Developing Measures of Effectiveness for Truck Weight Enforcement Activities Final Report (1998) / Chapter Skim
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APPENDIX A Literature Review
APPENDIX A Literature Review
Pages 41-108
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From page 41... ...
The objective of this literature search is to examine documented studies addressing relevant issues related to truck weighing effectiveness, i.e., potential in situ truck weight data sources and appropriate data-gathering technologies, required to establish a program for monitoring truck weight enforcement impacts. BACKGROUND Genera/ Truck Weigh!
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From page 42... ...
Many enforcement officers believe that the off-loading requirement is the most effective deterrent in a truck weight enforcement program. Some of the problems In truck weight enforcement can be attributed to insufficient personnel, usually the result of an insufficient number of budgeted positions for proper operation of permanent and portable scales.
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One strategy to improve the effectiveness of truck weight enforcement effectiveness was suggested in the Wisconsin study by Stein (5)
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Florida currently has 1 3 continuous WIM stations in operation which provides a "wealth" of data. Research investigated optimum number of WIM sites required to address pavement management systems requirements.
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1. Composite data from all highway systems indicate approximately 14% of the 5 Axle Combination Trucks with Trailer were operating with at least 1 possible weight violation and over 6% had gross weight violations.
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Beneft/Need for Truck Weighing Programs Truck weight enforcement programs are both necessary and beneficial. Specific discussed aspects of this issue are the current truck overweight problem, economic impact of truck weight, pavement damage, and safety effects of increased weight.
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A cost-analysis methodology applied in TRB Special Report 225 (9) to estimate Me Impacts of altetnadve Duck weight regulatory scenarios has implications for the development of Muck weight enforcement M.O.E.s.
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A previously cited NCHRP Synthesis (2) noted that without dedicated, persistent truck weight enforcement officers, the highway system would have deteriorated long ago.
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Rigid and flexible pavement structural models were used to obtain pavement "influence functions," which characterize the pavement response to tire loads at any location on the roadway. Fatigue damage to rigid and flexible pavements is most directly detennined by maximum axle loads and pavement thickness.
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to seek implications for effects of truck weight enforcement effectiveness. The methodology applied in TRB Special Report 225 (9)
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However, carriers operating particularly expensive equipment arid those with operations that can benefit only marginally from the new limits could be expected to take appreciably longer to modify their fleet to take hill advantage of the new limits." Pavement impacts were estimated on the basis of costs for new pavements, reconstructed pavements, and pavement rehabilitation. Pavement rehabilitation costs, accounting for the greatest impact, were estimated using (a)
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From page 52... ...
For simplicity, a single-unit cost, $16 per foot-mile, has been chosen for use with both flexible and rigid pavements in estimating the pavement rehabilitation cost impacts of a 1 0 percent increase in traffic loadings. Pavement area by highway class and region was tabulated from FHWA's Highway Performance Monitoring System (HPMS)
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Safer Implications of Enforcement Effectiveness The literature review addressed the documented sensitivity of accident occurrence (in terms of both frequency and severity) with truck weight to seek implications for safety effects of truck weight enforcement effectiveness.
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The base accident rates as reported in TRB Special Report 225 (99 were adjusted for changes in GVW using the following equation: R'= R(!
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TRUCK WEIGHT ENFORCEMENT OPERATIONS The weight and size of commercial vehicles is regulated and enforced for the following two reasons: (1) to avoid excess damage to roadway structures caused by overweight and overheight loads, and (2)
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Assign all size and weight enforcement activity to a special operations unit that is adequately staffed. Establish program needs for use of various scales to ensure reasonable coverage of state systems and apprehension of violators.
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App/icafion of Automated Weigh f Monitoring Procedures Three Oregon papers describe innovative procedures for automating truck weight enforcement activities. The first addresses screening of overweight trucks in the vicinity of Ports of Entry, Me second describes an automated management tool for deploying enforcement personnel, and the Gird relates application of automated vehicle identification technologies.
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Re/evanf Evidence Enforcement Relevant evidence truck weight enforcement is an application of civil rather than criminal law in enforcing truck weight. The procedure involves inspection of relevant documents (receipts, bills-of-laden)
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The forgoing provisions cannot limit the introduction of other competent evidence bearing upon the question of whether or not there is a violation of the prescribed maximum weight limitations permitted by this chapter." Minnesota statute also requires that records be kept for certain overweight loads, and established penalties, by stating: "Record-keeping. A person who weighs goods before or after unloading or a person who loads or unloads goods on the basis of liquid volume measure shall keep a written record of the origin, weight and composition of each shipment, the date of loading or receipt, the name and address of the shipper, Me total number of axles on the vehicle or combination of vehicles, and the registration number of the power unit or some other means of identification by which the shipment was transported.
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Except for records relating to the loading and unloading of We first haul of unprocessed or raw farm products and the transportation of raw and unfinished forest products, a record kept and mat ned as provided In subdivision ~ that shows that a vehicle has exceeded a gross weight I~rnit imposed by this chapter is relevant evidence of a violation of this chapter. The foregoing provisions do not limit the introduction of other competent evidence bearing upon Me question of whether or not there is a violation of the prescribed maximum weight limitation permitted by this chapter.
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The violation rate increased to 18.6% at zero enforcement. A statistical analysis utilizing the t-test indicated that there is a significant difference between the number of overweight trucks at the various enforcement levels.
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Avoidance of overweight is indicated by truck volume (see Exhibit A - 2 and by highway wear, expressed in ESALs (see Exhibit A - 31. The study revealed that the rate of overweight trucks on the mainline decreased 6% during Enforcement Level 1, while the rate of overweight trucks on the major bypass increased 140 percent.
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S.OS-~" AVO"D it/ ) ~- SEC~"Y BYPASS ,l/ / ~FLEX-u~ B - 4SS \ ~" / T - ~82X 6.3X - OTHER NOff-T" AVID -SECONDARY BrP"s 7 NONE- U4JOR BIBS / T~83Z Exhibit A - 2 Observed Wisconsin Scale Avoidance Patterns by Truck Volume 23 Appendix A
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OVERWEIGHT AIMS - 6~ M~ BYPASS \ ACME / T~79: ENFORCEMENT LEVEL 2 > 37.2: - OT - R 2.BY - UA=R B - ASS \ HA - " / T - Usso: / / ENfORCEUENT LEVEL ~ . _ ~ _ >453- OVER - UA~ BYPASS \ ~" ~ T - U-SSX Exhibit A - 3 Observed Wisconsin Scale Avoidance Patterns by ESAL 24 Appendix A
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Accordingly, the state patrol should develop an ability to gauge their truck weight enforcement electiveness based on ESAL's. A logical first step would be more portable weighing activity on the bypass routes coordinated with scale operation.
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7. During Rusk Scale operations, the likelihood of weight violations was ~ times greater on the major bypass route than at the scale.
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The portable WIM was 3 times more reliable than bridge WIM (BWIM) equipment: it lost 5% of total truck traffic due to malfunctions compared to a 14% loss for BWIM." A significant issue raised in the Wisconsin study was the relative effect of pavement wear between the mainline and diversion routes resulting from truck avoidance of weight enforcement.
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is thoroughly evaluating the Wisconsin's truck safety and weight enforcement program. Objectives of the study are: (1)
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Program WIM sites, Pavement/Bridge/Safety Management Systems, the Highway Performance Monitoring System, and Traffic Monitoring Guide data collection sites. A brief explanation of each is as follows.
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Traffic 7. Monitoring The most relevant data modules for application to truck weight enforcement monitoring are the maintenance and traffic modules.
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3. Fatal and Injury Motor Vehicle Accident Data.
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Six-or-More Axle. Single-Trailer Trucks -- All vehicles with six-or-more axles consisting of two units, one of which is a tractor or straight truck power-unit.
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inches per mile statistic derived in the National Cooperative Highway Research Program (NCHRP) 228 Report (26)
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All other roads The estimation of sample size for the truck weight sample is based on the characteristic Equivalent Single Axle Loadings or Loads (ESAL)
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, , 3S2 Trucks (ESAL) \~ lo go so do 50 100 Exhibit A - 4 Pavement/Bridge/Safety Management Systems 200 300 Sample Size Source: Traffic Monitoring Guide The Intermodal Surface Transportation Efficiency Act (ISTEA)
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The data base shall be the source of pavement related information reported to the FHWA for the HEMS in accordance with the HPMS Field Manual. Applicat~ons of Pavement Management Systems The state-of-~e-art is Pavement Management Systems (PMS)
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Virginia has published a series of reports on the progression of their pavement management system (29)
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The condition rating system will provide management with an objective approach to pavement management including documentation of the funding required for maintenance replacement. Bridge management system (BMSJ means a decision support tool that supplies analyses and summaries of data, uses mathematical models to make predictions and recommendations, and provides the means by which alternative policies and programs may be efficiently considered.
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The BMS also has the ability to analyze the data using individual subsystems in order to provide decision support for Department managers. A Bridge Rehabilitation and Replacement Subsystem provides cost estimating and prioritization of bridge improvement projects to support long range planning and programming decisions.
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Highway Safety Management System (SMSJ means a systematic process that has the goal of reducing the number and severity of traffic crashes by ensuring that all opportunities to improve highway safety are identified, considered, implemented as appropriate, and evaluated in all phases of highway planning, design, construction, maintenance, and operation and by providing information for selecting and implementing effective highway safety strategies and projects. SMS data requirements include: (1)
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These data must support an estimation of traffic volume, vehicle classification, and vehicle weight. Specific weight requirements noted in the legislation include "the weights of such vehicles including the weight of each axle and associated distances between axles on a vehicle".
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The purpose of the described Wisconsin program is to collect representative trucking characteristic data for use in pavement design, highway cost allocation, motor carrier enforcement, and other planning and research activities. The use of weigh-in-motion technologies and the emphasis on the collection of basic weight data permit random selection of weigh stations and a comprehensive sample of truck traffic.
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This study analyzed gross weight data of 5-axle semis at five WIM locations. The amount of data available for analysis ("good data")
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These data sources may provide useful information in evaluation of truck weight enforcement activities. Therefore, Exhibit II - 5, assembled by TRB's Committee for the Truck Safety Data Needs Study (26)
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APPLICABLE DATA-COLLECTION TECHNOLOGIES FOR TRUCK WEIGHT ENFORCEMENT M.O.E. DEVELOPMENT The development of truck weight enforcement M.O.E.s is largely dependent on available technologies for detecting truck weights, classification, axle configuration, and vehicle identification.
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Weigh-i~z-Motion ~M) Utilizing WIM systems, truck axle and gross weights of vehicles can be obtained while they are traveling along the highway using in-pavement sensors.
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The Crescent evaluation concluded that application of the technologies produces the following services which have direct application in the evaluation of truck weight enforcement effectiveness. Roadsidle Dimension and Weight Compliance Clearance - Allows state authorities to check the size and weight of commercial vehicles without stopping them.
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, and ultimately, one which watt allow unimpeded passage of trucks across state boundaries. Goals and objectives of the Transparent Borders project are as follows: "Provide documents for each participating state that describe the current regulatory and administrative organizational frameworks within that state as they relate to the creation of transparent state borders for interstate commercial vehicle operations.
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A subsequent evaluation of low-cost WIM alternatives (39) cited data requirements for pavement and bridge design, truck size and weight enforcement, and the development of administrative policy and legislation.
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Results are given regarding the accuracy of the bridge weigh system in three areas: classification, axle spacing and speed, and vehicle axle and gross weights. Enforcement effectiveness is also evaluated.
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B State planning agencies can use traffic volume and weight data for road planning.
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. Telecommunications Devices The Oregon State Highway Division has developed ax Integrated Tactical Enforcement Network or ITEN.
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At other remote sites where there are no permanent weigh stations, the supervisor can deploy his portable scale crews to maximize their enforcement efforts. This could be done on an hourly basis and crews could be deployed to meet the changing truck traffic.
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However, an adaption of this methodology can be specifically geared to truck weight enforcement requirements. Thus, data requirements derived to monitor truck weight enforcement M.O.E.s are as follows.
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3. Due to this presence of observed overweight trucks, Stein recommended that Weigh-InMotion data be utilized as a tool for prioritizing weight enforcement efforts.
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However, in none of these systems did truck volumes or an estimate of actual equivalent single axle loads (ESAL) play a leading role in the determination of expected pavement deterioration rates or pavement rehabilitation prioritization.
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This straight line function intercepts the horizontal axis at C, the point at pavement distress is said to occur. A possible confounding factor in application of a pavement distress function as a truck weight enforcement M.O.E.
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The report notes that road roughness should be considered as a fundamental requirement for a pavement management system. There are a wide range of methods of measurement to evaluate road roughness, either subjectively (ride quality)
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reported that physical distress is a measure of the road surface deterioration caused by traffic, environment and aging. There are no national standards for procedures to be followed or equipment to be used for identifying pavement distress.
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information both from state enforcement agencies and state highway planning agencies. M.O.E.s Suggested by Stale Enforcemenf Agencies Exhibit A -6 lists state truck weight enforcement agency responses to question numbers 6 and 7, stated as follows.
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Candidate Truck Weight Enforcement M.O.E.s M.O.E.s reported by State Enforcement Agencies 61 Appendix A
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Relevant Evidence findings Despite the fact that an introductory letter explaining the nature of the project was sent to state enforcement agencies, it is nevertheless obvious from the above list that certain of the suggested candidate M.O.E.s miss the point of determining what is actually accomplished by the enforcement effort rather than merely indicating a level of enforcement effort. M.O.E.s Based on Paveme'2~/Bridge/Safe~ Management Systems In order to assist in the development of candidate M.O.E.s the state survey asked the following question of state highway planning agencies.
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Nevada None reported. New Hamosh~re IRI for pavements; 15 WIM sites Exhibit A- 8 Measures available from Pavement Management Systems Reported by State Highway Agencies 63 Appendix A
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2. Downs, Hugh G., "Criteria for Evaluation of Truck Weight Enforcement Programs.
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and Fernando, Emmanuel G., "A Microcomputer Procedure to Analyze Axle Load Limits and Pavement Damage Responsibility." Transportation Research Board (~ ~ 987)
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26. Transportation Research Board, Committee for the Truck Safety Data Needs Study, "Data Requirements for Monitoring Truck Safety." Washington, D.C.
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33. Gardner, WD, "Truck Weight Study Sampling Plan in Wisconsin." Transportation Research Board (} 983)
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47. American Association of State and Highway Transportation Officials, Guidle1tines for Pavement Management Systems, July 1990 68 ~ .
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