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2 INTRODUCTION In April 2016, USDOT delivered to Congress the final report of its Comprehensive Truck Size and Weight Limits Study (FHWA 2016a), meeting a requirement of the Moving Ahead for Progress in the 21st Century Act (MAP-21) of 201. The act called for a study to compare the impacts of truck traffic operating under present federal regulations with the impacts if configurations exceeding present limits were allowed to operate, in terms of effects on safety, infrastructure, cost responsibilities, fuel efficiency, freight transportation costs, the environment, truck traffic volumes, and shares of freight traffic carried by trucks and other freight modes. The act also required an evaluation of the frequency of violations of federal truck size and weight regulations and the cost and effectiveness of enforcement. In 2015, USDOT published the results of its technical analysis of the effects of changing limits in the five areas of safety, bridges, pavements, modal competition, and enforcement and compliance (FHWA 2015). Also in 2015, TRB published a review by a TRB committee of the technical analysis, conducted at the request of USDOT (TRB 2015). The USDOT final report did not contain recommendations for changes in federal truck size and weight regulations. The study did not produce national estimates of safety or infrastructure impacts of changes in the limits. In the letter transmitting the technical analysis to Congress, USDOT described the limitations of the analysis as follows (Rogoff 2015): At this time, the Department believes that the current data limitations are so profound that the results cannot accurately be extrapolated to predict national impacts. As such, the Department believes that no changes in the relevant truck size and weight laws and regulations should be considered until these data limitations are overcome.
3 Data limitations cited as examples in the transmittal letter included insufficient information about trucks in crash records, especially a lack of weight information; lack of understanding of the effects of truck traffic on bridge deck deterioration; and lack of truck weight enforcement cost data. In its final report to Congress, USDOT repeated this conclusion and recommended continuing the research (FHWA 2016a, 21): To make a genuine, measurable improvement in the knowledge needed for these study areas, a more robust study effort should start with the design of a research program that can identify the areas, mechanisms, and practices needed to establish new data sets and models to advance the state of practice. Subsequently, the Federal Highway Administrationâs (FHWAâs) Office of Freight Management and Operations asked TRB to develop a plan for the research program that was called for in the USDOT final report. In response, TRB organized the Truck Size and Weight Limits Research Plan Committee, which was charged with the following task: This project will develop and recommend a research roadmap to address gaps and uncertainties in estimating the impacts of changes in truck size and weight limits. Specific research projects, estimated costs, and timelines will be recommended in the areas of safety, compliance/enforcement, modal shift, bridges, and pavements. The recommendations will include efficient means of collecting data essential to estimating the impacts of larger and heavier trucks in these five areas on national, state, and local roads. In addition to a final report presenting the committeeâs research roadmap, FHWA asked TRB for this interim report from the committee, with the following contents:
4 ï· A preliminary list and description of research and data needs and objectives in each of the five topical areas (safety, enforcement, modal shift, bridges, and pavement) derived from research from the 2016 USDOT study, the 2015 TRB committee review of that study, earlier truck size and weight studies, and also reflecting recent developments not considered in the 2016 USDOT study. ï· A description of the framework or process that the committee will follow for setting priorities among the inventory of research and data needs and for defining the appropriate roles of USDOT and other possible participants in research and data collection. For each of the research topics that the committee decides to include in its plan, the committeeâs final report will provide a research problem statement specifying the product, participants, and anticipated scale. Following the example of research plans on road transportation topics that the committee has reviewed (ITS Joint Program Office 2015, Shladover and Gettman 2015), the elements of the research plan will include: ï· A statement of the objectives of the government activities that the research will support and the relevance of the research results to those objectives ï· A schedule indicating the sequence of research projects and estimated time requirements ï· A definition of program tracksâeach track will be a series of interrelated research projects and supporting activities that will require coordination ï· Research problem statements within each track and phase This interim report describes only the candidate topics for the research problem statements in the plan. It does not contain recommendations. Statements about research priorities are preliminary and may differ
