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Federal Highway Administration > Publications > Public Roads > Vol. 72 · No. 6 > Exploring Vehicle Size And Weight Solutions

May/Jun 2009
Vol. 72 · No. 6

Publication Number: FHWA-HRT-09-004

Exploring Vehicle Size And Weight Solutions

by Jodi Carson and Tom Kearney

A scan tour in Europe demonstrated a number of innovative strategies for enforcing commercial motor VSW regulations.

In the Netherlands, the U.S. scan team inspected this $1.2 million weigh-in-motion calibration vehicle, which eliminates traditional dynamic-to-static measurement adjustments and the associated loss in accuracy.
In the Netherlands, the U.S. scan team inspected this $1.2 million weigh-in-motion calibration vehicle, which eliminates traditional dynamic-to-static measurement adjustments and the associated loss in accuracy.

Commercial motor vehicle size and weight (VSW) requirements are in place for roadway safety and infrastructure preservation. However, the amount of infrastructure damage an overweight vehicle causes is geometrically larger than the weight increase; for example, an increase in axle weight from 18,000 pounds to 20,000 pounds causes 50 percent more damage to the pavement. Given the capital investment currently spent to maintain existing infrastructure — 88 percent of the total amount of Federal-Aid Highway Program funds in 2007 were obligated for restoration and rehabilitation, resurfacing, and reconstruction — it is critical that adequate size and weight enforcement be in place.

Even as the transportation community needs to maximize the service life of existing assets, the volume of freight moving on the Nation's highway system continues to grow, reflecting the increasing population and demand for goods. Transportation professionals must find a way to accommodate this growth while preserving infrastructure. Legal loads must be allowed to move unencumbered throughout the system to improve the efficiency and productivity of truck carriers, and illegal loads must be caught and penalized. The challenge is increasing the use of technology and forward-thinking practices and procedures to intelligently target enforcement activities to ensure safety, preserve the Nation's infrastructure investment, and improve truck productivity.

To improve the efficiency and effectiveness of VSW enforcement in the United States, the Federal Highway Administration (FHWA), American Association of State Highway and Transportation Officials (AASHTO), and National Cooperative Highway Research Program (NCHRP) conducted an international scan tour in 2006 to six European countries that are using innovative practices, procedures, and technologies to enforce VSW. "The scan reviewed and evaluated contemporary European procedures and technologies for enforcing commercial motor vehicle size and weight laws and regulations," says Jeff G. Honefanger, cochair of the scan tour and manager of the Ohio Department of Transportation (ODOT) Special Hauling Permits Section.

Based on the scan team's observations, the near-term activities to support U.S. implementation include a pilot installation of a bridge weigh-in-motion (WIM) system on a representative structure, a demonstration of the European mobile enforcement approach to prescreening suspected overweight vehicles, a case study describing the effective use of WIM data, and a synthesis of existing research on linkages between overweight commercial motor vehicles and roadway safety. Additional strategies intended for investigation for potential U.S. implementation include a heavy goods vehicle control facility modeled after facilities observed in Switzerland, the use of WIM systems for direct enforcement, and behavior-based enforcement activities that target habitually noncompliant carriers.

The Study's Locales, Participants, and Focus

Using information obtained from published literature, various Internet sites, reports on previous scanning studies related to the subject, and U.S. and European experts in the field, the scan team selected the following locales for the study: France, Germany, the Netherlands, Slovenia, and Switzerland. In addition to visiting these countries, the scan team met with members of the European Union (EU) in Brussels, Belgium, to gain perspective on efforts to harmonize VSW enforcement activities among EU countries.

A team of U.S. experts in commercial motor VSW enforcement conducted the scan study. The 10-member team included three members from FHWA, five from State departments of transportation (DOTs), one from law enforcement, and one from academia. One of the members from FHWA and one from the Ohio Department of Transportation, representing AASHTO, led the team. In addition to breadth in agency types, the scan team had varied expertise in VSW technologies, procedures, data applications, public-private involvement, and harmonization.

The scan study considered five specific aspects of European VSW enforcement:

  • Emerging VSW enforcement technologies, including third- generation WIM systems that can produce reliable evidence of specific violations capable of withstanding legal challenge
  • Unconventional VSW enforcement procedures, including alternative performance-based programs
  • Novel uses or applications of WIM data to support pavement design, bridge and structural design, traffic engineering, transportation planning, and ongoing performance monitoring and evaluation of VSW enforcement programs
  • Innovative public-private funding mechanisms for VSW enforcement technologies and programs
  • Multinational programs to harmonize administrative and operational VSW enforcement among member countries

Concurrently, the scan team considered intrinsic benefits related to infrastructure preservation, enforcement efficiency and effectiveness, commercial motor vehicle productivity, emissions, safety, and data quantity and quality. Complete documentation of the scanning study, Commercial Motor Vehicle Size and Weight Enforcement in Europe (FHWA-PL-07-002), is available electronically through the FHWA Office of International Programs (OIP) (see below).

Enforcement Technologies

Two of the six countries visited, Switzerland and Germany, use technology to support enforcement of commercial motor vehicle size regulations. To permit direct enforcement, the Swiss use an automated vehicle profiler system in low-speed applications of less than 6 miles per hour, mi/h (10 kilometers per hour, km/h). The gantry-mounted system, installed at off-route stationary enforcement locations, uses laser scan technology to provide a full three-dimensional (3-D) profile, including the height, width, and length of a vehicle. Two laser scanners mounted on a gantry capture the height and width measurements, and a third scanner mounted on another gantry captures the length. As a vehicle passes under the gantries, accompanying software creates a 3-D model that can be rotated in any direction for analysis. This system provides a more complete and accurate 3-D picture of a vehicle than is provided by conventional manual methods using a measuring tape or bar, and allows enforcement officials to focus on other aspects of inspection.

Cover of Commercial Vehicle Size and Weight Enforcement in Europe

For high-speed applications, the Germans use the same gantry- mounted vehicle profiler system, installed along 7,456 miles (12,000 kilometers) of German autobahn as part of its larger toll collection system, to preselect potentially oversized vehicles from the traffic stream.

Shown here are strain gauge and data hub instrumentation for bridge WIM technology on the underside of a concrete bridge deck near Ljubljana, Slovenia.
Shown here are strain gauge and data hub instrumentation for bridge WIM technology on the underside of a concrete bridge deck near Ljubljana, Slovenia.

To support enforcement of commercial motor vehicle weight regulations, Slovenia is using a bridge WIM system successfully and extensively for a variety of applications, including preselection for mobile enforcement; remote field verification of permitted overweight vehicles; alternate route monitoring for possible bypass by noncompliant vehicles; and data support for planning, design, and structural analysis. Bridge WIM systems use strain transducers or gauges attached to the bridge soffit or embedded in the bridge deck, plus onroad axle detectors or Nothing-On-the-Road/Free-of-Axle Detector (NORFAD) systems to provide information on axle and gross weights, axle spacing, speed, and position for commercial motor vehicles and other vehicles traveling at highway speeds. To date, the Slovenian bridge WIM system has proven most successful on short, stiff structures with integral concrete slabs.

France is testing WIM systems on a variety of bridge types, generating interest among some of the other countries visited during the scan tour. In addition, the Netherlands recently installed a bridge WIM system for testing on Dutch highways and now is identifying other bridges for potential implementation.

The scan team also observed conventional inroad WIM systems to be used widely, although the extent of technology implementation varied by country. By developing a European WIM system specification (called the COST 323 specification), the EU encouraged consistency in the selection of technology deployment sites and determination of measurement accuracy. The scan team also noted a general consistency in the use of low-cost WIM sensors such as piezoquartz or piezoceramic sensors, which estimate dynamic vehicle loads based on the proportional voltage differential that results when a vehicle passes over and compresses the sensor. Purported differences relate to sensor durability and sensitivity to temperature, among other factors.

Shortcomings that have been historically observed related to WIM system accuracy and maintenance have been largely accommodated in the countries visited during the scan. Novel WIM system calibration technologies and procedures help to ensure system accuracy while minimizing maintenance costs. The Netherlands has developed a dynamic calibration vehicle that eliminates traditional dynamic-to-static measurement adjustments and the associated loss in accuracy. France and the Netherlands use continuous, ongoing calibration procedures to ensure an adequate level of WIM system performance. Static axle weight records obtained during scheduled enforcement activities are directly compared for accuracy to the axle weight records captured by the WIM system for the same vehicles in near real time. If an unacceptable level of data error is observed, the problem is corrected quickly through system calibration or other remedial action.

In general, the accuracy attained by WIM systems is sufficient to support a variety of strategies intended to enhance the efficiency and effectiveness of enforcement and to provide data to support infrastructure planning and design, but it is insufficient for direct, automated enforcement (that is, issuing citations based solely on WIM measurements without the need for subsequent static measurements).

France and the Netherlands cooperatively are investigating multiple-sensor WIM technology to achieve sufficient accuracy levels to support direct enforcement of commercial vehicle weight limits in high-speed applications but estimate this application to be 5 to 20 years in the future. Primary challenges include attaining sufficient accuracy levels for the WIM systems — that is, accuracy class A(5) in the COST 323 European specification; gaining certification approval from the national metrological bodies; and modifying existing laws that require static weight measurements.

Portable static scales are weighing this truck at a mobile enforcement site in Slovenia.
Portable static scales are weighing this truck at a mobile enforcement site in Slovenia.

As an interim step, France recently obtained certification approval of low-speed WIM systems for direct enforcement applications from the National Metrology Institute, allowing for an estimated tenfold increase in the number of vehicles processed. The United Kingdom and Germany are already using low-speed WIM for direct enforcement, although the team did not observe this application during the scan tour.

Enforcement Procedures

In several of the countries visited, the scan team observed a high level of collaboration in VSW enforcement among similar agencies of different jurisdictional levels (that is, national and regional law enforcement agencies) and among different agencies (such as transportation and law enforcement). In addition, private sector entities work closely with government and research bodies to refine and enhance product performance and accuracy.

This Haenni scale mounted in the pavement surface at a mobile enforcement site in Slovenia is measuring truck axle weight.
This Haenni scale mounted in the pavement surface at a mobile enforcement site in Slovenia is measuring truck axle weight.

The scan team consistently observed a greater use of mobile enforcement and fewer fixed roadside weigh facilities in Europe than in the United States. The European strategy results in a lower volume of trucks being processed and is challenged by limited roadside infrastructure to support vehicle inspection and offloading. Nonetheless, this approach provides greater flexibility to respond to dynamic industry loading and routing patterns, and results in higher violation capture rates (that is, the number of citations issued compared to the number of vehicles inspected) and a subsequent increase in enforcement efficiency and effectiveness.

Video technology often is used in conjunction with WIM systems to support the real-time preselection of potentially noncompliant vehicles during mobile enforcement activities. Also, it is used for the scheduling and dispatch of enforcement resources based on historic weight violation patterns, and the identification of habitually noncompliant carriers for advisory notices and preventive carrier visits.

This combination of technologies also is used to support the real-time remote verification of permitted oversize/overweight (OS/OW) vehicle movements. Additional innovative procedures for addressing OS/OW permitting in the countries visited include the development and provision of Web sites allowing truck drivers to self-route based on origin, destination, and route restrictions (Switzerland) and the use of calibrated influence lines to calculate the safety of a bridge using the exact axle loadings and spacing of candidate overweight vehicle loads (France, Slovenia). Influence lines are mathematical expressions in graphical form derived from bridge WIM systems that describe the structure's response to a load anywhere along the structure.

In many of the countries visited, the potential bypass of enforcement activities by noncompliant vehicles was raised as a concern. The use of mobile enforcement procedures and low-cost technologies better positions European enforcement officials to address bypass challenges. France and the Netherlands have integrated bypass considerations into their WIM system site selection process. The Netherlands also has integrated bypass considerations into site-level system plans. On multilane facilities, WIM sensors are installed in the right two lanes; remaining lanes are equipped only with electronic loops and overhead cameras to detect bypassing vehicles. As designed, overall system costs are reduced without significantly altering the effectiveness of enforcement efforts.

Benefits from these technologies or procedures have not been extensively quantified. Swiss, Dutch, and French representatives reported general benefits related to increased enforcement efficiency through the use of technology (that is, providing greater enforcement effort with fewer human resources). The most common quantified benefit they reported related to onsite enforcement efficiency — the number of citations or warnings issued compared to the number of vehicles inspected.

Unique Data Applications

The European countries visited use WIM system data most often for supporting various enforcement-related strategies, including the preselection of potentially noncompliant vehicles during mobile enforcement operations, the scheduling and dispatch of enforcement resources based on historical weight violation patterns, and the identification of habitually noncompliant carriers for advisory notices and preventive carrier visits. Use of this data to support planning, historical trend analysis, policy and pricing decisions, design, structure analysis, and permitting is more limited. Information on "loadings" on the roadway networks continues to increase in its value and use for these purposes. In the United States, several States currently operate and a few others are exploring the construction of enterprise-level WIM database systems allowing multiple user access to vehicle weight data for the purposes mentioned. This type of data system offering weight data to a wide variety of customers was a common feature of the WIM programs operated by each of the six countries visited by the scan team.

This screenshot shows the software interface used to support real-time mobile enforcement activities in the Netherlands.
This screenshot shows the software interface used to support real-time mobile enforcement activities in the Netherlands.

Data quality was reported to be largely sufficient for each of these various applications. The most common shortcoming noted was the extent of geographic coverage.

Public-Private Funding

In Europe, investment in VSW enforcement often is justified through environmental impacts, road safety considerations, and infrastructure impacts. The development of enforcement approaches, tools, and techniques is driven also by a desire to maintain fair competition within the trucking industry. In the United States, primary motivators include infrastructure preservation and safety, although the basis for safety benefits is not well quantified.

Several of the countries visited use some form of tolling or pricing to help finance roadway operations, maintenance, and improvements, with a separate focus on the movement of heavy goods. The extent and nature of tolling systems varies from country to country, but often includes public-private operation of systems and weight- or size-based tolls for heavy vehicle movements. None of the tolling schedules observed during the scan tour is based on actual or real-time weights. More often, toll schedules reflect a fixed, registered weight capacity and do not distinguish between fully loaded or empty transports. This latter procedure encourages the trucking industry to operate more efficiently to avoid paying tolls for empty transports.

Similarly, the fee structure for special permits is not always based on actual or real-time weights, but instead reflects a flat-fee structure.

Emerging user fees are being investigated and developed as part of the European Eureka Logchain Footprint project. Eight EU countries are participating in the project, which aims to support development of a pan-European heavy goods vehicle surcharge, with its value determined by the unique environmental effects (noise, vibration, emissions) of a particular vehicle.

A toll collection official is showing an onboard information technology system used to help enforce Germany's automated truck tolling program.
A toll collection official is showing an onboard information technology system used to help enforce Germany's automated truck tolling program.

The team noted that both industry and government are sensitive toward ensuring fair competition among trucking companies. Industry is largely supportive of enforcement approaches, tools, and techniques that will help ensure fair competition. The scan team observed that, despite this industry support, direct participation by the trucking industry to address VSW enforcement challenges is minimal. The Netherlands actively sought solutions from the industry for VSW enforcement without any initial actionable feedback. Over time, the Dutch trucking industry responded to enhanced VSW enforcement effectiveness by modifying loading behavior, enhancing self-monitoring capabilities, or adding additional axles onto new or existing vehicles to reduce per axle loads and increase compliance.

Harmonization Approaches

A common goal or priority in decisionmaking for the countries visited is creating consistency within the EU while maintaining the economic interests of individual countries.

In general, EU member countries exhibit a very high level of coordination in undertaking research. The Forum of European National Highway Research Laboratories and the EU provide the framework for administering large-scale, multiyear, coordinated research. A demonstrated outcome from such coordinated research is the COST 323 European specification for WIM systems, which has provided a common and widely accepted prestandard that all parties have used since its establishment in the late 1990s.

Scan team members watch a Slovenian enforcement official operate roadside bridge WIM software on a laptop.
Scan team members watch a Slovenian enforcement official operate roadside bridge WIM software on a laptop.

The European Traffic Police Network provides a framework for multinational, coordinated highway enforcement. It was interesting to note the similarity in venues for coordination among enforcement officials — the European Traffic Police Network in Europe and the Commercial Vehicle Safety Alliance in North America — and collaborative highway research endeavors — NCHRP and the Transportation Research Board in the United States and the Forum of European National Highway Research Laboratories in Europe — considering the issue of sovereignty across European nations.

Implementation Recommendations And Outcomes

Based on these general findings and observations, the scan team ranked an expansive preliminary list of European commercial motor VSW enforcement technologies and procedures identified as part of the scan. The scan team members subsequently consented to the exercise of ranking as high, medium, or low interest levels for implementation in the United States. By adopting these rankings, the team was able to identify high-priority technologies or procedures for implementation — those implementation priorities assigned the greatest potential for technology transfer and enhancements to current U.S. tools and practices for enforcing truck size and weight limits.

Several implementation opportunities, by their scope and context, were determined to overlap or, upon retrospection, appear redundant. By combining some opportunities because of perceived overlap, the scan tour implementation team (STIT) was able to focus the high-priority opportunities into seven specific areas of technology and procedure:

  • Slovenia's Bridge WIM (B-WIM) System (France, Slovenia)
  • Swiss heavy goods vehicle control facility operations and elements (Switzerland)
  • Effective prescreening, using automated tools, to support mobile enforcement (France, the Netherlands, Slovenia, Switzerland)
  • WIM for direct enforcement: a template for implementation and certification (France)
  • Behavior-based enforcement activities (France, the Netherlands)
  • Synthesis of the safety implications of OS/OW commercial vehicles (Belgium)
  • WIM data used effectively: Dutch case study (the Netherlands)

The STIT also identified specific strategies for advancing these implementation opportunities, with various scan team members assigned supporting action items. The following sections discuss details of these implementation opportunities and outcomes to date.

Slovenia Bridge WIM System

A partnership between research staff at the Slovenian National Building and Civil Engineering Institute's research department and a private engineering firm, Centro Español de Servicios Telemáticos, S.A., resulted in the development of the SiWIMTM bridge WIM system in Slovenia.

The SiWIM system captures axle weights, gross vehicle weights (GVW), axle spacing, vehicle speed, and vehicle class. Extensive research centered on the behavior of the influence line that describes the structure's response to a load anywhere along the structure when loading is applied to a bridge deck led to the ability to estimate a vehicle's static weight within acceptable levels of accuracy. The Slovenian SiWIM has proven most successful on short-deck orthotropic bridges of 16 to 33 feet (5 to 10 meters) long.

An attractive feature of this technology is that measurement telemetry is installed on the underside of the bridge deck, eliminating the need to cut into pavement structures as is typically the case. The drawback of the Slovenian B-WIM tool is that there are limited opportunities for use based upon the size of bridge structures that accurate readings can be gained from. Research is underway currently to develop methods that would expand the population of bridge types and sizes where B-WIM could estimate effectively the static weight of commercial motor vehicles traveling at normal highway speeds.

System instrumentation can be fully applied to an underdeck location, eliminating the need to disrupt traffic during installation. The time required for installation is not significant and, once bridges are initially instrumented, the strain transducers or gauges can be easily moved among bridges, making the system highly portable. In Slovenia, five SiWIM devices are used to collect data for 1 week at 30 locations twice per year.

Swiss mobile enforcement officers are processing trucks for size and weight compliance at a heavy goods vehicle control center.
Swiss mobile enforcement officers are processing trucks for size and weight compliance at a heavy goods vehicle control center.

By eliminating the need to disrupt traffic and minimizing worker risk during installation, B-WIM systems offer major benefits over current U.S. practices. In addition, U.S. applications of B-WIM systems could enhance a broad range of capabilities for commercial motor vehicle weight enforcement and provide important information for bridge management systems. A single test site is currently under development in Alabama, with the longer term intent of deploying and evaluating B-WIM systems in additional States through a pooled fund or other approach.

Swiss Heavy Goods Control Facility

To protect highway tunnel facilities and roadway infrastructure from the impacts of OS/OW vehicles, Switzerland developed and implemented an efficient and effective approach to simultaneously capture size measurements and weight measurements at stationary enforcement locations. High-speed WIM and video systems are used in conjunction with these facilities to preselect suspected noncompliant vehicles for further inspection. Once inside the facility, vehicles are directed to drive under the gantries at low speeds so that accompanying software can create 3-D models of the vehicles and then onto a static weigh bridge that provides simultaneous axle and gross vehicle weight measurements.

An attractive element of the Swiss heavy goods vehicle control facility is the user-friendly presentation of size and weight data to the enforcement officers. A horizontal line depicts legal axle and GVW allowances; captured weight measurements that exceed legal limits are readily apparent. Similarly, captured size measurements that exceed legal height, width, or length allowances are depicted in red on the 3-D model. The system automatically generates size- and weight-related citations for issuance to the vehicle operator and submission to the courts.

Swiss enforcement personnel reported the ability to obtain more accurate measurements with less manpower, resulting in more effective and efficient enforcement. The Swiss currently operate three control centers with additional centers in the planning and development stages.

In February 2008, Swiss officials visited the United States to exchange information on technology-based approaches for commercial motor VSW enforcement. Participants included Swiss transportation and law enforcement officials and their U.S. counterparts at the Federal and State levels. During the visit, the Swiss representatives provided an overview of VSW management policies and procedures in Switzerland and a description of their heavy goods vehicle control sites. The scan team has not yet identified model deployment sites in the United States; however, the team believes that enforcement stations at key high-volume domestic or international land crossings might be beneficial.

Prescreening for Mobile Enforcement

"A significant level of interest exists in the United States in the use of automation tools and technology to improve commercial motor vehicle size and weight enforcement," says John Nicholas, transportation specialist in FHWA's Office of Freight Management and Operations and former commercial vehicle program manager at Washington State Patrol.

The scan team observed mobile enforcement activities in four of the six countries visited: France, the Netherlands, Slovenia, and Switzerland. In each case, high-speed WIM technology provides for mainline prescreening of suspected overweight commercial motor vehicles. Overweight detections trigger video capture (that is, digital photo images) of the vehicles. The system transmits weight and image data via short-range communications to enforcement personnel, enabling them to identify appropriate commercial vehicles in the traffic stream and escort them off the mainline for further investigation.

U.S. States already employ mobile enforcement to varying degrees. The scan team identified a preliminary need to characterize the nature and extent of mobile enforcement in the United States before promoting European practices. Such a state-of-the-practice review has not yet been initiated.

WIM and Direct Enforcement: Template For Implementation And Certification

In many cases, institutional barriers challenge the widespread deployment of advanced technologies for VSW enforcement. The use of WIM systems for direct enforcement requires support from both the standards bodies charged with equipment certification and judicial bodies responsible for related legal actions. Enforcement officials can test and certify low-speed WIM systems using methods similar to those employed for static weighing equipment, making deployment of the systems a logical first step toward direct enforcement. The testing and certification process for high-speed WIM systems is more complex and requires the development of new acceptance methods.

At a mobile enforcement site in France, officials required offloading of this logging truck.
At a mobile enforcement site in France, officials required offloading of this logging truck.

French officials are leading efforts to overcome institutional challenges, focusing initially on the use of low-speed WIM systems for direct enforcement. The Dutch are focusing on gaining acceptance of high-speed WIM systems.

Because similar institutional challenges would be encountered in the United States, the scan team recommended an indepth review of the French and Dutch evolutionary process for acceptance of WIM systems for direct enforcement, with a concurrent review of the U.S. direct enforcement climate and requirements. No such review has yet begun.

Behavior-Based Enforcement Activities

Using high-speed WIM systems and video technology, Dutch and French officials employ historical data to identify habitually noncompliant carriers. This information is captured continuously (24 hours a day, 7 days a week), regardless of whether mobile enforcement is taking place.

Carriers with the highest historical overloading offenses are sent an initial advisory notice, enforcement officials meet at their place of business, and a monitoring period begins. If loading behavior sufficiently improves, the carrier is reclassified as compliant. If it does not, roadside enforcement personnel begin instituting graduated enforcement actions against the carrier. France is beginning a 3-year study to determine the effectiveness of this process.

In the United States, the Federal Motor Carrier Safety Administration uses a similar process when conducting safety inspections of carriers operating commercial vehicle fleets. The potential application of a process that includes commercial VSW violation patterns is in the early stages of discussion between FHWA and the Federal Motor Carrier Safety Administration.

Synthesis of Safety Implications of OS/OW Commercial Vehicles

In the United States, justification and authority for conducting VSW enforcement are vested in the public's interest in preserving infrastructure. The scan team observed the same principle in each of the countries visited.

In addition, several of the countries identified safety as a primary motivator for VSW enforcement. In Belgium, officials have linked weight enforcement to the public's interest in safe operating conditions on highways. After years of collecting and analyzing weight and speed data, Belgian officials noted direct relationships between excessive speed by overweight vehicles involved in highway crashes and the frequency of fatalities. As a result, they were able to build the case to legislative leaders that weight and speed need to be regulated aggressively.

"Although public concerns about the impact of overweight vehicles on bridge and pavement conditions and on equitable trade practices are valid, the safety benefits tied to commercial vehicle weight enforcement need to be better defined [in the United States]," says FHWA's Nicholas. To understand the relationship between commercial motor vehicle weight condition and safety, researchers at The University of Alabama are preparing a white paper evaluating the availability of adequate data to articulate the safety aspects of conducting truck size and weight enforcement activities. The researchers presented their preliminary findings in a paper titled "Safety Implications of Truck Size and Weight Activities" at the 2008 International Conference on Weigh-in-Motion (ICWIM05)/Heavy Vehicle and Truck Technologies (HVTT10) Conference in Paris, France.

Use of WIM Data: Dutch Case Study

"The breadth of application potential for WIM data has long been recognized by U.S. transportation agencies," says Ric Athey, assistant director of Enforcement Services in the Motor Vehicle Division of Arizona DOT. "Few, however, are utilizing WIM data to its full extent, frequently limiting its application to support pavement infrastructure design and commercial vehicle weight enforcement activities through prescreening."

Cover of Effective Use of Weigh-in-Motion Data: The Netherlands Case Study

The Dutch have developed a robust WIM data management system that currently supports a broad array of vehicle weight regulation and enforcement activities, as well as long-term planning and decisionmaking activities, plus the conduct of special studies. They have integrated extensive quality control and quality assurance protocols into this WIM data management system, significantly enhancing confidence in the vehicle information provided.

In the United States, officials at State DOTs operate databases to manage highway and bridge programs and monitor travel to support program and policy development. To assist DOTs in extracting greater value from the databases, FHWA and AASHTO, supporting implementation of the scan findings, contracted the Texas Transportation Institute to prepare an informational brochure that documents the Netherlands' use of WIM data to support VSW management. The Netherlands' efforts include issuance of weekly data quality reports to enhance data confidence and integration of WIM data into long-term, aggressive planning goals related to reducing the number of overweight vehicles on the road. The six-page brochure, "Effective Use of Weigh-in-Motion Data: The Netherlands Case Study" (FHWA-PL-07-028) is available electronically at http://international.fhwa.dot.gov /links/pub_details.cfm?id=556. OIP distributed the brochure to State-level traffic monitoring and VSW enforcement personnel to help support implementation.

Where Do We Go From Here?

Next steps include defining specific timeframes, funding requirements, and sources for investigation or implementation of the remaining high-priority strategies.

Several companion activities currently are underway. FHWA is conducting a study to identify the use of best-practice technologies for commercial motor VSW enforcement in the United States and to develop a conceptual phased implementation plan modeled after the LegoTM or building block approach observed in the Netherlands for enhancing enforcement efficiency through technology. Technical assistance and consultation has been solicited from European experts met during the scan in the area of truck enforcement technologies, adding value and insight into the development and conduct of this FHWA-sponsored study titled Truck Size and Weight Enforcement Technology, being prepared by Cambridge Systematics, Inc.

Another effort, sponsored by NCHRP, involves outreach to State DOT executive-level staff to increase their awareness and support of integration of various implementation opportunities into their State programs. Presentations of key scan findings were made at the 2008 AASHTO annual meeting held in Hartford, CT. Site visits to a limited number of individual States for more detailed presentations on program enhancement opportunities associated with implementing scan findings will be scheduled as part of this effort.

The scan implementation team currently is planning a national brainstorm session on the role of WIM technology in truck enforcement programs over the short, medium, and long terms. "Creating overarching national support for automated truck weight enforcement, as was repeatedly seen in each of the European nations visited, is critical to a sustainable, coordinated national enforcement program that would benefit all States," says Athey. "Articulating the benefits of automated enforcement is crucial to this support; the brainstorm session will focus on energizing this effort."

Testing and research with B-WIM continues in Alabama and, more recently, in Connecticut. Alabama researchers continue to work with the Slovenian B-WIM System after hosting a B-WIM workshop in Birmingham, AL, in August 2008. Leading European B-WIM experts joined U.S. representatives at this workshop discussing B-WIM performance and areas of advancement in Europe with this technology.

Much was learned in Europe, and opportunities for the United States to improve its truck enforcement programs are progressing as a result of the scan. "The scan identified and recommended several European practices, technology applications, and procedures that have the greatest benefit for adaptation in the United States," says ODOT's Honefanger. "To further assess the practicality of implementation of the scan recommendations, several followup evaluations have been undertaken. The expectation is for vehicle size and weight programs for infrastructure preservation across the country to be radically enhanced and yet be better positioned to meet the growing needs of freight movement."

References

Honefanger, J., et al. (2007). Commercial Motor Vehicle Size and Weight in Europe, FHWA-PL-07-002, Office of International Programs, Federal Highway Administration, U.S. Department of Transportation, Washington, DC.

Jacob, B., O'Brien, E.J., and Jehaes, S. (2004). Weigh-in-Motion of Road Vehicles — Final Report of the COST 323 Action, LCPC, Paris, France.

Office of International Programs (2007). Effective Use of Weigh-in-Motion Data: The Netherlands Case Study, Federal Highway Administration, U.S. Department of Transportation, Washington, DC.

The roadside signing indicates a downstream WIM and vehicle identification site in the Netherlands. Photo: Hans van Saan, Dutch Ministry of Transport, Public Works, and Water Management.
The roadside signing indicates a downstream WIM and vehicle identification site in the Netherlands. Photo: Hans van Saan, Dutch Ministry of Transport, Public Works, and Water Management.

Jodi Carson is an associate research engineer with the Texas Transportation Institute. She has nearly 20 years of experience investigating various aspects of commercial motor VSW enforcement. Carson obtained a Ph.D. in civil engineering from the University of Washington and is a licensed P.E. in Montana and Texas.

Tom Kearney is a transportation specialist with FHWA and recently joined the Truck Size and Weight and Freight Operations and Technology Team in FHWA's Office of Operations. Previously, he was responsible for the New York State Truck Size and Weight Program for FHWA's New York Division. Kearney obtained an M.S. in regional planning from Albany State University.

For more information, see the scanning report at http://international.fhwa.dot.gov/links/pub_details.cfm?id=554 or contact Tom Kearney at 518-431-4125 or tom.kearney@fhwa.dot.gov.

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