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37 a reduction in fuel consumption, emissions, and noise-related safety and highway infrastructure, it often contributes little to costs. However, the full benefits estimated in this study would overall productivity, and it reduces willingness to work for probably not be realized because not all states would allow more comprehensive solutions that could have greater bene- LCVs to operate as widely as assumed in the study. One dif- fits. A regional approach such as the Western Uniformity Sce- ference with this study compared to previous studies is that nario could have greater benefits than a series of individual infrastructure and related costs should not be as great because exemptions, but it also could have much more serious ad- LCVs already operate on at least some highways in each of the verse consequences unless closely monitored. 13 states. So, to a certain extent, states have already consid- It also contended that strong support for the TRB recom- ered LCV size and weight in pavement, bridge, and geomet- mendations in Special Report 267: Regulation of Weights, ric design. Lengths, and Widths of Commercial Motor Vehicles (69) has The study found that few of the states charge enough for not been evident, except for certain segments of the trucking LCV operations to cover the infrastructure costs, and when industry and several states that are interested in size and heavy trucks do not pay their share, other motorists must weight increases. The Department has not taken a formal po- make up the difference. The study recommended that plans sition on the TRB study, partly because it does not favor should be developed for financing those improvements that change in federal truck size and weight policy. However, if include how the longer, heavier trucks would contribute to changes should occur, the U.S.DOT favors strong monitor- paying those costs before making changes in truck size and ing and evaluation as recommended by the TRB study. weight limits that could increase highway improvement Finally, the conclusions emphasize that strong support needs. The report cited a conclusion from TRB Special Report from elected state officials within the region is essential and 267, "federal legislation creating the permit program should critical for successful change in truck size and weight limits. specify a quantitative test for the revenue adequacy of the per- Without such support, it will be difficult to achieve a carefully mit fees imposed by states that wish to participate. . . . Fees controlled and monitored evaluation of changes in truck size should at least cover estimated administrative and infrastruc- and weight limits such as those in the Western Uniformity ture costs for the program . . ." (69). Scenario. Such state support has not been evident to date, and On the critical topic of safety, this report concluded that the there is no compelling federal interest in promoting changes available data are simply not sufficient for developing reliable that are not strongly supported by the affected states. estimates of changes in the number of crashes or fatalities that might result from the proposed changes. States that currently 3.3.6 Research Recommendations allow LCV operation have not noted particular safety prob- and Results lems with LCVs, but they have no formal processes in place to monitor safety. Therefore, one suggestion in the conclusions This section looks at the recommendations of each of the was to require such processes before any substantial changes four studies just discussed, and provides information on re- in federal truck size and weight limits were implemented. An- sults of major recommendations. other suggestion was to consider requirements to ensure that proposed vehicles meet some minimum thresholds for stabil- 3.3.6.1 The Turner Proposal ity and control, and that companies operating these vehicles have good safety records and vehicle maintenance programs. The Turner proposal recommended lower axle group The Western Uniformity Scenario conclusions also point weights and more axles so that a higher gross weight is out some of the salient points of harmonization, which was a achieved, which would require the 36,287 kg (80,000 lb) to central theme of the study. Some of its points favor harmo- be removed (67). Industry did not believe there was enough nization but others appear to justify a more neutral position. payload gain to justify the expense of different equipment, For example, in a statement that seems to justify the status so this major recommendation of the study was not imple- quo, it states that the pattern of truck size and weight limits mented. Most of the other recommendations were contingent that has evolved over the years among states involved in the upon adoption of Turner truck. The recommendation for an- study may not be optimal, but it allows for some appropriate tilock brakes on power units has happened, but due to other regional variation without compromising safety. Somewhat federal safety requirements, none of the other safety recom- to the contrary, it refers to recent state-specific exemptions mendations were adopted. from federal truck size and weight laws that have been enacted, stating that the U.S.DOT does not support a piecemeal ap- 3.3.6.2 The CTSW Study proach. Reasons not to support this approach include: it makes enforcement and compliance with truck size and weight laws The primary goal of the CTSW study was the development more complicated, it may have unintended consequences for and testing of analytical tools to estimate potential diversion