Comprehensive Truck Size and Weight Limits Study: Comparison of Results Report

Chapter 3: Compliance Comparative Analysis

3.1 Purpose

The purpose of this section is to compare principal results of the Compliance Comparative Analysis (Task V.D) with other similar studies available in the literature. This involves two main objectives. First, those documents summarized in the revised desk scan that contain quantitative results pertaining directly to enforcement costs and effectiveness (i.e., the main objectives of the 2014 CTSW Study) are identified. Second, the results from each of the selected documents are reviewed and objectively compared with the results of the 2014 CTSW Study. Two types of comparisons are provided: (1) those pertaining to the scenario results; and (2) other CTSW Study results.

3.2 Comparison of Compliance Analysis Results

The Compliance Comparative Analysis (Task V.D) estimates impacts on the costs and effectiveness of truck size and weight (TSW) enforcement for the six 2014 CTSW Study scenarios. Table 3-1 summarizes the scenario results. The cost comparisons examine changes in personnel costs for each of the six scenarios. The analysis reveals decreases in personnel costs for all six scenarios relative to the base case personnel costs, ranging in magnitude from 0.3 percent (Scenario 1) to 1.1 percent (Scenario 4). The effectiveness comparisons are based on estimated changes in the proportion of underweight vehicle-miles-traveled (VMT) by control vehicles and alternative configurations for four of the six scenarios.

Table 3-1: Summary of Scenario Results for the Compliance Comparative Analysis.
Scenario	Change in Enforcement Personnel Costs Relative to Base Case [%]	Expected Impact on Enforcement Effectiveness
1. 3-S2 @ 88K lb. (53')	-0.3	Not analyzed
2. 3-S3 @ 91K lb. (53')	-0.4	Limited impact
3. 3-S3 @ 97K lb. (53')	-1.0	Limited or no impact
4. 2-S1-2 @ 80 K lb. (2 x 33')	-1.1	Not analyzed
5. 2-S1-2-2 @ 105.5K lb. (3 x 28.5')	-0.7	Limited impact
6. 3-S2-2-2 @ 129K lb. (3 x 28.5')	-0.7	Limited impact

Unlike the other task areas of the 2014 CTSW Study, there are no other studies available with which to compare the results of the enforcement costs and effectiveness scenario analyses. The previous USDOT 2000 CTSW Study discussed aspects of TSW enforcement programs, but the scenario analysis applied in that study excluded enforcement costs or effectiveness. This is also true for the follow-on USDOT, Western Uniformity Scenario Analysis. However, this second study appears to recognize this shortcoming by specifically stating that "there is no detailed discussion of regulatory, enforcement, or other implementation issues that would have to be considered before an option such as the Western Uniformity Scenario Study could be implemented" (USDOT 2004, p. I-1).

Two recent regional TSW studies conducted by Cambridge Systematics for Minnesota (2006) and Wisconsin (2009) also exclude enforcement costs and effectiveness from their scenario analyses. Thus, direct comparisons between the results of the 2014 CTSW Study and these analyses are not possible.

3.3 Comparison of Other Results

Despite a lack of directly comparable scenario-based studies in the literature, some of the 2014 CTSW Study's results can be generally compared with those reported in the literature. Table 3-2 provides these comparisons. In many cases, direct comparisons are difficult due to differences in the approaches and objectives of comparable studies; these differences are briefly noted in the table, but a detailed review and interpretation of the other studies is not included.

Table 3-2 compares measures of the cost and effectiveness of TSW enforcement programs nationwide, referencing results provided in the previous 2000 CTSW Study. Specifically, comparisons are made of the following measures: expenditures on TSW enforcement programs, total nationwide weighings, total nationwide non-weigh-in-motion (WIM) weighings, total nationwide load-shifting and offloading vehicles, nationwide citation rates, and average nationwide cost per non-WIM weighing. These comparisons offer longitudinal (i.e., time series) insights about TSW enforcement program costs, activities, and effectiveness.

Table 3-2 also compares enforcement program effectiveness-measured in the 2014 CTSW Study using WIM data collected at various locations for the control vehicles and alternative configurations-with estimates of overweight trucking that have been reported in the literature using a variety of estimation methods and data sources. Though direct comparisons are not possible, in general, the range of results determined in the 2014 CTSW Study agrees with the range of results reported in the literature.

Table 3-2: Comparison of Results.
Current 2014 CTSW Study's Result	Comparable Result
Total nationwide expenditures on TSW enforcement reported by states range from $432 million to $487 million (in 2011 USD)	Total nationwide expenditures on truck weight enforcement reported by states in 1995 was approximately $414 million (in 2011 USD¹) (USDOT 2000)
Total nationwide weighings in 44 reporting states range from approximately 177 million to approximately 196 million between 2008 and 2012	Total nationwide weighings reported by states ranged from approximately 105 million to approximately 170 million between 1985 and 1995 (USDOT 2000)
Total nationwide non-WIM weighings (i.e., fixed platform, portable, semi-portable) in 44 reporting states range from approximately 65 million to approximately 80 million between 2008 and 2012	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 (USDOT 2000)
Total nationwide load-shifting and offloading vehicles reported by states range from approximately 275,000 to approximately 383,000 between 2008 and 2012	Total nationwide load-shifting and offloading vehicles reported by states ranged from approximately 478,000 to approximately 579,000 between 1985 and 1995 (USDOT 2000)
Nationwide citation rates (weight citations per non-WIM weighing) range from 0.013 in 2008 to 0.010 in 2012	Nationwide citation rates (weight citations per non-WIM weighing) ranged from 0.007 in 1985 to 0.006 in 1995 (USDOT 2000)
Average nationwide cost per non-WIM weighing ranges from $6 to $8 between 2008 and 2012 (in 2011 USD)	Average nationwide cost per non-WIM weighing was approximately $4 in 1995 (in 2011 USD¹) (USDOT 2000)
Proportion of underweight tandem axle weight observations at WIM sites ranges from 87 to 97 percent, depending on configuration and location	15 percent of large trucks would exceed axle weight limits on a segment of interstate highway where enforcement was not taking place (Grenzeback et al. 1988) 12 percent of tandem axles exceed the federal limit, based on WIM data (Hajek and Selsneva 2000) 13 percent of tandem axles exceed the weight limit in Vermont (FHWA 2012) 99 percent of single, tandem, and tridem axle weights for Rocky Mountain doubles and Turnpike doubles comply with static weight limits, based on WIM data collected in the Canadian Prairie Region (Regehr et al., 2010) 15 percent of trucks weighed at fixed weigh scales on interstate highways violate weight laws (Carson 2011) 30 percent of trucks on scale by-pass routes violate weight laws (Carson 2011)
Proportion of underweight gross vehicle weight observations at WIM sites ranges from 73 to 100 percent, depending on configuration and location	15 percent of large trucks would exceed gross vehicle weight limits on a segment of interstate highway where enforcement was not taking place (Grenzeback et al. 1988) A minimum violation rate of 6 percent exists at fixed weigh scales (Grenzeback et al., 1988) 10 to 20 percent of all combinations are operating overweight without a permit, based on WIM data (TRB 1990) 10 to 25 percent of trucks are overloaded, according to enforcement personnel (TRB 1990) 0.6 percent of trucks exceed gross vehicle weight limits at weigh stations (FHWA 1993) 10 percent of all miles of travel by trucks with three or more axles is attributed to vehicles weighing more than 80,000 lbs. (U.S. DOT, unpublished) 1 percent of trucks weighed at continuously operated weigh scales violate weight laws (Taylor et al. 2000) 12 to 34 percent of trucks weighed at low enforcement level weigh scales (no definition for "low" provided) violate weight laws (Taylor et al. 2000) The number of overweight vehicles ranged from 2.27 to 3.19 percent on a weigh scale by-pass route under initial conditions, during scale closure, and after scale re-opening, based on WIM data (Strathman and Theisen 2002) Based on a survey of states, between 0.5 and 30 percent of truck travel is overweight in surveyed states (Straus and Semmens 2006) Based on a survey of states: 5 of 12 responding states report that less than 5 percent of trucks weighed at weigh stations are overloaded, 3 of 12 responding states report overloaded rates at weigh stations between 5 and 10 percent, 2 of 12 responding states report overloaded rates at weigh stations between 10 and 15 percent, and 2 of 12 responding states report overloaded rates at weigh stations between 20 and 25 percent (Ramseyer et al. 2008) 99 percent of Rocky Mountain doubles and Turnpike doubles comply with static GVW limit, based on WIM data in the Canadian Prairie Region (Regehr et al. 2010) 15 percent of trucks weighed at fixed weigh scales on interstate highways violate weight laws (Carson 2011) 30 percent of trucks on scale by-pass routes violate weight laws (Carson 2011)

¹Costs are normalized to 2011 USD using the Consumer Price Index published by the Bureau of Labor Statistics.

3.4 References

Cambridge Systematics.

-2009. 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.

Federal Highway Administration.

-2012. Vermont Pilot Program Report. Washington, D.C.: Federal Highway Administration.

-1993. Overweight Vehicles - Permits and Penalties. Washington, D.C.: Federal Highway Administration.

Grenzeback, L., Stowers, J., & Boghani, A.

-1988. Feasibility of a National Heavy-Vehicle Monitoring System. Washington, D.C.: Transportation Research Board, National Research Council.

Hajek, J., & Selsneva, O.

-2000. Estimating Cumulative Traffic Loads, Final Report for Phase 1. Washington, D.C.: Federal Highway Administration.

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.

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.

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.

-2004. Western Uniformity Scenario Analysis: A Regional Truck Size and Weight Scenario Requested by the Western Governors' Association. Washington, D.C.: United States Department of Transportation.

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