COMMERCIAL MOTOR

VEHICLE Size Enforcement lthough few states explicitly record such events, tunnel or bridge/overpass “hits” by oversize commercial motor vehicles (CMVs) result in costly and time-consuming infrastructure repairs, possible injuries or fatalities for the involved driver or other motorists, and considerable traffic delays and associated excess fuel consumption and emissions. Single events occurring in Maine, Oregon, Washington, and Wisconsin reportedly resulted in between $150,000 to $350,000 in infrastructure damage, roadway closures lasting from two weeks to two months, and traffic detours up to 45 minutes in length. The State of New York reports up to 200 tunnel or bridge/overpass hits annually.

Transportation and law enforcement agencies in the U.S. are challenged to effectively and efficiently enforce CMV size. Not every vehicle can be assessed for size compliance; observing only a portion of the traffic stream, an enforcement official must subjectively determine whether to stop a vehicle and what measurements are required. Typically relying upon the use of a measuring tape or bar, some aspects of vehicle size - such as the highest point of an irregular load - are difficult for an enforcement official to physically or safely determine. This process of capturing size measurements is also prone to human error and time-consuming, keeping personnel from performing other enforcement duties.

During the 2006 Commercial Motor Vehicle Size and Weight Enforcement Scanning Study - sponsored by the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the National Cooperation Highway Research Program - a team of U.S transportation experts observed notable technology-based European enforcement policies and procedures leading to enhanced efficiency and effectiveness in size enforcement operations.

This informational brief describes these policies and procedures and considers the potential for U.S. application, including the necessary supporting technologies and opportunities for incremental implementation. Anticipated benefits and associated cost savings related to operational enhancements, infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also described.

Although CMV size and weight enforcement activities are often performed concurrently by enforcement officials, opportunities to improve CMV size enforcement are exclusively addressed here. Opportunities to improve CMV weight enforcement are described in a companion publication, Commercial Motor Vehicle Weight Enforcement, available at http://www.trb.org.

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Requested By: AASHTO Standing Committee on Highways

Prepared By: Jodi L. Carson, P.E., Ph.D., Texas A&M Research Foundation on behalf of Texas Transportation Institute, Texas A&M University System, College Station, Texas

Project Information: The information contained in this report was prepared as part of NCHRP Project 20-07, Task 254, Vehicle Size and Weight Management Technology Transfer and Best Practices. National Cooperative Highway Research Program, Transportation Research Board, http://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=2335

OCTOBER 2008

Notable Policies and Procedures Transportation and law enforcement agencies in Europe have developed various technology-based systems and supporting procedures to enhance the efficiency and effectiveness of CMV size enforcement with unique motivations related to infrastructure preservation, pre-selection for manual enforcement, and direct enforcement.

Both Switzerland and The Netherlands utilize technology to enhance CMV size enforcement with a focus on infrastructure preservation. As part of a larger system for remote Alpine region tunnels, the Swiss use roadside infrared sensors placed upstream of tunnels to determine vehicle height. If the sensors identify a vehicle as overheight (i.e., if the infrared beam, projected at a threshold height across the lanes of

travel, is interrupted by a vehicle), a red traffic signal indication is activated directing the driver to divert from the current route. With a similar focus on tunnel preservation, the Dutch are experimenting with joint height detection/weigh-in-motion (WIM) systems in an effort to reduce overall implementation costs. One early finding is that the best locations for height detection systems (e.g., preceding tunnels) do not often correspond to the best locations for WIM systems; combined systems may not prove cost-effective.

Similar systems are currently in use in the U.S. Along the New York State Thruway, roadside infrared sensors monitor CMV height upstream of an E-ZPass toll plaza. If an overheight CMV is detected, an audible alarm sounds, the E-ZPass CMV lanes are closed, and all vehicles are directed to a booth where the overheight vehicle is identified. The Maine Department of Transportation operates a similar system upstream of an overpass along I–395 in Bangor. Roadside infrared sensors are used to detect overheight vehicles. Dynamic message signs warn drivers of their overheight status and communicate appropriate action (i.e., divert from current route). An alert email is also sent to Maine Department of Transportation staff. Unique to this system, video and photo devices are used to record silhouette and license plate images of the offending vehicle. According to the 2006 Intelligent Transportation Systems (ITS) Deployment Survey, 23 U.S. states report using some type of overheight detection and warning system.

Germany relies upon more advanced technology and supporting pre-selection procedures to enhance CMV size enforcement. Utilizing laser scan technology, a gantry-mounted vehicle profiler system

provides a full three-dimensional profile (i.e., height, width, and length) of a vehicle. Two laser scanners mounted on the first gantry capture vehicle height and width measurements and a third scanner mounted on a second gantry captures vehicle length. As a vehicle passes under the gantries, accompanying software creates a three-dimensional model of the vehicle that can be rotated in any direction for analysis. Size dimensions exceeding legal allowances are highlighted in red.

More than 300 gantries – which include additional technologies to support vehicle identification and tolling - are installed along 12,000 kilometers (7,456 miles) of German autobahn as part of its larger Toll Collect system. The Germans measure CMV size at high speeds to pre-select potentially oversized vehicles from the traffic stream. If a vehicle is identified as potentially oversized, vehicle silhouette and license plate images captured at the gantries are sent downstream using dedicated, short-range communications (DSRC) to mobile enforcement units. Roving enforcement personnel direct the driver off-route for manual measurement and subsequent enforcement action.

Switzerland has incorporated the use of the same gantry-mounted vehicle profiler system as part of an efficient and effective approach to simultaneously measuring CMV size and weight at off-route stationary enforcement locations (i.e., heavy goods vehicle control centers). Mobile enforcement units escort

potentially oversize or overweight vehicles - based on mainline WIM data (for potentially overweight CMVs) and/or enforcement personnel assessment (for potentially oversize or overweight CMVs) - into the facility for additional measurements. Once inside the facility, vehicles are directed to drive under the gantries at speeds less than 5 kph (3 mph) and onto a static weigh bridge instrumented with several load cell scales that provides simultaneous axle and gross vehicle weight measurements. Size- and weight-related citations are generated automatically on-site for issuance to the driver and submission to the appropriate judiciary body. The driver may also be required to offload the vehicle before proceeding.

Allowable measurement tolerances used when issuing citations are as follows: 5 cm (1.97 in) for height, 4 cm (1.57 in) for width, and 10 cm (3.94 in) for length. The vehicle profiler system was tested for two years to ensure adequate performance and was first certified for direct enforcement in 2006 by the Swiss Federal Office of Metrology.

Infrastructure Preservation

Pre-selection

Direct Enforcement

Unique Partnerships An overarching factor contributing to the success of many of the European policies and procedures for CMV size and weight enforcement is the high level of collaboration between similar agencies of different jurisdictional levels (e.g., national and regional law enforcement agencies) and between different agencies (e.g., transportation and law enforcement agencies).

In The Netherlands, for example, primary responsibility for CMV size and weight enforcement rests with the Ministry of Transport and National Police Agency. To ensure that CMV size and weight enforcement is a continued and consistent priority among the two agencies, the Ministry of Transport funds approximately 100 additional limited capacity police officers (trained in 80% of full police officer duties) who focus their time on weight enforcement and congestion/incident management activities. In addition, these two agencies work closely with the Transport Inspectorate, who monitors and enforces regulations on vehicle insurance, fleet maintenance, vehicle safety, and environmental conditions and Public Prosecution Service, who ensures that confirmed CMV size and weight regulation offenders are called to account with the law. Transportation and law enforcement agencies in the U.S., responsible for CMV size and weight enforcement, often do not share the same level of collaboration.

Supporting Technologies

Functions

• Detects overheight vehicles using infrared, laser, or other sensor technology. • Alerts driver of overheight status, recommends action through static signs/flashers, audible

alarms, and/or dynamic message signs.

Considerations

• Provides 24/7 monitoring. • Relies upon drivers to self-correct. • May experience false alarms. • Audible alarms may not be heard by driver and/or may disturb area businesses/residents.

Overheight Vehicle Detection System

• Height Sensors • Driver Communication

System

Estimated Costs

• $25,000 - $125,000 per system/approach. • Varies based on driver communication technologies, on-site communication requirements.

Functions

• Captures both vehicle silhouette and license plate images using cameras. • Converts license plate image to numeric data using OCR software. • Transmits images/data via DSRC to portable computer used by enforcement officials.

Considerations

• Conversion of some license plate images to numeric data may result in errors.

Vehicle Identification System

• Camera/ OCR Software

• DSRC/ Portable Computer Estimated Costs

• $52,000 - $80,000 per system. • Varies based on camera type, on-site communication requirements.

Functions

• Provides three-dimensional profile of vehicle. • Supports pre-selection at high and direct enforcement at low vehicle speeds.

Considerations

• Provides 24/7 monitoring in high-speed applications. • May be combined with fixed weigh facilities. • At <5 mph, achieves accuracies of ±5 cm (1.97 in) in height, ±4 cm (1.57 in) in width, and

±10 cm (3.94 in) in length.

Vehicle Profiler System

• Height, Width, Length Sensors

• Citation Generation System

Estimated Costs

• $250,000 per system.

Incremental Implementation Steps

INFRASTRUCTURE

PRESERVATION PRE-SELECTION

DIRECT ENFORCEMENT

Vehicle Profiler System

Vehicle Identification System

Overheight Vehicle Detection System

Interface with Other Functional Areas BRIDGE

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WIM SYSTEM

CALIBRATION

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SUPPORTING TECHNOLOGIES

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Vehicle Identification System

Advanced Routing/Permitting System

Vehicle Profiler System

Bridge WIM System

In-road WIM System

Dynamic Calibration Vehicle

Overheight Vehicle Detection System

Height, Width, Length Sensors

Citation Generation

Driver Communication

Height Sensors

DSRC

Cameras/OCR

Driver Communication

Height Sensors

Perceived and Reported Benefits Operational benefits attributable to the observed technology-based CMV size enforcement policies and procedures are largely anecdotal. Swiss enforcement officials report overall time savings, greater accuracies, higher certainty in court, and the ability to process a higher volume of CMVs using the vehicle profiler system. System accuracy has rarely been challenged in court and has been readily defensible when called into question. Despite gains in efficiency, two officials continue to be used per site; the vehicle profiler technology has simply freed up personnel time for other enforcement duties.

Broader benefits related to infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also not well-documented but could prove significant in the U.S. With single tunnel or bridge/overpass “hit” events resulting in $150,000 to $350,000 in infrastructure damage and single states reporting up to 200 events annually, the cost savings attributable to the use of technologies to enhance CMV size enforcement could quickly offset the cost of investment. Associated cost savings related to reductions in primary and secondary incident risks, congestion, and harmful emissions resulting from resultant roadway closures (reportedly lasting up to two months with traffic detours up to 45 minutes in length per event) could also be substantial.

Disclaimer: The opinions and conclusions expressed or implied are those of the research agency that performed the research and not necessarily those of the Transportation Research Board or its sponsors. The information contained in this document was taken directly from the submission of the

author(s). This document is not a report of the Transportation Research Board or of the National Research Council.