Office of Operations Freight Management and Operations
Table of Contents

6.0 Conclusions

6.1 Summary of Improvements

As previously noted, virtual weigh stations have the potential to:

  • Improve operational efficiency and effectiveness of states’ roadside enforcement programs by targeting resources at commercial vehicles that are known to be overweight, are known to be operated by carriers with histories of poor safety performance and/or compliance with Federal and State size and weight regulations, or are currently noncompliant with Federal and/or State credentialing regulations;
  • Expand the geographic scope of a State’s roadside enforcement program to limit the number of roads on which a noncompliant commercial vehicle can operate without being detected by an enforcement resource;
  • Improve motor carrier compliance with Federal and State truck size and weight regulations;
  • Improve motor carrier safety through improved enforcement and a reduction in the number of operating overweight commercial vehicles;
  • Improve productivity of compliant motor carriers through a reduction in the number of roadside inspections to which they are subjected;
  • Provide an additional source of tracking information for motor carriers;
  • Reduce fuel consumption by legally loaded and operating carriers caused by unnecessary delays at weigh stations;
  • Reduce costs associated with new roadside enforcement assets due to the cost differential between deployment of a VWS and a fixed weigh station;
  • Improve real-time data sharing with commercial vehicles;
  • Provide a rich source of weather and traffic information for system managers; and
  • Provide augmented data sources for use by freight and highway planners.

6.2 Disadvantages and Limitations

While there currently are no known disadvantages to the deployment of VWS technology, the current state of technology does limit the applications that can be supported by these systems.  These limitations include:

  • Universal identification of commercial vehicles currently is not possible—The only identifiers that currently are common to all commercial vehicles are license plates, vehicle identification numbers, and USDOT numbers (for interstate motor carriers, as well as intrastate motor carriers in states participating in the PRISM program).  Unfortunately, these devices were designed to be read by a human and not by a machine/automated system.  License plate readers and USDOT number readers use a combination of cameras and OCR to interpret these visually-based identifiers into data that can be used as part an automated system.  The accuracy of the current LPR and USDOT reader technology varies widely due to operational and environmental factors and prohibits all commercial vehicles from being identified by VWS systems at this time.  Research is continuing to refine the camera hardware, as well as the OCR software, to improve the reliability of these systems but some states are concerned that optically-based VWS will never be able to achieve the goal of 100 percent identification.
  • Human interaction is still required—A variety of technical (e.g., accuracy of current WIM technology) and institutional/legal factors dictate that VWS technology serve only as a screening and planning tool for roadside enforcement personnel.  VWS deployments currently require that a human issue a citation for any overweight or compliance issue that may be detected.  As such, despite the presence of VWS technology a State’s enforcement capacity remains limited to the number of enforcement personnel that are on duty at one time in a given region.   These enforcement resources can be easily overwhelmed by the number of noncompliant vehicles operating in a region thereby reducing the overall utility and effectiveness of the technology.

6.3 Next Steps

In order to overcome the current technical/operational limitations affecting the effectiveness of VWS deployments, the following should be pursued:

  • Develop architecture for “e-Permitting/Virtual Weigh Stations”—With the complexity of the data model, business case, and overall use case associated with “e-Permitting/VWS,” schematics and diagrams are needed to identify and document data production and storage aspects supporting enforcement and truck support services at the roadside platform.  Data interrelationships can be identified, eliminating unnecessary duplication of information employed by the wide array of automated systems operating at the roadside.  Data flows enabling all Title 23 and Title 49 of the United States Code truck checks and measurements coupled with State permit verifications, revenue agency oversight interests, and truck company and driver services, need to be mapped in a comprehensive roadside architecture model providing insights that could enhance system performance and deliver Smart Roadside Initiative program objectives.
  • Determine which vehicle identification technology is best suited to identify all commercial vehicles—A variety of research is underway to determine the suitability of LPR, USDOT number readers, 900 MHz transponders, passive transponders, 5.9 GHz radios, cellular, and satellite technologies to achieve the goal of identifying 100 percent of commercial vehicles in real-time at highway speeds.  Each of these technologies has unique strengths and weaknesses.  For instance, while license plate readers currently do not offer 100 percent accuracy, they are based on an identifier (license plate) that is required on all commercial vehicles and for which there is an existing process of distribution and renewal (i.e., the registration process).  Conversely, passive transponders, while offering 100 percent accuracy in identification, currently do not have a process by which they can be distributed.  The FHWA universal truck identification project is designed to consider these operational and implementation issues and provide greater clarity regarding which technology offers the greatest potential to accurately identify all commercial vehicles at the roadside within three to five years.  The benefits/costs associated with mandating a technology also will be evaluated.
  • Conclusively document the benefits of VWS—The benefit data associated with VWS deployments currently is derived from evaluations of related systems/programs (e.g., electronic screening, CVISN).  In order to encourage future deployments of VWS and ensure that deployments are delivering their intended benefits, FHWA should commission a formal evaluation of the VWS concepts.  To the extent possible, the evaluation should isolate the relative benefits and costs associated with basic and expanded VWS components so that states can determine which VWS elements they want to deploy.
  • Investigate the deployment of direct enforcement concepts in the United States—The real compliance, safety, and operational benefits of VWS will be seen if the United States is able to move towards a direct enforcement regime using advanced technology.  Several countries in Europe currently employ direct enforcement based on the data from their WIM scales.  Similarly, some jurisdictions in the United States use direct/photo enforcement for red-light running and driving through an automated toll lane without a transponder.  An alternative to the current VWS model would include a gross vehicle and axle or axle set weight detection system capable of determining vehicle and axle weights with enough accuracy to enable the issuance of citations for violations.  Further, research into the institutional and legal implications associated with issuing citations and/or warnings based on an automated system also should be studied.  Precedents and lessons learned from other direct enforcement applications (e.g., red-light running cameras) should be a key part of this research.

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