Peer review heavily criticizes DOT's truck size, weight study

By Tyson Fisher, Land Line staff writer | Wednesday, April 23, 2014

An independent peer review by the Transportation Research Board heavily criticizes the DOT’s Comprehensive Truck Size and Weight Limits Study.

The 2012 surface transportation authorization statute requires the DOT to look into truck size and weight limits. 

Last fall, the DOT asked the TRB to review the study and provided it with literature of past studies. Previous studies relevant to truck size and weight were compared and analyzed to determine the effects derived from the changes in truck size and weight.

The effects were measured in five areas: bridges; pavements; truck and rail shares of freight traffic; safety; and enforcement of truck regulations.

According to the TRB review, the past studies used “were not on the critical path of the study,” and that “even in cases where the best practical method is evident, comparisons with alternatives are advisable…” The review also mentions three elements that should be included in the compilation of previous studies and notes how none of the previous studies submitted in the DOT’s study fully provided all three of those elements.

The peer review also criticizes the approach by which the DOT conducted the review and the sources that were used. In none of the five areas to be measured did the DOT explain how their methods and sources were superior to any alternative. Available methods that were used had some major flaws that seem small on the surface but can have major consequences on the impact of new regulations, according to the review. The TRB suggested that the literature does not reveal that any of these flaws have been reduced in the study.

The TRB called the submitted studies “a missed opportunity.” The studies used were said to lack the ability to develop the DOT’s analysis plans. In fact, the peer review went on to suggest that the literature was “prepared after the plans had been decided on,” suggesting a confirmation bias.

Throughout the review, the TRB suggested that many of the study’s flaws could be due to the very limited amount of time the DOT was allotted to complete the study.

This TRB peer review is the first of two reviews to be done on the DOT Comprehensive Truck Size and Weight Limit Study. The first review covers the previous studies prepared by the Federal Highway Administration (FHWA). The second review will analyze the FHWA’s technical analysis. The TRB’s review of the technical analysis is due May 1, 2014.

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