Costs and Benefits of TSW Enforcement Programs

There is relatively little directly relevant information in the literature about the programmatic costs of conducting TSW enforcement. The previous Comprehensive Truck Size and Weight Study conducted by the USDOT provides the most detailed assessment of TSW enforcement program costs (and related activities) available. Using state-reported data, the USDOT (2000, pp. VII-6 to VII-7) reports nationwide statistics as follows:

Total nationwide expenditures on TSW enforcement reported by states in 1995 was approximately $281 million.
Total nationwide weighings reported by states ranged from approximately 105 million to approximately 170 million between 1985 and 1995.
Total nationwide non-WIM weighings (i.e., fixed platform, portable, semi-portable) reported by states ranged from approximately 97 million to approximately 124 million between 1985 and 1995.
Total nationwide load-shifting and offloading vehicles reported by states ranged from approximately 478,000 to approximately 579,000 between 1985 and 1995.
The average nationwide cost per non-WIM weighing was approximately $2.50 in 1995.

Other studies approach the assessment of enforcement costs and benefits more generally, often reporting the cost imposed by overloaded vehicle travel or the benefits (and sometimes costs) resulting from the elimination of overloaded vehicles. Citing TRB (1990), TRB (2002, p. 174) indicates that if no change in the quantity of truck freight occurred, the elimination of illegal overloads could reduce pavement costs by $160 million to $670 million per year in the United States. Further, “rigorous enforcement” would cause a 0.5 to 2.5 percent increase in annual vehicle miles traveled by large trucks, corresponding to an annual cost to shippers of $500 million to $2.5 billion. These figures may encourage shippers to “pay the added pavement costs generated by their overloaded trucks instead of reducing their loads.”

Stephens et al. (2003, pp. 143-148) use WIM data to determine the pavement damage caused by overweight vehicles each month and identify the vehicle configurations and travel characteristics (e.g., time, direction) contributing the most to pavement damage. This information was used to deploy officers to the top five sites in terms of damage caused by overweight trucks. In the subsequent year of targeted enforcement using this information, pavement damage from overweight vehicles decreased by 4.8 million ESAL-miles (approximately $500,000 in savings) and the number of overweight vehicles at the WIM locations decreased by 20 percent. Due to the short timeframe of the program (i.e., one year to identify the top five locations and one year to target enforcement) the authors caution the extrapolation of these results to long-term horizons and acknowledge that there are year-to-year changes in overweight vehicle operations irrespective of enforcement activity. The authors find that there were increases in overweight vehicles at other enforcement sites that had lower enforcement activity due to shifting resources based on WIM information; however, these were generally low-volume sites.

Straus and Semmens (2006, pp. 24-25, 55-58) estimate the cost of overweight vehicle travel on Arizona highways. As a basis for the range of estimates presented, the authors use cost figures attributed to all commercial vehicles from Arizona’s highway cost allocation model and the proportion of federal estimates of nationwide pavement maintenance costs allocated to Arizona. These figures indicate that pavement damage costs attributable to commercial vehicles (including overweight trucks) in Arizona range between $210 million and $420 million per year. From this starting point, the authors factor in costs specifically attributed to overweight trucks (based on an estimate that 15 percent of trucks operate overweight), the disproportionate damage caused by heavier axles, and revenues generated by heavy vehicle travel. The authors conclude that “overweight vehicles impose somewhere between $12 million and $53 million per year in uncompensated damages to Arizona highways.” Arizona spends nearly $6 million on mobile enforcement activities, which are in part directed at deterring overweight trucking. Thus, if doubling the budget for mobile enforcement was “50 percent effective toward the objective of eliminating illegally overweight vehicles,” annual pavement damage savings would range from $6 million to $27 million. These figures translate into a range of benefit-cost ratios between one and four or five.

Australia’s National Transport Commission (2009, pp. ES-1, 2) estimates the costs and benefits over a five-year period of the National Heavy Vehicle Enforcement Strategy which was proposed in 2007 (National Transport Commission, 2007). This strategy aimed to promote consistent, effective and efficient enforcement in heavy vehicle transport law in Australia. In particular, the strategy focused on increased use of intelligence-driven enforcement and coordinating practices between Australian states as they implement reforms such as the chain of responsibility principle.

The National Transport Commission indicates that the main costs associated with implementation of the strategy relate to the collection and analysis of data and the establishment of national coordination practices. In total, costs to the enforcement agency (in 2008 Australian dollars) summed to $2.6 million in year one and rose to $3.1 million per year thereafter. Benefits gained by more targeted enforcement included heavy vehicle crash reduction, reduced road damage from overloading, and improved enforcement cost efficiencies. Since considerable uncertainty exists when estimating benefits, three benefit scenarios (low, medium, high) were developed as part of the estimation process. Based on available data and experience, the low benefit scenario assumed a one percent reduction in heavy vehicle crashes, a one percent reduction in road damage, and a one percent improvement in enforcement efficiency. The medium and high benefit scenarios were calculated based on three and five percent improvements in these areas, respectively. Under these scenarios, in 2008 Australian dollars, the following annual benefits were calculated: (1) between $13 million and $65 million for reduced heavy vehicle crash costs; (2) between $0.6 million and $2.8 million for reduced road wear; and (3) between $1.2 million and $6 million for improved enforcement efficiency. In terms of net present value over the five-year period (using a four percent discount rate); the strategy would see a net benefit ranging from $38 million to $246 million, corresponding to a benefit-cost ratio of between 4 to 1 and 20 to 1. Even a 50 percent increase in costs would see net benefits and benefit-cost ratios between 2.6 to 1 and 13 to 1.

Rooke et al. (2006, pp. 21-25) evaluate the cost of enforcement activities for the European Union’s project REMOVE which seeks to provide a framework for WIM systems to reduce danger and damage caused by overweight vehicles. The authors determine enforcement costs (shown in Table 27) for three enforcement scenarios: (1) manual selection; (2) WIM for pre-selection; and (3) WIM for direct enforcement. These figures assume that the number of overloaded vehicles remains the same regardless of the enforcement scenario and that WIMs used for direct enforcement require a higher level of accuracy than those used for pre-selection.

Table 27: Costs to Enforcement Agency by Enforcement Scenario
Scenario	Enforcement cost per year	Enforcement cost per year per officer	Enforcement cost per year per overloaded vehicle
Manual selection	€ 160,000	€ 53,333	€ 145
WIM for pre-selection	€ 422,500	€ 70,417	€ 75
WIM for direct enforcement	€ 322,150		€ 3

Rooke et al. also estimate the cost of damage to infrastructure by overloaded vehicles in the European Union. Due to limited research the term infrastructure refers only to roadways. The estimated cost of damage incurred from overloaded vehicles is composed of the cost of road maintenance and the corresponding cost of traffic delays caused by road maintenance. Using the Netherlands data to estimate damage costs and assuming the same percentages hold for the other 14 EU countries, the authors reason that the EU spends from €239 million to €557 million on repairing road damage caused by overloaded vehicles. Considering only the national road networks the cost ranges from €153 million to €227 million. For comparison, the road maintenance budget of the 15 EU countries combined is €10,500 million. The authors conclude that the “possible level of damage to the infrastructure caused by overloaded vehicles is significant.” As well, the potential savings from using correctly loaded goods vehicles is significant. They recommend member states set targets to “reduce maintenance budgets by effective compliance strategies for overloaded vehicles.”

URS (2013, p. ii) develops a business plan for Indiana’s truck weight compliance program. The report cites proven performance of a pilot virtual WIM site in the state. Based on data collected at this site, the report estimates that a “conservative minimum estimate of $850,000 per year in pavement preservation can be saved across the state network with a comprehensive compliance program”. This estimate could range as high as $3 million per year (or even higher). The report also estimates that the cost of a virtual WIM installation would be recovered by the enforcement agency through pavement damage reduction in three to six years.

4.2 Effectiveness of TSW Enforcement Programs

The costs and benefits of TSW enforcement programs provide one indication of program effectiveness; however, the literature also assesses effectiveness by attempting to quantify the magnitude of overweight trucking.

In one of the most comprehensive reviews of issues concerning truck weight limits, the TRB (1990, p. 141) finds that “reliable estimates of the magnitude and frequency of illegal overloads are not available.” Available WIM data collected in six states between 1984 and 1986 reveals that “about 10 to 20 percent of all combinations are operating illegally overweight without a permit.” A survey of truck weight enforcement personnel corroborates this finding by suggesting that “more than 10 percent but less than 25 percent of trucks are overloaded.”

A more recent TRB report (2002, pp. 171-172) on TSW regulation draws similar conclusions, stating that estimates of operating weights of trucks are “fragmentary and inconsistent.” According to state officials, overloading problems appear to be concentrated in certain industry segments which haul bulk, high density (i.e., weigh-out) commodities. The authors cite estimates of actual non-compliance made by four independent studies.

Grenzeback et al. (1988) “estimate that 15 percent of large trucks would exceed axle weight or GVW limits on a segment of interstate highway where enforcement was not taking place.” This study also suggests that a “minimum” violation rate of six percent exists at fixed scales.
A study by the FHWA (1993) indicates that “only 0.6 percent of trucks exceed gross vehicle weight limits at weigh stations.” This number is affected by overweight trucks that “routinely avoid the stations.”
Hajek and Selsneva (2000) estimate that 12 percent of tandem axles exceeded the federal (U.S.) maximum of 34,000 lbs., according to data collected at several hundred WIM sites.
Unpublished USDOT estimates attribute “10 percent of all miles of travel by trucks with three or more axles to vehicles weighing more than 80,000 lbs.” This includes both legal and illegal overload operations. No information is provided in the report about when these data were collected.

The USDOT (2000, pp. VII-6 to VII-7) reports nationwide citation rates (weight citations per non-WIM weighing) ranging from 0.006 and 0.007 in the period from 1985 and 1995, based on state-reported truck weight enforcement activity data. In each of the years reported, the weighings occurring at fixed weigh scales exceeded 97 percent of all non-WIM weighings. A citation rate provides an indication of the magnitude of the overweight trucking problem, but may not be representative of all trucking activity.

More recent studies quantify the extent of overweight trucking by using WIM data to isolate specific truck configurations and by analyzing data obtained from truck safety inspections. Regehr et al. (2010, pp. 8-9) assess regulatory compliance of three long truck configurations (Rocky Mountain doubles, Turnpike doubles, and triple trailer combinations) operating under special permit in the Canadian Prairie Region. The special permits contain vehicle, driver, operational, and network-related regulatory conditions. These vehicles are predominantly used to haul cubic (low density) freight. The authors use WIM data to assess compliance with (static) vehicle and axle weight regulations. The weight analysis, which was based on one year of (dynamic) weight data from a single WIM located on the Trans-Canada Highway, reveals that 99 percent (22,823 of 23,092) of Rocky Mountain doubles and Turnpike doubles comply with their static weight limit. Similarly, 99 percent of the dynamically measured single, tandem, and tridem axle weights were compliant with static weight limits. Steering axles were found to be compliant between 92 and 95 percent of the time. The analysis does not relate compliance to particular on-road enforcement methods.

Siekmann and Capps (2012, p. 19) provide interim findings to FMCSA concerning heavy and overweight vehicle defects. Based on data obtained about overweight trucks from a nationwide data collection effort facilitated by the CVSA and an additional, smaller but more detailed dataset, the authors conclude the following:

Of the 1,873 Level 1 inspections performed on overweight vehicles in 18 states over a six-month period, a vehicle out-of-service (OOS) violation was found on 44.79 percent of the vehicles. This rate is higher than the national OOS rate of 27.23 percent.
Brake-related defects were the main reason for a vehicle being placed OOS, “with approximately 30 percent of all vehicles having an OOS brake violation”. Properly working brakes are “important in order to reduce the potential for crashes”.
Axle weight violations were more common than GVW violations, with about two-thirds of vehicles cited with a weight violation being overweight on axles. On average, axle weight violations exceeded legal limits by 2,000 pounds.

Siekmann and Capps conclude that “it may not be safe to assume that a vehicle found to be overweight as part of this data collection effort is overweight on every load they haul, but it can be inferred that vehicles that tend to be overweight occasionally are lacking proper vehicle maintenance”.

Indications of the magnitude of the overweight trucking problem have also been estimated through state-based surveys and data collection efforts. Straus and Semmens (2006, pp. 55-58) provide results from a survey of 25 states concerning their experiences with truck weight enforcement and overweight trucking. Responses indicate a wide-range of estimates (between 0.5 and 30 percent) as to the proportion of vehicle travel that is overweight in the surveyed states. Ramseyer et al. (2008, pp. 31, 49-53) conducted a survey of all 48 contiguous states concerning enforcement and compliance with 38 states providing responses (although not every question was answered by each respondent). The survey finds the following:

Five of 12 responding states report that less than five percent of trucks weighed at weigh stations are overloaded; three of 12 responding states report overloaded rates at weigh stations between five and ten percent; two of 12 responding states report overloaded rates at weigh stations between ten and 15 percent; and two of 12 responding states report overloaded rates at weigh stations between 20 and 25 percent.
15 of 35 respondents indicated that weight compliance has increased due to implementing the Commercial Vehicle Information Exchange Window (CVIEW) or Commercial Vehicle Information Systems and Networks (CVISN); four indicated that compliance has not improved and 16 were undecided.
23 of 28 respondents indicated that intrastate trucks are overloaded more frequently than interstate trucks; two indicated that overweight trucks were equally distributed between intrastate and interstate trucks; and three indicated that interstate trucks are more frequently overloaded than intrastate.
14 of 26 respondents indicated that trucks with bulk material were most frequently overloaded; four indicated trucks with construction or commercial material were most frequently overloaded; and eight indicated that all types of trucks were equally likely to be overweight.

When considered together, despite some advances, the literature findings suggest that the lack of a comprehensive understanding of the magnitude of the overweight trucking problem in the United States—as identified by TRB some 30 years ago—remains today. Carson (2011, p. 38), concludes similarly in a recent compilation of significant TSW research, stating that there is a lack of reliable estimates on the extent of illegal TSW activity available in published research. This, combined with disparate enforcement practices across the United States, “challenges the ability to accurately assess the direct relationship between enforcement activities and truck size and weight compliance.” The literature that does exist (which is principally published prior to 2000) generally concludes that higher enforcement levels result in improved compliance. At fixed weigh scales on interstate highways, Carson reports a violation rate when enforcement is present of one percent, but a violation rate without enforcement of 15 percent. By-pass routes have violation rates of approximately 30 percent.

4.3 Effectiveness of On-Road Enforcement Methods

While uncertainty about the magnitude of overweight trucking remains, several studies have attempted to clarify the effectiveness of specific on-road enforcement methods. The use of fixed weigh scales and mobile enforcement patrols are the two most common methods of enforcing truck weights in the United States. More recently, states have complemented these methods with the application of numerous TSW enforcement technologies, including WIM devices and VWS (U.S. DOT 2000; TRB 2002; Cambridge Systematics 2006; Ramseyer et al. 2008; Cambridge Systematics 2009a; Cambridge Systematics 2009b; Carson 2011; OECD 2011). Carson (2011, p. 38) acknowledges the variety of TSW enforcement methods deployed in the United States and partially attributes the lack of a comprehensive understanding of the effectiveness of on-road enforcement methods to this disparity. Carson concludes that enforcement programs that combine fixed and mobile activities are “most effective in ensuring truck size and weight compliance,” though these approaches have more recently been supplemented by greater implementation of technologies that broaden the temporal and geographic coverage of enforcement. The effectiveness of on-road enforcement efforts may be impeded by realities of the judicial system, where misdirected or ineffective penalties may exist and misunderstanding about the impacts of truck overloading leads to low prioritization in the court system.

This section chronologically presents findings about the effectiveness of on-road enforcement methods (i.e., fixed, mobile, WIM and VWS), in the context of their deployment within a TSW enforcement program. It also discusses how aspects of the judicial system (i.e., the level of sanctions and the use of relevant evidence) influences enforcement effectiveness.

4.3.1 Fixed Weigh Scales

Taylor et al. (2000, pp. 237-238) suggest that low violation rates at weigh scales on primary highways is indicative of an effective enforcement program that deters overweight vehicles rather than an indication that enforcement is not required. The authors further suggest that accelerated infrastructure damage on secondary roads with less enforcement is an indication that increased enforcement is necessary. They reference studies performed by seven state agencies to conclude that overweight violation rates are around one percent for continuously operated (i.e., high enforcement level) weigh scales on U.S. interstates and between 12 and 34 percent for low enforcement level weigh scales (there is no definition for “low level”).
Taylor et al. (p. 239) also identify studies in Virginia and Idaho which found that up to 14 percent of truck traffic will use alternative routes to avoid weigh scales and that operators will travel up to 160 miles to avoid a weigh scale. Virginia has found that trucks will purposely group together to exceed the ramp capacity of a weigh scale, known as weigh scale running or plugging. Overweight trucks travel at the rear of these groups and bypass the scale when it has been temporarily closed. Virginia has found that more than 38 percent of trucks that were running by the scale were found to be overweight.

Finally, Taylor et al. (p. 241) reference a model developed by researchers in Idaho which predicts that a continuously operated weigh scale with an area coverage of 160 miles would prevent approximately $46 million in pavement damage over the life of the pavement. Further, the authors indicate that a combination of fixed and mobile enforcement provides the best overall weight enforcement program.
Strathman and Theisen (2002, pp. vii-viii) investigate the effectiveness of enforcing truck weights at a fixed weigh scale on Interstate 5 by collecting WIM data from three nearby sites: one site on I-5 and two sites on potential by-pass routes. Data were collected prior to, during, and after an extended scale closure. The study finds that trucks did not appear to avoid the scale; further, trucks did not divert to I-5 during the scale closure. The authors indicate that GVW on I-5 increased by 0.4 percent when the scale closed and decreased by 1.2 percent upon re-opening (these were statistically significant changes). The number of overweight vehicles (at a 95 percent confidence level) before closure was 2.27 percent, during closure was 3.67 percent (an increase of 61 percent), and after re-opening was 3.19 percent (a decrease of 13 percent). The authors found that five-axle combination trucks (including tractor semi-trailers and truck-trailer configurations) were “somewhat” more likely to exceed weight limits compared to other vehicle classes during this case study. Changes in weight for participants in the Green Light program (a transponder-based weigh station preclearance program) were minimal, suggesting that these operators were self-compliant or unwilling to risk losing their status and associated benefits.
Strathman and Theisen also suggest that: (1) relatively aggressive enforcement in Oregon reduces the impact of increases in truck weight due to a single scale being shut down; (2) weight enforcement at a single site on I-5 which is a major interstate and international corridor may have little impact on interstate truck weights; and (3) operators participating in truck programs that offer benefits to compliant trucks are less likely to operate heavier trucks.
Han et al. (2012, p. 268) test adaptive WIM threshold algorithms that dynamically alter the weight threshold of advanced WIM sorting systems for inspection stations as they near capacity. The results show that fewer commercial vehicles enter the inspection station as it fills up and those that do are selected by a heavier weight threshold. Adaptive WIM threshold algorithms increase inspection station throughput without large capital investment, decrease the time inspection stations are closed, and remove a greater proportion of commercial vehicles with weight violations.

4.3.2 Mobile Enforcement

Allen (2002, p. 180) states that visible mobile enforcement, when supported by portable computing equipment to enable real-time data input and extraction, “can deliver a significant level of behavioral change at a high benefit/cost ratio.”
The USDOT (2000, p. VII-7) indicates that trucks with more axles require more time to weigh. The report indicates that in Michigan, as an example, it takes two hours to weigh an 11-axle combination truck using portable scales.
Straus and Semmens (2006, pp. 31-45, 55-58) provide results from a survey of 25 states concerning their experiences with truck weight enforcement and overweight trucking. The survey revealed the following insights:
- Mobile enforcement is useful for detecting and deterring overweight vehicle travel. Responses indicate a wide range of commitment to mobile enforcement programs in terms of budgets, person-hours assigned to this duty, and the number of vehicles weighed. On average, the budget for a state mobile enforcement unit was $3.7 million annually.
- Of the vehicles weighed using mobile enforcement the percentage of vehicles exceeding legal limits ranged from less than one percent to nearly 100 percent in the surveyed states. This range likely reflects the presence of targeting strategies. Of the overweight vehicles (where data are available), the average number of pounds overweight (on the whole vehicle) ranged between 2,000 and 10,000 lbs.
- Evidence that trucks knowingly violate truck weight laws supports the notion of increasing resources on state roads during “after hours” times.
- Of the various vehicle classes, class 9 vehicles (i.e., five-axle tractor semitrailers) have the highest rate of in-state overweight violations.
Honefanger et al. (2007, p. 2) evaluate procedures used for commercial vehicle size and weight enforcement in six European countries as part of an FHWA report. They find that there is a greater use of mobile enforcement activities than fixed roadside weigh scale facilities. The result is that fewer trucks are processed and inspection areas are physically constrained but there is more flexibility to respond to industry and more effective enforcement action.

4.3.3 WIM and VWS

USDOT (2000, pp. VII-13 and VII-14) suggests that the use of WIM as a pre-screening device at fixed weigh scales “improve[s] the efficiency and effectiveness of operations.” The report also indicates that WIM devices require frequent maintenance and may not provide continuous operation. The report identifies the integrated use of WIM and photo imaging as a plausible option for issuing weight citations.
TRB (2002, pp. 179-182) describes the use of automatic clearance systems (such as PrePass), which screen trucks on the road and allow non-violators to by-pass enforcement stops. These systems improve enforcement efficiency by enabling officers to target trucks more likely to be in violation, thereby reducing the cost of enforcement for the public sector and the enforcement-related costs incurred by carriers. The study discusses extended applications of automatic vehicle identification (AVI) technology, specifically in terms of permit enforcement, identification of repeat offenders, and automated on-board enforcement techniques. The study also identifies the need for databases and information systems to improve enforcement efficiency. Data needs include inspection histories and violations of size and weight, safety, and other truck regulations. “Data must be accessible in the field, comprehensive, and current.”
Gu et al. (2004, p. 7) evaluate the use of WIM technology to reduce delay and improve enforcement at weigh scales through the use of micro-simulation software. The report evaluates weigh station design and operation by simulating different design strategies (one static scale, two static scales, ramp WIM scale, and mainline WIM scale), the impact of weight threshold used, WIM accuracy, and the percentage of trucks in the traffic stream equipped with transponders. The following conclusions are made: (1) the use of WIM technology improves the efficiency of weigh scale operation; (2) at least 30 percent of trucks should be equipped with a transponder (used to inform drivers if they need to enter the weigh scale) for mainline WIM operation to be effective; (3) due to the current level of transponder usage in the fleet (less than 30 percent), WIM scales are more effective on weigh scale ramps than on mainlines; (4) accuracy of WIM scales is “an important issue;” and (5) threshold levels are important to achieve a balance between weigh scale efficiency and effective enforcement.
Santero et al. (2005, p. 15) analyzes the effects of overweight trucks on California highways and the potential benefit of implementing VWS. The author finds that 5.74 percent of pavement damage on the California highway network is directly associated with overweight trucks that represent fewer than 2.67 percent of the axles measured. Damage is calculated using ESALs that increase exponentially with vehicle weight. This results in overweight trucks being disproportionately large contributors to pavement damage. They conclude that if VWS were installed at the ten existing WIM sites which could provide the greatest benefit, the average pavement life saved across those sites would be 10.71 percent. The report assumes that “when installed, a VWS is 100 percent effective in deterring overweight vehicles” (p. 9) and that the WIM database is representative of the entire state network.
URS (2005, pp. 2-3, 48-51) develop a statewide commercial vehicle compliance strategic plan for Minnesota. The report indicates that achieving truck weight compliance is complex and requires more than enforcement. The authors recommend establishing a network of virtual WIM stations to measure compliance and use Civil Weight Enforcement to help target enforcement efforts. Minnesota uses Civil Weight Enforcement (part of relevant evidence enforcement) to target repeat weight violators. This allows enforcement officers to use virtual WIM stations to identify habitual offenders and use this information to visit their premises and issue a civil citation (up to $10,000 fine).
The study indicates that weight violators are rarely caught at fixed weigh scales and recommends installing VWS as a more effective approach. The study provides considerations for implementing VWS as follows:
- Roads with volumes greater than 500 vehicles per day
- Mainline roads in front of fixed weigh scales
- Primary, known by-pass routes for fixed weigh stations
- Ramp sorters at fixed weigh stations
- Trunk highways with substantial truck volumes
- Highways with high bulk commodity movements (e.g., agriculture)
- Highways with one or more vulnerable bridge structures
- Newly rehabilitated roadways with significant truck volumes
The study estimates and compares enforcement costs for fixed weigh scales and virtual WIM enforcement stations. They find that approximately 100 WIM sites could be built for the cost of one fixed scale site (this assumes $15 million for fixed site construction and $150,000 for a WIM site) and the annual operating costs for 100 WIM sites is about one-quarter of the annual cost of one fixed site.
Cambridge Systematics (2006, p. D-11) outlines two specific benefits of VWS. First, these stations enable officers to target enforcement efforts on overweight vehicles, which reduces the amount of time used for weight enforcement at fixed weigh scales. Second, these stations are suitable for monitoring routes used by operators to by-pass fixed weigh scales, thereby targeting enforcement efforts and improving compliance. The report states that virtual weigh stations are “cost-effective” for size and weight enforcement and are “particularly effective” in urban areas where fixed weigh scales are uncommon.
Clough Harbour and Associates LLP (2006, p. 19) perform a review of license plate recognition (LPR) technologies for the New York State Department of Transportation. They conclude that LPR “is not ready for, and in fact may never be best suited for mainline screening.” The authors recommend that LPRs be installed as part of virtual WIM sites but used primarily as a data collection device. They also indicate that funds set aside for LPR screening would be better spent on regional transponder enrollment efforts as they “will always offer a safer more accurate method of commercial vehicle screening.”
Rooke et al. (2006, p. 38) identify six Use Cases for the EU’s project REMOVE which seeks to provide a framework for WIM systems to reduce danger and damage caused by overweight vehicles. Use Cases are used to define the behavior of a system used for enforcement. They are listed below by level of technical difficulty or technical integration (beginning with the least difficult):
- Human selectionis the traditional way of enforcement where officers use their experience to select potentially overloaded vehicles. No WIM devices are used in this application.
- Statistics and planninguses data collected from WIM systems to target enforcement activities temporally and increase the efficiency of enforcement resources. This also includes the measurement of damage to the infrastructure.
- Pre-selectionrelies on WIM systems to select potential offenders for further inspection by static scales. Pre-selection optimizes the ratio of citations given to the number of vehicles inspected. This application includes mobile screening and VWS technologies.
- Problem solvingattempts to achieve compliance by solving the problems that underlie offenses. Problem solving can be applied two ways:
  - Direct feedback – a WIM system is used to warn passing vehicles if they are potentially overweight and directs them to off load locations.
  - Company profiling – involves collecting data and images from WIM systems of violators, using license plate numbers to identify the responsible company, and creating company profiles of their level of compliance. Based on their compliance level companies may be issued a warning letter or subject to a company visit.
- Direct enforcement uses the weight measurements from WIM systems for the direct weight enforcement of trucks similar to that of automatic speed enforcement. The threshold at which vehicles are found in violation is dependent on the accuracy of the WIM sensor and in this way “enforcement focuses on the more severe cases of overloading.”
- Intelligence involves a collection of applications and the aggregation of data collected from each of them into intelligence for policing or enforcement application.
Rodier et al. (2006, pp. 127-132) find that virtual vehicle compliance stations (i.e., VWS) can be located on potential weigh scale by-pass routes to effectively identify carriers that attempt to avoid weigh scales and to help enforcement officers target trucks with a higher probability of being overweight. Their review looks at the institutional and legal barriers of installing VWS for pre-screening and enforcement.
The authors find the following regarding institutional barriers:
- Commercial vehicle operators are generally unsupportive of VWS due to confidentiality and operating cost concerns. Operators feel like these technologies collect private information about their operations and that there is potential to use this technology to increase government regulations or impose a weight-distance tax. To help alleviate this barrier the authors recommend consulting with industry early in the process of establishing VWS to create awareness about the benefits of these systems (e.g., time and fuel savings for compliant trucks being able to by-pass scales).
- Public agencies are concerned about VWS due to the potentially high cost to implement, the lack of technical expertise to operate them, and distrust by enforcement officers about their accuracy. There are also concerns that VWS could reduce felony arrests, create a negative image of officers as “sneaky,” deprive carriers of officer discretion, and face opposition by unions due to job security concerns. Some states or regions have existing pre-clearance programs and new VWS must interoperate with these programs. To overcome these barriers the authors recommend developing an incremental implementation strategy that begins with modest technologies, training programs, and staff requirements and ensuring proper communication and coordination between different government agencies and personnel.
The authors find the following regarding legal constraints:
- There are concerns from commercial vehicles operators that certain constitutional rights and protections may apply to automated enforcement programs; however, the authors find that VWS do not violate constitutional rights and freedoms.
- Amendment to state law is often required to use VWS for automated enforcement and may be required for non-voluntary pre-screening applications (e.g., amendments that ensure business confidentiality). However, state laws may not require amendment for voluntary pre-screening applications.
The report discusses program design elements to consider when implementing a VWS as follows:
- Vehicle owner versus driver citations: If VWS are used for enforcement (as opposed to screening), issuing a citation to the registered vehicle owner based on the license plate (as opposed to issuing a citation to the driver) reduces the enforcement effort, limits the infraction to a civil penalty, and can be less effective in preventing future violations. If citations are issued to the driver (as opposed to the registered vehicle owner), the effort to match the identity of the driver to the photo taken at the VWS becomes onerous and often inconclusive; however, the infraction can become a criminal offense which serves as a much stronger deterrent for future violations.
- Fixed versus mobile cameras: Compared to mobile manned cameras, fixed unmanned camera locations are usually less costly to operate, can be operated 24 hours per day, and have a smaller footprint which may allow them to operate in more locations. However, mobile manned cameras provide better geographic coverage.
- Placement of VWS: The authors recommend installing VWS only on routes with a significant violation problem or routes that could be used to by-pass a weigh station.
- Enforcement threshold: If VWS are used for enforcement, states should set a threshold that is higher than the legal weight but below which they do not issue tickets to account for potential inaccuracies of weighing equipment.
- Responsibility and authority for administering and operating VWS: Legal challenges can arise if the state leases the video monitoring equipment and services necessary to operate the program from a vendor. Citations can be dismissed in court if the vendor is paid by the number of tickets issued, if vendors are allowed to select enforcement locations, or review tickets.
The researchers suggest the following steps to address stakeholder barriers to implementation for using VWS for screening and enforcement:
- “Start with smaller, less costly, and less controversial programs.
- Establish multiagency working groups early in the process.
- Include the judiciary in working groups if automated enforcement is being considered.
- Involve the Commercial Vehicle Operations (CVO) industry early in the planning and implementation process through advisory groups.
- Conduct targeted educational outreach efforts for agencies and the CVO industry.
- Document and communicate the costs and benefits of the program.”
Honefanger et al. (2007, pp. 2-5, 39) evaluate technologies and procedures used for commercial vehicle size and weight enforcement in six European countries as part of an FHWA report. They find the following:
- Two of the six countries use technology for vehicle size enforcement that includes an automated profile measuring device and a gantry laser scanner. For speeds less than 10 km/h these systems provide an accurate dimensional picture suitable for legal enforcement. In high-speed applications they can be used for pre-selection.
- Bridge WIM systems have been successfully implemented in Slovenia, are undergoing tests in France, and have sparked interest in other EU countries. Slovenia has found most success with WIM systems on short, stiff bridge structures.
- Piezoquartz or piezoceramic WIM sensors have been consistently used for roadway applications in the European countries who took part in the scan.
- The accuracy of WIM systems is sufficient for pre-selection but not for direct automated enforcement. The Netherlands credits their pre-selection process with increasing officer efficiency from 40 percent to 80 percent (citations issued relative to vehicles stopped). Their pre-selection system includes piezoquartz WIM sensors in the two right-most lanes, two cameras on each side of the road to capture vehicle images, a camera above each lane to capture license plate numbers, and electronic loops and cameras in the third lane to capture bypassing vehicles. The Netherlands also utilizes the data collected from their pre-selection system to direct advisory notices of non-compliance to carriers consistently in violation of TSW regulations. These advisory notices are thought to be more effective than roadside inspections because a “single contact can reach companywide rather than a single driver.” Both the Netherlands and France are researching the accuracy of multiple-sensor WIM systems for direct enforcement. While it was not observed as part of the study, the United Kingdom, Belgium, and Germany are reportedly already using low-speed WIM systems for direct enforcement.
The report identifies seven specific implementation opportunities from European countries that would have the greatest potential benefit for commercial motor vehicle (CMV) enforcement in the U.S. Four of these implementation opportunities involve enforcement technologies.
- Slovenia bridge WIM: This involves weight-detection instrumentation installed under the bridge deck without disrupting traffic flow on the bridge. Once bridge deck substructures have been instrumented they can be easily removed and installed elsewhere on a rotational basis. The selection of a suitable bridge and the calibration of the B-WIM sensors may involve a high level of expertise.
- Swiss heavy goods vehicle control facility: This facility pre-selects CMVs using a HS-WIM combined with video technology. Potential violators are intercepted for static weighing while an overhead gantry fitted with laser scanners measures CMV width and height simultaneously.
- Prescreening for mobile enforcement: While the U.S. uses this approach to varying degrees there is a need for a comparative analysis with European state of practice.
- Applying WIM for direct enforcement: French officials are leading the way to overcome the institutional barriers that prohibit the use of low-speed WIM technology for direct enforcement while the Dutch are focused on acceptance of high-speed WIM technology.
Finally, the report notes that benefits from enforcement technologies currently used are not yet “precisely quantified.” The most common quantified benefit relates to enforcement efficiency calculated as the number of overweight citations per total trucks inspected. Further benefits may be realized by the implementation of high-speed WIM systems for direct truck weight enforcement, although, as of 2007, both France and the Netherlands indicate that such systems are five to 20 years in the future.
Jacob and van Loo (2008, p. 33) conclude that the two technologies which are able to fulfill the requirements for enforcement in the traffic flow are the multi-sensor (MS-) WIM and the bridge (B-) WIM. The requirements for WIM accuracy, defined as class A(5) of the COST323 Specification, are ± 5 percent for gross weights, ± 8 percent for axle group loads, and ± 10 percent for single axle loads with a confidence level greater than 96 percent. The use of these technologies for vehicle weight enforcement depends on the legal certification of high speed (HS-) WIM systems.
- MS-WIM systems can only achieve class A(5) tolerances if they are set up in arrays of eight to 16 sensors. This requires highly efficient algorithms, accurate and reliable strip sensors, powerful calibration procedures, and detailed quality assurance.
- Bridge-WIM (B-WIM) systems have been shown to achieve class A(5) tolerances on some types of bridges for GVW and axle group loads. The benefits of B-WIMs are that they are almost undetectable by drivers and do not require lane closures for installation and maintenance.
Jones (2008, p. 265) investigates the effectiveness of combining high-speed WIM sensors with overhead mounted automatic number plate recognition (ANPR) cameras to better identify vehicles in violation of TSW regulations in the United Kingdom. This system is connected to an ANPR database containing individual permitted maximum axle and gross weight limits for all U.K. registered trucks, buses, and coaches. This connection enables the system to classify vehicle configurations that are difficult for WIM sensors to classify and has had an “enormous benefit.” The weight threshold for potential violators was set at eight percent overweight by axle or GVW. This results in an average of 240 overweight alerts per day of which six percent are inspected due to staffing limitations. The research finds a 90 percent overload prohibition issue rate.
Marchadour and Jacob (2008, pp. 268-271) describe the development and implementation of a WIM network for enforcement in France. They tested low-speed WIMs (maximum vehicle speed of 4.5 km/h) installed on a concrete slab (36 m by 4.5 m) and found that they could be used for direct enforcement and could be installed, removed, and deployed at different sites. They also tested high-speed WIMs (maximum speed not specified) and found that they were inadequate for direct enforcement but useful for screening potentially overweight trucks.
The authors develop a national WIM network with three objectives:
- Pre-select and identify overloaded or speeding trucks prior to a weigh scale station
- Identify frequently overloaded carriers
- Gather statistical traffic data to determine the most overloaded road sections and time periods
To achieve these objectives, the researchers installed video-WIMs at selected sites upstream of a weigh scale which collected the following information:
- Vehicle classification (22 categories)
- Axle loads and GVW
- Speed and length
- License plate information
These systems identify trucks that are potentially overloaded or speeding and send the data to a central server and to officers at the downstream weigh station. If officers are on duty, they use the data to select vehicles to inspect. These data are centrally stored and analyzed to identify frequently speeding or overloaded carriers.
Ramseyer et al. (2008, pp. 41-45) conduct a survey of all 48 contiguous states concerning enforcement and compliance with 38 states providing responses (although not every question was answered by each respondent). The survey finds the following:
- 31 of 38 respondents indicated they have WIM systems for truck weight enforcement.
- 16 of 29 respondents indicated they use virtual enforcement (which normally involves a WIM and an image capture system); 13 do not, and nine did not respond.
- 21 of 26 respondents indicated they use an electronic by-pass system (which normally involves a WIM and other vehicle identification technologies placed in advance of a fixed weigh scale); five do not and 12 did not respond.
Stanczyk et al. (2008, p. 290) test a VWS in France for accuracy. The authors recorded an accuracy of B(10) according to COST323 specification which is acceptable for pre-screening. They report that 96 percent of pre-selected vehicles were overloaded.
Cambridge Systematics (2009a, p. 2-1 to 2-11) interviews nine states that are at the forefront of the deployment of roadside technologies. The report indicates that data from traffic monitoring WIM systems can be used for the informed placement of future WIM systems to aid in enforcement activities and to identify the most productive locations, days, and times for enforcement activities. This can be accomplished by quantifying factors temporally such as truck traffic volume and the frequency of overweight trucks. Additionally, despite deployment of technology for pre-selection, enforcement activities are still limited to the number of enforcement personnel on duty at any given time in a region because citations can only be issued once a human weighs a truck.
Specifically, the report describes the following standard applications of roadside technologies:
- Traffic monitoring WIM systemsare primarily used for planning activities but can help target enforcement resources.
- Mobile screening at WIM sitesrequire that the WIM system has wireless connectivity so that an enforcement officer can physically monitor the real-time WIM data on a laptop from the roadside. The officer must be close enough to the WIM site to visually match the CMV with its WIM data. Potential violators are intercepted for further inspection at a stationary weigh station or a mobile weigh station.
- VWSconsist of a mainline WIM system, high-speed communication, and a camera system that eliminates the need for an officer to be on site to match the CMV with its WIM data. VWS can be enhanced with optical technologies that have AVI capabilities that may be integrated with additional information from safety and vehicle databases.
- Fixed site-based mainline weight screeningrelies on a mainline WIM system to screen CMVs traveling at highway speeds for weight compliance as they approach a weigh station. Potential violators are signaled to pull-in to the station for further inspection. When coupled with an electronic screening or bypass system, CMVs may be verified for bypass eligibility based on their weight, safety, and credential information.
- Ramp sorting utilizes a WIM system on weigh station ramps to screen CMVs by weight as they approach weigh stations travelling at low speeds. Once CMVs are weighed they are signaled to either proceed to the static weigh scale or to return to the highway via a bypass lane. WIM sensor accuracy is higher for ramp sorting applications than mainline WIMs due to lower travel speeds.
The report provides the following findings concerning WIM systems:
- The costs of WIM systems (per lane) based on actual implementation experience in the U.S. is as follows: piezoelectric—$16,000; quartz piezoelectric—$29,000; bending plate—$40,000; and single load cell—$87,500. The more expensive systems are found to be more intrusive to the pavement structure but have an increased service life. The accuracy of the piezoelectric WIM is less than the other technology devices at 85 percent compared to 95 percent.
- A typical weigh station can cost anywhere from $12 million to $300 million depending on the land purchase requirement. Alternatively, based on fund requests from the FMCSA from 2006 to 2008, VWSs cost from $300,000 to $1,400,000 depending on additional enhancements like AVI technologies. One state indicated that the cost to upgrade an existing WIM site with mobile screening capabilities was marginal. Many states are choosing to deploy VWS and mobile screening due to the “increased scope of enforcement activities at less cost and staff than are required by weigh stations operations”.
- Motor carriers express concerns about data generated from roadside enforcement activities. The concerns include data retention time, usage beyond tangible goals in the public’s interest, and data being leaked to their competitors
In a 2009 state of the practice report for the FHWA, Cambridge Systematics (2009b, p. 2-6) states that the use of WIM technology for direct enforcement activities is “not a target of the FHWA or state Departments of Transportation (DOTs) or law enforcement agencies.” Rather WIM technology is commonly used for the pre-selection of vehicles that have a higher risk of being non-compliant, and effectively reduces the amount of compliant trucks that are inspected. Further, they have been developed to virtually screen vehicles in real-time at inspection stations that are unstaffed.
The report (p. 3-3) discusses the recent increase in WIM use on inspection station approach ramps in the U.S. This configuration takes advantage of a commercial vehicle’s reduced speed to obtain more accurate axle weights. Inspection officers set the weight thresholds and vehicles that exceed that threshold must stop for further inspection. Four of the nine states that participated in the study have five or more of these weigh stations.

In particular, the report identifies Washington State’s Commercial-vehicle Roadside Information Sorting System (CRISS) as an example of how high-speed WIMs (HS-WIM) are utilized for fixed weigh station operations. Washington State has installed WIM sensors coupled with cameras at 14 of its weigh stations that provide coverage for over 80 percent of the commercial vehicle fleet. The CRISS software provides inspection officers with an image of each commercial vehicle along with its weight information and an algorithm determines if there are potential axle weight violations.

Finally, the report (p. 4-3) discusses the use of WIM systems for mobile screening as a form of pre-selection for enforcement. Inspection officers at the roadside receive real-time vehicle weight information wirelessly from a WIM system located upstream and use it to intercept potentially overweight trucks for further inspection. This type of enforcement pre-selection can be achieved at a relatively low cost as any WIM system can be upgraded to have wireless connectivity. Mobile screening sites require WIM sensors, a roadside processor, wireless connectivity, a data receiver in the patrol car, and a laptop with the appropriate software. The inspection officer must be near enough to the WIM site to be able to visually identify vehicles as they pass over the sensors. The authors find that states consider mobile screening to be “well worth the costs” particularly when existing WIM systems are upgraded.

Similar to mobile screening, VWS rely on WIM systems to provide weight information of vehicles but they are enhanced by a digital imaging system to identify potential violators. This reduces the need for permanent on-site staff as potential violators can be identified by officers remotely from multiple images of the vehicle. Indiana estimates the cost to retrofit existing WIM sites to VWS to be approximately $30,000. The digital imaging system can be further enhanced with optical character recognition (OCR) software to relieve the need for manual vehicle identification by providing a license plate number. This is particularly important in areas with high truck traffic volume.
Cambridge Systematics (2009c, p. ES-19, 3-7) lists the following benefits of license plate readers and other AVI technologies: (1) enable officers to target likely offenders; (2) improve data collection; and (3) enable timely access to safety, credentials, and criminal records.
The report also indicates (p. 3-7) that on-board scales can be used to monitor truck weight. Information can be extracted from the devices for enforcement purposes by directly plugging into the device or via a wireless connection. The devices help expedite the inspection process at weigh scales thereby reducing enforcement costs. The accuracy of these devices is “still questionable.” In addition to weight, on-board equipment can also be used to monitor brake and tire conditions, lighting, steering, suspension, exhaust, and horn operation.
Hahn and Pansare (2009, pp. xiv-xvii) provide detail on Maryland’s implementation of VWS, which are intended to augment current enforcement activities at fixed facilities and mobile patrols. In Maryland, the goals of the VWS pilot project are: (1) to provide a platform for helping law enforcement personnel target enforcement activities; (2) to develop a “stable, accurate, and standard platform for rapid deployment at other statewide locations”; (3) to determine, from a research perspective, whether a relationship between weight and safety exists; and (4) to provide recommendations and guidelines in expanded deployment of the VWS concept.
The pilot project deployment involved two phases of tests. The first phase involved a predefined set of vehicles and confirmed that the VWS met relevant technical requirements. The second phase involved a set of on-road vehicles and also confirmed that the VWS met technical requirements (except for the gross weight requirement which was “not met completely”).

Data collected by the VWS provide “valuable clues to focus their inspection efforts during time periods that suggest more over weight and/or over height violations.” No relationship between weight and safety violations was observed. The study concluded that the VWS “improved the effectiveness of [commercial motor vehicle] selection methods significantly over a traditional method relying on random selection.”

[A follow up discussion with Maryland State Police and Maryland State Highway Administration in August 2013 revealed that current VWS and future VWS (22 total VWS stations by 2017) will incorporate Drivewyze Inc.’s PreClear service. Drivewyze is an “inspection site bypass system which adds transponder-like functionality to tablet computers and smart phones, and enables enforcement officers to electronically pre-screen trucks traveling at highway speeds (Transport Topics 2013, p. 15).”]
Hanson et al. (2010, p. 8) evaluate the percent of commercial vehicles being required to report to an inspection station in Nova Scotia, Canada before and after the installation of an advanced WIM sorting system was implemented in 2007. They found that after implementation the inspection station required 23 percent of commercial vehicles to stop versus the 60 to 70 percent that were required to stop previously. There was also a 27 percent decline in citations from 2005 to 2007 after implementation.
The authors also document (p. 10) the use of a VWS in Newfoundland and Labrador, Canada for follow-up enforcement of commercial vehicle violations. The VWS system includes a quartz WIM sensor and multiple cameras that are triggered by inductive loops. The cameras are configured to only collect images of the violating commercial vehicles that are identified in real-time by the WIM device. The data are filtered and used to notify carriers with “non-compliance tendencies” that they may be subject to further enforcement.
Kwon et al. (2010, p. 6) test a high-speed WIM (HS-WIM) system in Korea that includes a “wandering sensor” to detect the relative position of the driving vehicle in the lane and to increase the accuracy of vehicle classification for lift axle configurations. This system is found to be effective at detecting five-axle trucks with a lift-up axle. The HS-WIM sensor accuracy is tested following European COST323 WIM specification test conditions. The accuracy of the system is within 5 percent for gross weight error but receives a COST323 accuracy of class B+(7) due to the error range of the axle group performance.
Australia’s National Transport Commission (2011b, p. vi) investigates the deployment of on-board mass technology as a means of supporting truck weight enforcement in Australia. The Commission evaluates three options, including “business as usual,” mandatory installation, and voluntary installation. They conclude that the use of on-board mass systems should be “on a predominantly voluntary basis” by carriers as a means of meeting weight compliance regulations. Mandating the use of a specific technology restricts carriers in how they may develop cost effective weight compliance management systems. However, it is understood that repeat violators may need more prescriptive measures.
Lee and Chow (2011, pp. 92, 99, 102) develop a simulation model to estimate the effectiveness of e-screening (i.e., screening trucks upstream of an inspection station using WIM) and the effect of transponder adoption. The researchers apply the model to a small weigh scale station in Canada (Port Mann, British Columbia) with a short queuing area and high truck volumes. Transponders are used to automatically send the credentials of the truck and driver to the weigh station as the truck approaches the weigh scale. This information helps the enforcement officers determine if the truck should be inspected for purposes other than weight. The authors find that e-screening improves overweight enforcement and that these improvements are enhanced as transponder adoption increases. The model shows an enforcement rate of 99.0 percent when 75 percent of the trucks have transponders and 49.9 percent when none of the trucks have transponders. Overall the study finds that at least 20 percent of the trucks passing the station must have transponders to show any type of enforcement benefit.
OECD (2011, pp. 290-292) indicates that the WIM technology for direct truck weight enforcement remains an emerging practice in most countries today. That is, an overweight measurement recorded dynamically at high-speed by a WIM device is not normally used as the sole evidence of an overweight violation. Nevertheless, WIM applications for enforcement include:
- the use of WIM as a pre-screening tool to identify and direct vehicles likely to be overweight to a traditional static weigh scale site for weight validation;
- WIM monitoring to identify times and places in which overloading may be more problematic, so that enforcement activities can be better targeted; and
- WIM monitoring of bypass routes to support other enforcement activity.
The report also comments on several other truck weight enforcement technologies:
- On-board weighing systems have been used by carriers for certain industry sectors as a tool to help avoid inadvertent overloading. In Australia, recent findings indicate that the accuracy levels and tamper-resistant capabilities of these technologies are now sufficient for regulatory enforcement applications.
- The Australian Intelligent Access Program uses satellite-based vehicle position and tracking technologies to ensure that trucks adhere to relevant highway network restrictions (which are defined based on TSW limits).
- Data capture, storage, analysis and reporting technologies will enable “more effective compliance and enforcement” through better targeting of high-risk drivers and operators and automated enforcement of violations without human intervention.
CDM Smith (2012, p. 4) reviews multi-state weigh station pre-clearance systems for Minnesota. Trucks that are part of pre-clearance programs are fitted with transponders that communicate their size, weight, and identification to roadside readers. Additionally, their unique identification is matched against a database that contains information on the recent safety and credentials of the carrier and truck. If the data indicates compliance then the truck is given authority to by-pass the scale. The authors identify two multi-state pre-clearance systems available to state DOTs and note that two states have developed their own systems. However, many states are moving towards VWS as they do not require transponders in trucks for pre-clearance. The two multi-state pre-clearance systems are described briefly below:
- PrePass® has adopted the Inspection Selection System (ISS) developed by the FMCSA as its primary criteria for safety clearance. Many PrePass® systems do not include mainline WIM sensors. PrePass® operates in 31 states with over 305 sites.
- NORPASS operates in eight states but was giving consideration to migrate their system to PrePass®.
Hitchcock et al. (2012, p. 59) test the SiWIM system, a bridge WIM system developed by CESTEL, for enforcement application in Alabama. They find that: (1) SiWIM systems can be installed in one day and calibrated in an additional day after completing ten acceptable calibration runs in each lane; and (2) a maximum of two lanes on a bridge and steady travel velocity improves successful vehicle capture (rigid short span bridges are preferred).
Jones (2012, pp. 4-6) describes a technology used in New South Wales in Australia called Truckscan. This technology pre-screens trucks using WIM and license plate readers to identify high risk trucks that should be stopped for inspection and low risk trucks that can by-pass an enforcement facility. Technologies such as WIM and others are used to determine the vehicle's weight (axle and gross), height, length, classification, and speed. A video camera captures a vehicle's license plate which is used to determine the vehicle's status in a national database, its registration number, and historical information (e.g., citations). Truckscan considers 36 criteria in establishing the risk of a truck and uses an algorithm to compute a risk score. The time to compute the risk is about six seconds.
McBride and Kirby (2012, p. 8) indicate that transport operators who elect to voluntarily share their electronic vehicle data may be held to alternative enforcement intervention. This may include authorization to by-pass active weigh sites with a view to increasing productivity and encourage compliance. Electronic vehicle data could include position, road user charges, engine management, and driver identification data.
The authors also identify (p. 39) three high-level concepts of operation that utilize strategic electronic monitoring (SEM): (1) direct automated enforcement, (2) automated inspection with targeted intelligence driven enforcement, and (3) electronic screening with low-speed/static inspection. They indicate direct automated enforcement as the most direct and productive high-level concept that utilizes SEM. Direct automated enforcement relies on road side technology to detect vehicles operating outside a specified range and automatically notifies the operator/driver/owner with an infringement notice requiring no police enforcement resources. The implementation of such a concept requires significant political will as it will most likely occur simultaneously with changes to current governing laws for heavy commercial vehicles.

The authors recommend (p. 57) SEM that consists of these primary high-speed technologies:
- An evidential grade high-speed WIM system that meets the updated international WIM Specification standard OIMLR134.
- 3D cameras equipped with infra-red and color capture that utilize image processing software to accurately calculate vehicle characteristics including speed, following distance, vehicle classification (height, width, length), among others.
- 2D cameras for side views to confirm axle groups. When coupled with automated number plate recognition systems, these systems can identify vehicles that avoid inspection stations.

4.3.4 Enforcement Effectiveness and the Judicial System

In addition to the foregoing assessments of on-road enforcement methods, the literature discusses how two aspects of the judicial system—the severity of sanctions and the use of relevant evidence—influence enforcement effectiveness.

The severity of sanctions for overweight trucking has been found to influence the effectiveness of truck weight enforcement programs and offers an alternative strategy to increasing on-road enforcement intensity. TRB (1990, pp. 135, 143) contends that to be “effective,” the enforcement of weight regulations requires that they be uniform, relatively simple to comprehend and apply, and that penalties are sufficiently severe so as to deter non-compliance. The report also observes that “because of the economic incentives for illegal overloading, honest truckers are at a disadvantage in competing for work with those who violate the law.” From this perspective, any non-compliance would appear to be inappropriate—not so much because of its economic effect on infrastructure as from its implications for “the even playing field.” Similarly, Cambridge Systematics (2009c, p. ES-10) indicates that current enforcement levels and low fines provide an “incentive for noncompliance.” This conclusion is based on public outreach conducted as part of Wisconsin’s TSW study.

Strathman (2001, p. 7) conducts a statistical analysis to develop linear regression models that relate enforcement intensity, fines, truck volume, and value per ton. The author finds that increasing enforcement or increasing fines have about the same effect in deterring overweight vehicles; however, the effect of enforcement is primarily attributed to mobile patrols. The author concludes that the most cost-effective way to reduce overweight vehicles is to increase fines since this has about the same effect as increasing enforcement levels but without the extra costs of enforcement.

Relevant evidence laws have seen limited use in the United States, though they are recognized as one option to improve TSW enforcement program effectiveness. Citing Minnesota as an example, the USDOT (2000, p. VII-12) indicates that bills of lading, weight tickets, and other relevant documents are used as legal evidence to establish an overweight violation. Enforcement occurs through an audit of shipper or freight forwarder files, with legal action possible against the driver, shipper, owner, or lessee. The program is built around the law that all receiving sites in Minnesota must retain weight bills and allow access to enforcement officers within 14 days of when the shipment was received (Cambridge Systematics 2009b, pp. 4-6). While the use of relevant evidence laws has been successful in Minnesota, pilot programs in the 1990s in four other states (Iowa, Louisiana, Mississippi, and Montana) were unsuccessful because of industry opposition to the required legislative support. The report identifies the administrative system used in Georgia to process weight citations as an alternative to the court process (USDOT 2000, p. VII-12).

4.4 Regulatory Changes and the Effectiveness of TSW Enforcement

The literature identifies a relationship between changes in TSW regulations and the effectiveness of TSW enforcement. TRB (2002, pp. 171, 173-174) suggests that a lack of sufficient enforcement impedes the effectiveness of TSW regulatory reform. Regulatory complexity or the introduction of trucks that may be easier to overload are examples of enforceability problems that may occur due to reforms. Similar problems may result from permit programs or exceptions that continue to grow and become more complex, particularly since data about the number of legal permitted loads operating in excess of 80,000 lbs. and the distance these loads travel are limited.

In two separate state-based TSW studies (Wisconsin and Minnesota), Cambridge Systematics (2006, p. 20) (2009c, p. ES-17) suggests that changes in TSW laws may necessitate additional enforcement resources (particularly inspection personnel) and that the complexity of TSW laws “complicate compliance”. Similarly, Carson (2011, p. 38) asserts that TSW regulations “should be uniform in their scope and relatively simple to comprehend, apply, and enforce.” Regulations that are too complex or which contain numerous exceptions lead to lower levels of enforcement and prosecution.

Woodrooffe et al. (2010, p. 30) also identify enforcement resource implications of changes in TSW laws. In a review of TSW regulation in Canada, the authors indicate that certain provinces had to replace their platform scales to accommodate tridem axle groups (with a 3.66 m spread), which were allowed nationwide for the first time after the Memorandum of Understanding on Vehicle Weights and Dimensions was implemented in Canada in 1989.

Pilot programs offer a potential opportunity to examine the relationship between regulatory change and enforcement effectiveness. The FHWA (2012a, pp. 21-22) investigates enforcement levels and overweight axles as a potential contributor to truck crashes as part of the Vermont pilot program. This program saw an increase in TSW limits on Vermont’s interstate highways for a one-year period, including allowance of a 6-axle tractor semitrailer limited to 99,000 lbs. GVW. The report indicates that, on average in Vermont, three percent of single axles exceed the 20,000-lb. limit and 13 percent of tandem axles exceed the 36,000-lb. limit in effect during the pilot program. The overweight observations may or may not involve pilot vehicles or vehicles operating under permit. In addition, an analysis of crash data reveals that approximately half the carriers involved in the pilot program were involved in crashes during the program, though these crashes may not have involved pilot program trucks.

In a related 6-month report on the Maine and Vermont pilot program, the FHWA (2012b, pp. 2-3) describes preliminary findings of the program with a focus on bridge and pavement impacts. The program allows for gross vehicle and axle weights on interstate highways beyond normal federal limits. In Maine, the program enables operation of six-axle tractor semitrailers up to 100,000 lbs. and tandem axle weights up to 46,000 lbs. for certain commodities. In Vermont, the program enables operation of six-axle tractor semitrailers up to 99,000 lbs. and tandem axle weights up to 39,600 lbs. (inclusive of a 10 percent weight tolerance). The report does not make direct reference to enforcement issues, but does mention the need for increased monitoring of bridges using WIM devices. Regarding pavements, the increased vehicle loadings would cause additional pavement damage which could be limited through industry co-operation and increased enforcement; no details are provided as to the extent of benefit that may be gained by industry co-operation and increased enforcement. Conclusive findings are expected after the full implementation of the program.

ADDENDUM – Adopted Australia Compliance

This appendix provides a chronological, document-by-document summary of literature related to alternative approaches for achieving compliance—principally those adopted in Australia.

Johnstone (2002, pp. 24, 25, 31) notes that road transport regulation, including TSW regulation, has historically necessitated ensuring regulatory compliance with prescriptive requirements. On-road enforcement directed at drivers and operators has been the primary instrument used to achieve compliance with these regulations. This approach has been criticized because it ignores the responsibility of other parties within the logistics supply chain for a non-compliant event and it has applied a penalty structure inadequate for deterring non-compliant behavior. In Australia, this criticism has led to the adoption of the chain of responsibility principle in which all parties within the trucking contractual chain have some duty to ensure compliance (including compliance with TSW regulations). From a legal perspective, this duty must be established through a causal nexus between each party’s activities and a non-compliant event.
McIntyre (2002, pp. 53-55, 60-64) describes the (Australia) National Road Transport Commission’s (NRTC) approach to enhancing a compliance culture. The author asserts that a “nationally consistent, well-targeted approach to enforcement is an important component of the Commission’s strategic framework for compliance reforms.” However, conventional (sanctions-based) enforcement is considered only one of a number of additional strategies needed to create a sustainable compliance culture for the trucking industry. Additional strategies, include:
- Privileges and incentives-based strategies such as accreditation-based schemes;
- Training of enforcement officers and industry;
- Education and communication strategies;
- Monitoring of enforcement effectiveness; and
- Ongoing research to ensure programs adjust to technological, societal, and legal developments.
A combination of approaches enables a more proactive (rather than reactive) means of achieving compliance. The author cites the following reasons why a reactive, enforcement-oriented response is insufficient:
- “The effectiveness of enforcement-based strategies to modify road user behavior is dependent on there being a perception that there is a real possibility that breaches will be detected. However, there are simply not enough policing resources to cover the whole road network, and the chance of apprehension at any one time is low.
- Fines, no matter how high, will not have a sufficiently deterrent effect when the chance of detection is slight but the potential profits from offending are high.
- Targeting only the driver and owner of heavy vehicles (the ‘soft’ enforcement options) will not deter the many ‘off-road’ parties who play a significant role in breaching the road laws.”
Australia’s NRTC (as of 2002) proposed a reformed legislative approach to address these issues. Specifically, the legislation incorporates the chain of responsibility principle (including the parties involved in consigning, loading, carrying, driving, receiving, and packing) and the requisite enforcement powers to support it (such as compliance audits and the legal acceptability of various types of evidence). In addition, it provides a risk-based categorization of offences to account for varying severity and to enable distinctions between unintentional offences and those committed for commercial gain, between individuals and corporate bodies, and between first time and habitual offenders. The reforms also adjusted penalty structures.
McKeachie and McCrae (2002, p. 116) describe the various elements of the “enforcement pyramid,” which depicts a series of progressively more aggressive enforcement tools (moving from bottom to top), all of which are directed at achieving regulatory compliance (though not applicable only to the trucking industry). Starting at the base, the pyramid includes: persuasion and education, administrative penalties, civil penalties, criminal penalties, suspension, and revocation.
Leyden et al. (2004, pp. 3-9) describe Australian approaches to heavy vehicle accreditation and compliance. The authors recall that in 1997 the Australian Transport Ministers approved a voluntary accreditation system (National Heavy Vehicle Accreditation Scheme) where operators who apply for accreditation must have systems and procedures in place that will provide evidence of compliance. Accredited operators are subject to fewer roadside inspections and are instead subject to an ongoing audit regimen to ensure compliance is being maintained (p. 3). The authors state that adopting accreditation systems and providing various benefits to accredited operators (e.g., higher weight limits, broader access to certain road networks) can serve as a powerful mechanism for compliance and also increase the efforts of regulators and the documentation they must keep to respond to legal challenges by operators who have been denied accreditation. They also briefly describe the chain of responsibility concept and explain that any entity that exercises control over any of the following activities are subject to joint and several liability for overloading trucks:
- Consigning
- Loading
- Carrying
- Driving
- Receiving
Under this enforcement and compliance approach, violators (e.g., consignors, carriers, receivers, etc.) must demonstrate that they took reasonable steps to avoid breaching weight limits or that they neither knew nor reasonably ought to have known of the breach. This encourages the installation of documentation systems to achieve and demonstrate compliance. The law also allows senior officers of a company (e.g., director, manager) to be punished for committing a road law offence or encouraging a truck to operate overweight.

Australia created three categories of weight violations:
- Minor (up to five percent above legal limit)
- Substantial (up to 20 percent above legal limit)
- Severe (above 20 percent of the legal limit)
Australia also created a hierarchy of sanctions that provided flexibility and options for disciplining violators. This recognized that conventional fines may not be a deterrent for all parties in a logistics chain. Following is the hierarchy of sanctions in order from least punitive to most, where the first three are administrative sanctions and penalties and the remaining are court sanctions and penalties:
- Improvement notice
- Formal warning
- Infringement notice
- Fine
- Commercial benefits penalty
- Supervisory intervention orders
- Orders affecting licenses and registration
- Prohibition orders
Australian law also allows the courts to issue a compensation order to an offender which compensates the road authority for loss or damage to any road infrastructure caused by the offense.

The authors find that enforcing the chain of responsibility has led to significant improvements in documenting heavy loads, and that this documentation helps audit the evidence produced by accredited carriers. Australia is also finding that more shippers and receivers are including a requirement to be accredited into their service contracts to help mitigate their risk under the chain of responsibility.
Germanchev and Bruzsa (2006, pp. 2-10) describe a hybrid testing method to prove the compliance of heavy vehicles. Based on experience with Performance Based Standards in Australia, the authors find that the best method to assess the performance of trucks is a hybrid method consisting of simulation and field testing. This approach inputs the specifications of truck configurations into a simulation model to predict how the vehicle will operate and behave under different conditions. The truck configuration is then tested in a private testing facility which replicates the driving conditions of the model. Field measurements are recorded and used to calibrate the model. Once calibrated, the model is used to determine the predicted performance of the truck configuration on different types of roadways in Australia to determine where this truck will be permitted to operate. The authors find that the combination of simulation and field testing is a robust and accurate approach to predict the actual performance of a vehicle configuration under different conditions.
Australia’s National Transport Commission (2007, pp. 1, 4) provides a report outlining the National Heavy Vehicle Enforcement Strategy, aimed at promoting consistent, effective and efficient enforcement in heavy vehicle transport law in Australia. The strategy follows the 2003 passage of a bill that, among other items, recognized the chain of responsibility principle within TSW enforcement. As of 2007, however, not all Australian jurisdictions had adopted the bill’s provisions; hence the development of the national strategy. The strategy identifies the following objectives to achieve the national compliance outcome:
- Intelligence-driven enforcement requires information systems that help target enforcement activity and improve detection of violations.
- Consistent, effective, and efficient enforcement practices emphasize co-operation between enforcement agencies and promote a more cohesive relationship between the industry and the regulator.
- Co-operation and trust between industry and the regulator should be fostered to improve compliance.
- Officer training designed to enable confident execution of enforcement tasks.
- Improved communication between enforcement agencies provides an integrated means of recognizing and resolving issues.
Walker (2010, pp. 17-18) discusses Australia’s evolving heavy vehicle regulatory approach, in particular recent implementation of the National Heavy Vehicle Accreditation Scheme (which provides concessions for accredited carriers) and the chain of responsibility principle (which places responsibility for non-compliance on all agents within the logistics supply chain). A series of stakeholder interviews reveals that the accreditation scheme has provided opportunity for better engagement between the regulator and the operators within an innovative and flexible regulatory structure. However, not all operators are interested in participating in such a scheme. Therefore, Walker suggests the need for a two-track regulatory structure, where certain operators demonstrate compliance through the accreditation scheme, while others remain subject to prescriptive regulations and more traditional enforcement. A two-track system has the potential to incentivize compliance and build on innovations already present within the accreditation scheme. However, risks of a two-track system include: unfair competition, complex enforcement, costly implementation, and potential abuse within the self-accreditation program.
The OECD (2011, pp. 284-288) identifies accreditation as one alternative compliance strategy. Accreditation is a voluntary or mandated arrangement in which an operator certifies compliance with specified regulatory requirements, and the regulator validates compliance through an auditing process. Accreditation schemes have been implemented for the purpose of ensuring compliance with TSW limits, as well as other requirements such as route adherence, cargo handling, and safety. In some schemes, demonstrated compliance within an accreditation scheme enables carriers to operate beyond basic TSW limits. In other words, productivity incentives are used as a means to achieve regulatory compliance for an accredited operator.

Illustrative descriptions of how accreditation schemes have been used within a TSW enforcement program follow:

Australia’s National Heavy Vehicle Accreditation Scheme is a voluntary program that allows an accredited carrier to demonstrate compliance (via auditing) and thereby be subject to less frequent on-road enforcement activities. Operators may select to be accredited for maintenance management (which exempts qualified operators from annual inspections), weight management (which allows qualified operators to increase loads), or fatigue management (which provides qualified operators flexibility in hours of service restrictions).
South Africa’s Road Transport Management System is a voluntary accreditation scheme designed to improve compliance with weight and safety-related regulations by encouraging industries to take more responsibility for improving on-road safety and limiting infrastructure damage. The scheme is viewed as an instrument which can be used by various agents in the supply chain interested in improving corporate governance.

Another alternative strategy involves the use of the chain of responsibility principle, which is described as follows:

“…all who have control, whether direct or indirect, over a transport operation bear responsibility for conduct which affects compliance and should be made accountable for failure to discharge that responsibility.”

This principle can be applied to various aspects of on-road compliance. However, a pertinent example from a TSW perspective is the penalization of a grain handling company which receives grain from overloaded trucks and rewards operators who do so.

Technological adoption and legislative reform are necessary enablers of the chain of responsibility principle. Technologies (e.g., real-time tracking, electronic on-board recording devices) now enable many aspects of a freight transport task to be monitored remotely, thereby placing additional responsibility on the operator for assuring compliance. Legislative reforms that requires all agents within a supply chain to ensure compliance or which reverse the onus of responsibility so that all parties are automatically deemed responsible for non-compliant behavior support the chain of responsibility principle.

Jones (2012, pp. 8-11) describes aspects of Australia’s new enforcement program which includes concepts such as the chain of responsibility and using technology and data to improve enforcement and compliance. To create a culture where TSW laws are nearly self-regulating, Australia is implementing the chain of responsibility concept and trying to achieve voluntary compliance. They are also introducing responsive regulation in legislation that provides regulators with a range of penalties that account for individual company risk and past performance. The lowest penalties require carriers to attend educational sessions which carry no financial impact or issue fines that are a fraction of what would normally be issued. The highest penalties can triple the fine or revoke vehicle or drivers licenses. The chain of responsibility concept has potential to be effective but the author finds that shippers were frustrated with this approach because regulators were unable to provide advice to them about how to manage their obligations when trucks were overloaded. The author concludes that the lack of policy forethought and practical guidance can hinder well-meaning intentions of the industry.
The author also finds the following:
- High-quality and timely data are necessary for regulators to differentiate between low and high risk operators and to provide incentives to compliant operators and target non-compliant operators. However, Australia does not have the system in place to do this at a national level.
- Australia is interested in providing a reward- and incentive-based system for operators to achieve compliance. Some ideas for incentives are to dedicate varying levels of the transportation spending budget to truck-related initiatives based on the level of industry compliance, reduced registration and licensing costs for compliant operators, and reduced insurance premiums.

REFERENCES

Allen, D.
—2002. “A Compliance Methodology for New South Wales.” Achieving Compliance through Strategic Enforcement, (pp. 173-187). Gold Coast, Australia.

Cambridge Systematics.
—2009a. Truck Size and Weight Enforcement Technologies - Implementation Plan. Washington D.C.: Federal Highway Administration.
—2009b. Truck Size and Weight Enforcement Technologies - State of the Practice. Washington D.C.: Federal Highway Administration.
—2009c. Wisconsin Truck Size and Weight Study. Madison, WI: Wisconsin Department of Transportation.
—2006. Minnesota Truck Size and Weight Project. St. Paul, MN: Minnesota Department of Transportation.

Carson, J.
—2011. Directory of Significant Truck Size and Weight Research. Washington, D.C.: American Association of State Highway and Transportation Officials.

CDM Smith.
—2012. Minnesota Commercial Vehicle Pre-Clearance System Evaluation. St. Paul, MN: Minnesota Department of Transportation.

Clough Harbour & Associates LLP.
—2006. Research and Analysis of License Plate Readers and Video Recognition Subsystems for Integration with the Mobile CVIEW Electronic Screening System. Albany, NY: New York State Department of Transportation.

DalPonte, G., Fortey, N., & Scrivner, E.
—2015. “Using Performance Measures to Lighten the Load—Re-thinking the Size and Weight Enforcement Program.” Transportation Research Board Annual Meeting. Washington, D.C.: Transportation Research Board.

Federal Highway Administration.
—2012a. Vermont Pilot Program Report. Washington, D.C.: Federal Highway Administration.
—2012b. Maine and Vermont Interstate Highway Heavy Truck Pilot Program: 6-Month Report. Washington, D.C.: U.S. Department of Transportation.
—1993. Overweight Vehicles - Permits and Penalties. Washington, D.C.: Federal Highway Administration.

Fekpe, E., Gopalakrishna, D., & Woodrooffe, J.
—2006. “Conceptual Framework for a Performance-Based Oversize and Overweight Permitting System.” International Symposium on Heavy Vehicle Weights and Dimensions - HVWD9. State College, PA: International Forum for Road Transport Technology.

Germanchev, A., & Bruza, L.
—2006. “Hybrid Testing Method to Prove the Compliance of Heavy Vehicles.” International Symposium on Heavy Vehicle Weights and Dimensions - HVWD9. State College, PA: International Forum for Road Transport Technology.

Grenzeback, L., Stowers, J., & Boghani, A.
—1988. Feasibility of a National Heavy-Vehicle Monitoring System. Washington, D.C.: Transportation Research Board, National Research Council.

Gu, Z., Urbanik, T., & Han, L.
—2004. “Evaluation of weigh station design and operational strategies using simulation.” Proceedings of the Transportation Research Board Annual Meeting. Washington, D.C.: Transportation Research Board.

Hahn, D., Pansare, M.
—2009. Maryland Virtual Weigh Station Final Report. Hanover, MD: State Highway Administration, Maryland Department of Transportation.

Hajek, J., & Selsneva, O.
—2000. Estimating Cumulative Traffic Loads, Final Report for Phase 1. Washington, D.C.: Federal Highway Administration.

Han, L. D., Ko, S.-S., Gu, Z., & Jeong, M. K.
—2012. “Adaptive weigh-in-motion algorithms for truck weight enforcement,” Transportation Research Part C, 256-269.

Hanscom, F.
—1998. Developing Measures of Effectiveness for Truck Weight Enforcement Activities. Washington, D.C.: National Cooperative Highway Research Program.

Hanson, R., Klashinsky, R., & McGibney, S.
—2010. “ITS technologies for commercial vehicle compliance in the Maritimes.” 2010 Annual Conference of the Transportation Association of Canada. Halifax, Nova Scotia: Transportation Association of Canada.

Hitchcock, W., Uddin, N., Sisiopiku, V., Salama, T., Kirby, J., Zhao, H., . . . Richardson, J.
—2012. Bridge Weigh-in-Motion (B-WIM) System Testing and Evaluation. Birmingham, AL: University Transportation Center for Alabama.

Honefanger, J., Strawhorn, J., Athey, R., Carson, J., Conner, G., Jones, D., . . . Woolley, R.
—2007. Commercial Motor Vehicle Size and Weight Enforcement in Europe (FHWA-PL-07-002). Washington D.C.: Federal Highway Administration.

Jacob, B., & Loo, H. v.
—2008. “Weigh-in-motion for enforcement in Europe.” International Conference on Weigh-in-Motion, (pp. 25-35). Paris.

Johnstone, R.
—2002. “The legal framework for regulating road transport safety: Chains of responsibility, compliance and enforcement.” Achieving Compliance through Strategic Enforcement, (pp. 23-44). Gold Coast, Australia.

Jones, M.
—2008. “Targeted roadside enforcement using WIM and ANPR.” International Conference on Weigh-in-Motion, (pp. 258-265). Paris.

Jones, S.
—2012. “Compliance and enforcement in Australia’s brave new heavy vehicle world.” International Symposium on Heavy Vehicle Transport Technology – HVTT12. Stockholm, Sweden: International Forum for Road Transport Technology.

Kwon, S., Park, H., Kim, J., Kang, K., & Lee, D.
—2010. “Development and application of the non-stop over-weight control system using HS-WIM.” 17th ITS World Conference. Busan, Korea: ITS Korea.

Lee, J., & Chow, G.
—2011. “Operation analysis of the electronic screening system at a commercial vehicle weigh station,” Journal of Intelligent Transportation Systems, 15(2), 91-103.

Leyden, P., McIntyre, K., & Moore, B.
—2004. “Current Australian approaches to heavy vehicle accreditation and compliance for mass limits.” 8th International Symposium on Heavy Vehicle Weights and Dimensions. Johannesburg, South Africa: Document Transformation Technologies.

Marchadour, Y., & Jacob, B.
—2008. “Development and implementation of a WIM network for enforcement in France.” International Conference on Weigh-in-Motion, (pp. 266-274). Paris.

McBride, C., & Kirby, P.
—2012. Strategic Electronic Monitoring and Compliance of Heavy Commercial Vehicles in the Upper North Island. Wellington, New Zealand: NZ Transport Agency.

McIntyre, K.
—2002. “The national road transport compliance and enforcement reforms: Creating a compliance culture.” Achieving Compliance through Strategic Enforcement, (pp. 53-102). Gold Coast, Australia.

McIntyre, K., & Moore, B.
—2002. “National Road Transport compliance and enforcement reforms: On the Road to a new national culture of compliance.” Current Issues in Regulation: Enforcement and Compliance. Melbourne, Australia: Australian Institute of Criminology.

McKeachie, J., & McCrae, J.
—2002. “Strategic enforcement: A Queensland perspective.” Achieving Compliance through Strategic Enforcement, (pp. 113-129). Gold Coast, Australia.

National Transport Commission.
—2011a. Regulatory Compliance Best Practice Review. Melbourne, Australia: National Transport Commission.
—2011b. On-Board Mass Technology Policy Framework. Melbourne, Australia: National Transport Commission.
—2009. National Heavy Vehicle Enforcement Strategy Cost Benefit Analysis. Melbourne, Australia: National Transport Commission.
—2007. National Heavy Vehicle Enforcement Strategy Proposal. Melbourne, Australia: National Transport Commission.

Office of Inspector General.
—1991. Report on the Audit of the Vehicle Weight Enforcement Program. Washington, D.C.: U.S. Department of Transportation.

Organisation for Economic Co-operation and Development and the International Transport Forum.
—2011. Moving Freight with Better Trucks. Paris: Organisation for Economic Co-operation and Development.

Quinlan, M.
—2002. “Co-operation to achieve compliance objectives in long distance road freight: A new look at an old issue.” Achieving Compliance through Strategic Enforcement, (pp. 221-247). Gold Coast, Australia.

Ramseyer, C., Nghiem, A., & Swyden, D.
—2008. Investigation of Cost Effective Truck Weight Enforcement. University of Oklahoma. Oklahoma City, OK: Oklahoma Department of Transportation.

Regehr, J.D., Montufar, J., Sweatman, P., & Clayton, A.
—2010. “Using exposure-based evidence to assess regulatory compliance with productivity-permitted long trucks.” 11th International Symposium on Heavy Vehicle Transport Technology. Melbourne, Australia: International Federation of Road Transport Technology.

Rodier, C., Shaheen, S., & Cavanagh, E.
—2006. “Virtual commercial vehicle compliance stations: A review of legal and institutional issues,” Transportation Research Record: Journal of the Transportation Research Board, No. 1966, 126-132.

Rooke, A., Shipp, C., de Groet, K., Loo, H., & Scorer, A.
—2006. Project REMOVE Final Report. Dubendorf, Switzerland: International Society for Weigh in Motion.

Santero, N., Nokes, W., & Harvey, J.
—2005. Virtual Weigh Stations in California:A Preliminary Cost-Effective Analysis. Berkeley, CA: Institute of Transportation Studies, University of California.

Siekmann, A., & Capps, G.
—2012. Heavy and Overweight Vehicle Defects Interim Report, Oak Ridge, TN: Oak Ridge National Laboratory, ORNL/TM-2012/575. November.

Stanczyk, D., Geroudet, B., Thiounn, C., & Millot, A.
—2008. “Pre-selection of overloaded vehicles.” International Conference on Weigh-in-Motion, (pp. 281-290). Paris.

Stephens, J., Carson, J., Hult, D., & Bisom, D.
—2003. “Preservation of infrastructure by using weigh-in-motion coordinated weight enforcement,” Transportation Research Record: Journal of the Transportation Research Board, No. 1855, 143-150.

Strathman, J.
—2001. Economics of Overloading and the Effect of Weight Enforcement: Research Note. Portland, OR: Center for Urban Studies, College of Urban and Public Affairs.

Strathman, J., & Theisen, G.
—2002. Weight Enforcement and Evasion: Oregon Case Study. Portland, OR: Portland State University.

Straus, S., & Semmens, J.
—2006. Estimating the Cost of Overweight Vehicle Travel on Arizona Highways. Phoenix, AZ: Arizona Department of Transportation.

Taylor, B., Bergan, A., Lindgren, N., & Berthelot, C.
—2000. “The importance of commercial vehicle weight enforcement in safety and road asset management,” Traffic Technology International Annual Review, pp. 234-237. January.

Taylor, P.
—2002. “The role of transport inspectors.” Achieving Compliance through Strategic Enforcement, (pp. 131-137). Gold Coast, Australia.

Thomas, J.
—2002. “Requirements for effective enforcement.” Achieving Compliance through Strategic Enforcement, (pp. 125-129). Gold Coast, Australia.

Transport Topics
—2013. “Drivewyze, Norpass Partner in Agreement to Expand Mobile Weigh Station Bypasses.” Transport Topics. Arlington, VA: August 5.

Transportation Research Board.
—2002. Regulation of Weights, Lengths, and Widths of Commercial Motor Vehicles. Washington,

D.C.: Transportation Research Board.
—1990. Truck Weight Limits: Issues and Options. Washington, D.C.: Transportation Research Board, National Research Council.

United States Department of Transportation.
—2000. Comprehensive Truck Size and Weight Study. Washington, D.C.: United States Department of Transportation.

URS.
—2013. Indiana Truck Weight Compliance Business Plan. Unpublished: Indiana Department of Transportation, Indiana State Police, and Indiana Department of Revenue.
—2005. Minnesota Statewide Commercial Vehicle Weight Compliance Strategic Plan. Minneapolis, MN: Minnesota Department of Transportation.

Walker, C.
—2010. “Pushing the policy boundaries: Regulatory accreditation schemes, policy flexibility, and options for delivering a two-track regulatory system for the heavy vehicle sector.” 11th International Symposium on Heavy Vehicle Transport Technology. Melbourne, Australia: International Federation of Road Transport Technology.

Woodrooffe, J., Sweatman, P., Middleton, D., James, R., & Billing, J.R.
—2010. Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles. Washington, D.C.: National Cooperative Highway Research Program.

previous | next