Research to Support Evaluation of Truck Size and Weight Regulations (2019) / Chapter Skim
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From page 47... ...
47 Appendix A Research Problem Statements PAVEMENT RESEARCH The main traffic input to any pavement design and analysis is truck load ing. Pavement wear increases exponentially with respect to axle weight.
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48 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS have the capability to evaluate a wide range of changes in weights and di mensions, in particular, higher axle load limits, variations in axle groupings and axle spacing, and alternative tire types and sizes. Existing pavement models may not be reliable in predicting pavement response to axle loads, axle groupings, and axle spacing that differ greatly from those in common use.
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APPENDIX A 49 not produce any firm conclusion on the effect of axle configura tion on pavement roughness. The effects of an increasing number of axles and axle spacing on pavement behavior are complex and may not be addressed by the current linear elastic theory, especially for asphalt concrete pavement.
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50 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS total lifecycle cost with respect to equivalent single axle loads (ESALs)
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APPENDIX A 51 TRB committee review of the USDOT 2016 study, predicted service lives from the design software sometimes exceed 50 years, which falls out of the typical service life range of 20 to 30 years. Although a field validation and calibration of the software is being conducted, accurate assessments still will be a challenge because the issue at hand is outside the scope of the currently used approach.
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52 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS PAVEMENT RESEARCH PROBLEM STATEMENT P.1 Realistic assessment of impact of a change in truck size and weight limits on the conditions of pavements of the road network. Problem Statement To reduce the uncertainties in estimates of pavement costs of changes in size and weight limits in the 2016 USDOT truck size and weight study and earlier studies, methods are needed that are applicable to the entire network of local roads and state highways that would be exposed to the traffic of new vehicles (including local roads and roads with overlay pavements)
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APPENDIX A 53 Task 2. If existing methods do not address the aforementioned issues, two options may be considered: • Develop a pavement design and analysis framework, using existing methods, capable of the evaluation previously outlined.
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54 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS PAVEMENT RESEARCH PROBLEM STATEMENT P.2 Method of estimating the effects of a change in truck size and weight limits on highway agency pavement costs and highway user costs. Problem Statement Pavement cost estimates in past truck size and weight studies have depended on assumptions about highway agency responses to changes in the rate of pavement wear on the highway system that are unverified.
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APPENDIX A 55 and axle weight spectra projected in one of the scenarios in the USDOT 2016 truck size and weight study. Data Requirements As noted in the previously stated possible approach.
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56 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS PAVEMENT RESEARCH PROBLEM STATEMENT P.3 Effect of truck platooning on pavement performance and costs, and meth ods to control the effect. Problem Statement With the widespread implementation of intelligent technologies used in autonomous and connected trucks to enable the connection among ve hicles and between vehicles and infrastructure, truck platooning will be more efficient and feasible.
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APPENDIX A 57 Present Status of Research No research has been conducted on the impact of truck platooning on pave ment. Noorvand et al.
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58 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS BRIDGE RESEARCH A change in truck size and weight limits is likely to affect the cost and ur gency of bridge maintenance and construction. An increase in the size and legal weight of trucks may cause highway agencies to post more bridges (that is, to impose weight limits for vehicles using certain bridges that are lower than the normal legal maximum weights)
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APPENDIX A 59 The TRB committee proposed an alternative to the conventional method of estimating bridge costs that the committee believed would be more useful for guiding decisions on truck size and weight limits (TRB 2002, 60–80)
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60 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS to differences in the cost estimates. The AASHTO study report notes the difference with the USDOT 2016 bridge cost estimates, but does not offer a quantitative accounting of the difference.
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APPENDIX A 61 (55 percent of yield stress) ; 22 used the operating rating; and 16 used an inter mediate rating or another method of rating (Hearn 2014, 43)
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62 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS To illustrate the uncertainty introduced in estimates by assumptions about highway agency practices, the TRB Commercial Motor Vehicles com mittee asked a state highway agency to evaluate four structures in the state, selected because they were among the structures with the highest replace ment costs in the 2000 USDOT study's cost estimates. The agency reported that according to its normal practices, it would not replace, strengthen, or post load limits for any of the structures if the new vehicles evaluated by the USDOT study came into use.
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APPENDIX A 63 estimated to decline in a case that assumed substitution of nine axle for fiveaxle configurations. The major cost in both cases was estimated to be the added cost of constructing future new bridges to carry the increased load.
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64 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS B4. Develop a method for estimating the effect of changes in truck size and weight limits on lifecycle costs of bridge decks, including user costs, and for considering the diversity of maintenance practices among state and local highway agencies.
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APPENDIX A 65 BRIDGE RESEARCH PROBLEM STATEMENT B.1 Compile information from state and local highway agencies on costs and treatment selection criteria for bridge deck repair, rehabilitation, and re placement, and for bridge strengthening and replacement. Problem Statement Changes in truck size and weight limits may influence bridge deck mainte nance and replacement, bridge posting, and the need to strengthen bridge spans.
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66 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS projects conducted over a period of years that were motivated at least in part by concerns for damage or structural deficiency in any element of the bridge, and the cost of each project. Records on all bridge postings during the period would also be obtained.
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APPENDIX A 67 Present Status of Research Numerous past studies have developed empirical highway bridge cost esti mating models, although many are more detailed than would be required or practical for the proposed research. Cost models are reviewed in Kim et al.
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68 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS BRIDGE RESEARCH PROBLEM STATEMENT B.2 Develop a model of the effect of wheel loads on bridge deck deterioration and resulting service life, supported by field performance data. Problem Statement Reinforced concrete bridge decks deteriorate over time due to vehicular load history, the environment, and human actions such as the use of deicing salts.
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APPENDIX A 69 The following are three very different possible approaches: 1. Develop a mechanistic model similar to that developed for predic tion of chloride ingress due to diffusion.
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70 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Modes of deck deterioration are characterized in Gucinski et al.
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APPENDIX A 71 BRIDGE RESEARCH PROBLEM STATEMENT B.3 Develop models of the effect of changes in truck size and weight on the most common bridge types, including effect on service life of the main lon gitudinal loadcarrying members or system. Problem Statement An increase in the weights of trucks using a bridge, and especially, increased exposure to loads greater than those the bridge was designed to carry, may reduce the useful life of the main longitudinal loadcarrying members or system.
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72 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS according to engineering theory and the model parameters estimated from the database. The research would consider the 10 most common bridge structure types.
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APPENDIX A 73 3. Create a crosssection or timeseries database with each record corresponding to one bridge in 1 year and including data on loca tion, age, condition measures (from NBI and bridge management systems)
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74 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS The cost of collecting and analyzing field performance data will depend on whether this task can be combined with other research assembling truck traffic data (such as the research outlined in problem statement C.1)
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APPENDIX A 75 BRIDGE RESEARCH PROBLEM STATEMENT B.4 Develop a method for estimating the effect of changes in truck size and weight limits on lifecycle costs of bridge decks, including user costs, and for considering the diversity of maintenance practices among state and local highway agencies. Problem Statement The deck deterioration and structure deterioration models, unit cost data, and synthesis of state decisionmaking practices developed in the research outlined in problem statements B.1 and B.2 would supply the tools to make credible projections of bridgerelated costs in a truck size and weight limits study.
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76 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS 4. Estimate associated user delay costs according to the volume and mix of traffic on each bridge.
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APPENDIX A 77 BRIDGE RESEARCH PROBLEM STATEMENT B.5 Develop a method for estimating the effect on bridge lifecycle cost of the change in deterioration and service life and in risk of loss of functionality caused by a change in truck size and weight limits. Problem Statement The research outlined in problem statement B.3 would develop a model for each common bridge type of the effect of an increase in the weights of trucks using a bridge on the loss of useful life of the bridge through deterio ration of bridge elements other than the deck.
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78 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Possible Approaches The research approach would be analogous to the approach for estimating bridge deck costs outlined in problem statement B.4. A dataset of bridges used for the research should be nationally representa tive of the 10 to 12 most common bridge types, age distribution, length of spans, rural versus city location, and state versus local ownership.
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APPENDIX A 79 service life of bridges not treated. Past truck size and weight studies were unable to make such comparisons because they lacked a model for costs of deterioration of bridges that were not strengthened, replaced, or posted.
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80 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS BRIDGE RESEARCH PROBLEM STATEMENT B.6 Develop a replacement for the "Formula B" provision in federal size and weight law that more appropriately controls weights of short, heavy vehicles. Problem Statement Formula B is a mathematical equation, table, and series of footnotes that make up part of the federal weight and size regulations about interstate commercial traffic on bridges.
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APPENDIX A 81 Data Requirements Data are required for bridge loads and bridge resistance. A survey of com mercial carriers and state permitting practice may be of assistance in terms of loads.
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82 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS BRIDGE RESEARCH PROBLEM STATEMENT B.7 Develop a revised deck design load and permit design load and calibrate load factors for both. Calibrate load factors for bridge evaluation that ac count for varying levels of law enforcement.
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APPENDIX A 83 2. A practical but improved design methodology for conventionally reinforced, prestressed, and posttensioned concrete decks.
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84 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Estimated Cost and Research Period Research period: 30 months Cost: $300,000 Priority This research project is needed in response to increased truck size and weight for the appropriate design of girders and decks in new bridges. Improvement of deck design methodologies is ancillary but could lead to justification of higher axle loads.
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APPENDIX A 85 SAFETY RESEARCH The safety impact of a change in truck size and weight regulations is the change in the frequencies of crashes and crash casualties occurring on the highway system resulting from the change in the regulations. Crash fre quency may change because the volume of truck traffic and the distribution of truck traffic across the road system change and because new truck types may have inherently different crash risk per mile of travel than the trucks they replace.
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From page 86... ...
86 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS support safety analyses in truck size and weight studies, and support evalu ation of ways to reduce crash risks: S.1 Enhancement of crash and exposure data for application in a re search environment. S.2 Comparative evaluations of differences in safety performance among truck configurations by measurement of crash involvement rates on a network of roads.
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APPENDIX A 87 Potential Bias Due to Lack of Specific Data Types (Limitations 1 through 4) Limitations 1 through 4 reflect the current nature of data systems in most states.
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88 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Thus, if the actual difference in crash rate between two truck types is as large as 50 percent, relatively modest amounts of data can identify the difference as statistically significant. If the actual difference in crash rate between two truck types is small (for example, 5 percent or 10 percent)
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From page 89... ...
APPENDIX A 89 of truck safety will come from the cumulative experience of studies using diverse methodologies, conducted in a variety of settings. Results of vehicle dynamics simulation modeling and test track evalu ations can be used to investigate possible sources of differences in safety performance among existing or proposed truck configurations.
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90 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS SAFETY RESEARCH PROBLEM STATEMENT S.1 Enhancement of crash and exposure data for application in a research environment. Problem Statement A key limitation for comparative studies of the safety performance of truck configurations is the lack of complete and accurate data on truckinvolved crashes and truck exposure (vehiclemiles of travel)
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APPENDIX A 91 how to complete the form. Accurate classification of truck configuration is challenging.
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92 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS • Exposure data elements: – Truck configuration for each truck counted in exposure stud ies (based on number and length of tractor and trailer units, number and spacing of axles, and types of hitch connections between tractors and trailers)
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APPENDIX A 93 data collection would cost approximately $450,000–$650,000 over 16–24 months. In addition to these funds, the research would depend on inkind contribu tions of staff time and equipment from the participating agencies.
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94 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS SAFETY RESEARCH PROBLEM STATEMENT S.2 Develop and demonstrate a method to conduct routebased or networkbased comparative evaluations of the safety performance of truck configurations. Problem Statement Comparative evaluations are conducted to quantify the difference in safety performance measures (crash involvement rates and crash severity distri butions)
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APPENDIX A 95 This problem statement describes routebased and networkbased evalua tions. Problem statements S.3 and S.4 describe casecontrol evaluations and evaluations that use trucking company data, respectively.
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96 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS (1986) were previously described in the introduction to the safety problem statements.
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APPENDIX A 97 SAFETY RESEARCH PROBLEM STATEMENT S.3 Develop and demonstrate a method to conduct comparative evaluations of safety performance of truck configurations using the casecontrol study design method. Problem Statement Same as for problem statement S.2.
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98 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Data Requirements Crash data would be collected specially for the study. The method would be the same as that for problem statement S.2.
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APPENDIX A 99 SAFETY RESEARCH PROBLEM STATEMENT S.4 Develop and demonstrate a method to conduct comparative evaluations of the safety performance of truck configurations using trucking company data. Problem Statement Same as for problem statement S.2.
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100 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS If such a study were conducted as a government initiative, the first step would be to define the objective, in terms of the configurations and operations to be compared, and the general method of the evaluation. Then trucking compa nies and industry associations would be recruited to participate.
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APPENDIX A 101 Road trials of alternative configurations in Europe (described in this com mittee's first report [TRB 2018, 13–14]
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102 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS SAFETY RESEARCH PROBLEM STATEMENT S.5 Evaluate the potential safety performance of specific truck configurations using computer simulation modeling and test track evaluations. Problem Statement Comparative evaluations, as described in problem statements S.2, S.3, and S.4, can only be performed for truck configurations that are in use.
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APPENDIX A 103 and data collection and analysis methods of trials; design an administrative structure; and finally conduct selected evaluations as a demonstration of the procedures. Past research has identified safetyrelated measures of truck performance that can be quantified for proposed new truck configurations and com pared to the performance of existing truck configurations.
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104 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Estimated Cost and Research Period The cost of a study to develop and demonstrate a standard procedure for simulation and test track evaluation of vehicle handling and stability for the applications previously identified would be approximately $500,000– $700,000. An estimated $1,000,000–$3,000,000 over a 3year period would be needed to conduct simulations and test track evaluations for the various configurations that have been proposed recently by industry or considered in recent truck size and weight studies.
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APPENDIX A 105 SAFETY RESEARCH PROBLEM STATEMENT S.6 Develop a model to project the frequency of crashes on a road as a function of the vehicle mix and traffic volume on the road. Problem Statement The method commonly used in past truck size and weight studies to project the systemwide safety impact of a change in limits has been to assign each vehicle type a fixed crash involvement rate for each road functional class.
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From page 106... ...
106 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Present Status of Research The model of crash frequency on a road segment versus traffic volume that was explored in the USDOT 2016 truck size and weight study (FHWA 2015d, 21–23, 27–30) is an example of the basic approach of this research.
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APPENDIX A 107 ENFORCEMENT RESEARCH An evaluation of changes in truck size and weight limits must consider the interactions between regulations and size and weight limit enforcement. The characteristics of trucks on the road are determined by the combined influ ence of legal limits and enforcement effectiveness.
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From page 108... ...
108 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS discrete activities -- for example, the costs of weighings, safety inspections of vehicles, and logbook inspections -- would be most useful. A thorough understanding of enforcement costs and effectiveness would allow admin istrators to redirect resources to better meet the objectives of safety and control of infrastructure costs.
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APPENDIX A 109 ENFORCEMENT RESEARCH PROBLEM STATEMENT E.1 Relationship between enforcement effort and compliance with size and weight laws. Problem Statement Projections of effects of changes in truck size and weight limits depend criti cally on assumptions about the effectiveness of enforcement of existing and proposed regulations.
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110 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS weight data for a group of states by highway class, preferably for a period of years. The weight data may be the product of research under problem statement C.1.
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APPENDIX A 111 Data Requirements As previously described, data requirements are data at the state level, or state and road class level, on (1) enforcement effectiveness as indicated by gross weight and axle weight data for the highway system, (2)
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112 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Priority The research results would be useful in evaluations of truck size and weight limits because the impact of changes in limits will depend on the effective ness of enforcement before and after the change. Changes in enforcement practices in coordination with changes in limits would be a means of miti gating the costs of the changes.
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APPENDIX A 113 ENFORCEMENT RESEARCH PROBLEM STATEMENT E.2 Detailed accounting of truck size and weight enforcement costs. Problem Statement Changes in truck size and weight regulations could affect the costs of enforcement.
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114 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS to changes in enforcement procedures necessitated by changes in size and weight regulations. Data Requirements State enforcement agencies already collect much of the data that the survey would request.
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APPENDIX A 115 ENFORCEMENT RESEARCH PROBLEM STATEMENT E.3 Survey of truck size and weight enforcement and regulations in other countries. Problem Statement Several industrialized nations have enacted significant revisions in their motor vehicle size and weight regulations in recent decades.
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116 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Data Requirements As previously noted. Present Status of Research Various past surveys provide a starting point for research.
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APPENDIX A 117 ENFORCEMENT RESEARCH PROBLEM STATEMENT E.4 Design and conduct pilot studies to evaluate alternative methods of enforc ing weight and dimension regulations, including information technology applications and automated enforcement. Problem Statement Effective enforcement of size and weight regulations is critical for control ling wear and damage to pavement and bridges and for reducing crash risk.
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118 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS The measure of effectiveness would be WIM records of vehicle and axle weight distributions on the roads within the test areas. Availability of weight data would be a factor in selecting states and designing the ex periments.
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APPENDIX A 119 Priority Enforcement pilot projects, either standalone or as part of a comprehensive evaluation of truck size and weight regulation, should be high priorities because of the importance of enforcement to controlling the costs of truck traffic. Developing and conducting pilots would be a relatively longterm effort.
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120 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS MODE AND VEHICLE CHOICE AND FREIGHT MARKET RESEARCH Changes in truck size and weight regulations will change the truck configu rations available to shippers and transportation companies and their rela tive costs. These firms will change their freight mode and vehicle choices in response.
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APPENDIX A 121 models can be divided into two families: econometric and supplychain based models. The former use econometric techniques to capture the deci sion dynamics at the core of the freight mode/vehicle choice process, while the latter replicate the chain of decisions that minimizes logistical costs (transport plus inventory costs)
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From page 122... ...
122 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS truck types for a subsample in the next CFS survey or by conducting a sepa rate survey. A separate survey would be more practical in the short term, but estimating DCMs of freight mode/vehicle choice with the data from a single survey would eliminate concerns about data comparability that arise when different samples are used.
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APPENDIX A 123 Research Problems A research program made up of the following projects would be consistent with previously stated considerations and would provide methods for US DOT to project freight market effects of changes in truck size and weight limits that would be useful for policy analysis: M.1 Adaptation and testing of freight mode choice models for applica tion in truck size and weight limit policy studies. M.2 Development of a mode and vehicle choice model for application in truck size and weight limit policy studies.
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124 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS MODE CHOICE RESEARCH PROBLEM STATEMENT M.1 Adaptation and testing of freight mode choice models for application in truck size and weight limit policy studies. Problem Statement Estimates of all categories of impact in prospective evaluations of changes in truck size and weight limits depend on projections of the changes in truck traffic that the change in limits will stimulate.
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APPENDIX A 125 of freight market researchers and industry experts to review the model comparisons.
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126 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS MODE CHOICE RESEARCH PROBLEM STATEMENT M.2 Development of a mode and vehicle choice model for application in truck size and weight limit policy studies. Problem Statement Changes in truck size and weight regulations may induce changes in ship pers' choices of both mode and truck type: the nature and extent of these changes determine the infrastructure, safety, and other impacts of the regu latory change.
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APPENDIX A 127 2. Collect a sample of revealed preference or stated preference data to support model estimation.
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128 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS costs, length of haul, and state size and weight restrictions. The model was estimated with disaggregate data from the Census Bureau's Truck Inventory and Use Survey, supplemented with vehicle capital and operating cost data from other sources (Small et al.
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From page 129... ...
APPENDIX A 129 Priority An improved method of projecting the effect of changes in size and weight limits on mode and vehicle choice would enhance the credibility and use fulness of projections, in a comprehensive truck size and weight study, of all other effects of changes in the limits. In addition, an improved method would be useful for evaluating changes in user fees and other policies to mitigate truck costs and improve freight transportation efficiency, regardless of whether truck size and weight limits are changed.
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130 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS MODE CHOICE RESEARCH PROBLEM STATEMENT M.3 Development of a method of projecting railroad industry revenue impact, including revenue impacts for shortline railroads, of mode shifts caused by changes in truck size and weight limits. Problem Statement Past federal truck size and weight studies have considered the effects of changing size and weight limits on railroad industry revenue and profits among the impacts considered to be significant for assessing policy alterna tives.
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APPENDIX A 131 3. Assess the effects of size and weight limit changes on the traffic and revenue of shortline railroads by individually analyzing a sample of short lines.
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132 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Estimated Cost and Research Period Cost and duration will depend on the scope of data collection for the esti mation of shortline financial impacts. Cost: $200,000 to $450,000 Research period: 12 to 24 months Priority Assessment of potential rail industry impacts has always been necessary in federal truck size and weight studies and has been a factor in legislative decisions on the regulations.
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APPENDIX A 133 CROSS-CUTTING TOPICS; EVALUATION OF REGULATORY OPTIONS The problem statements presented in this section are for research on topics other than the development of specific impact models to support evaluation of truck size and weight regulations. The first topic is to provide the truck traffic data needed for projections of all categories of impacts.
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From page 134... ...
134 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS CROSS-CUTTING TOPICS RESEARCH PROBLEM STATEMENT C.1 Develop truck traffic, weight, and configuration databases necessary for truck size and weight research and evaluations. Problem Statement Data on combination vehicle and heavy singleunit truck traffic volume and axle weight spectra by configuration type are necessary for the research on infrastructure, safety, and freight market impacts outlined in the previous sections.
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APPENDIX A 135 gross weight distributions by configuration for the United States and for individual states by road system. Developing useful weight data for local roads will be a major challenge.
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136 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Early completion would facilitate other research in the roadmap. If the research were extended to include new data collection on local roads, cost and duration would be greater.
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APPENDIX A 137 CROSS-CUTTING TOPICS RESEARCH PROBLEM STATEMENT C.2 Develop methods for incorporating common features of regulatory schemes in evaluations of the costs and benefits of changing truck size and weight limits. Problem Statement The 2016 USDOT truck size and weight study defined each of the scenarios evaluated in terms of a single specified truck configuration and the road network on which the truck was assumed to operate.
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From page 138... ...
138 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Research Objective The research would develop methods to evaluate supplemental restrictions on the use of new vehicles, including route restrictions, bridge postings (blocking new vehicles from using certain bridges that are open to vehicles meeting the present size and weight limits) , and adjustments in truck user fees and taxes to match the infrastructure costs occasioned.
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From page 139... ...
APPENDIX A 139 The effects of changes in truck user fees and taxes (including fuel taxes, registration fees, federal use tax and excise taxes, and tolls) on the use of new vehicles could be estimated with the freight mode and vehicle choice model developed in the research outlined in problem statement M.2.
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From page 140... ...
140 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS CROSS-CUTTING TOPICS RESEARCH PROBLEM STATEMENT C.3 Develop an analysis framework for evaluating the potential to coordinate size and weight regulations with other road management policies (user fees, enforcement of regulations, road and bridge design, and asset management) to increase public benefits from the road system.
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From page 141... ...
APPENDIX A 141 Canadian Vehicle Weights and Dimensions Study (RTAC 1986) is an exam ple of an evaluation of the coordination of truck size and weight limits with safety regulation, through the mechanism of performancebased standards.
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142 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS models developed in other research outlined in this roadmap. The freight mode/vehicle choice model developed in project M.1 would be applicable to projecting effects of changes in user fees.
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APPENDIX A 143 • The Brookings Institution study Road Work (Small et al.
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144 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS CROSS-CUTTING TOPICS RESEARCH PROBLEM STATEMENT C.4 Develop protocols for conducting staged road trials of truck configurations. Problem Statement Projections of the outcomes of regulatory changes based on historical experience cannot be highly reliable, even if models are greatly refined, because of the complexity of the highway freight transportation system.
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APPENDIX A 145 Observation of effects on pavement might be possible in a largescale, long duration trial. Effect on bridge durability probably would not be observable in a trial of practical scale.
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146 EVALUATION OF TRUCK SIZE AND WEIGHT REGULATIONS Priority A trial program may be the best method for verifying the findings of com puter simulation modeling and test track evaluations. A road trial could also provide information to check predictions of infrastructure and enforcement impacts and carrier acceptance of alternative configurations.
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