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Chapter XI


Western Uniformity Scenario Analysis graphic depicting western states and illustration of longer combination vehicle

Study Conclusions

Longer combination vehicles have been operating in 13 Western States for many years. Size and weight limits in those States vary as does the extent of the highway network on which LCVs can operate. Some of these differences are due to federal truck size and weight limits, especially grandfather rights under which States can allow vehicles exceeding 80,000 pounds to operate on Interstate Highways. But some of these differences also reflect differences among the States in the vehicle weights and dimensions they believe are appropriate for their highway systems. If States were given the flexibility to increase their truck size and weight limits to levels assumed in this scenario, some States immediately would take full advantage of this flexibility, others might change some but not all size and weight limits, and several might not change truck size and weight limits at all.

Like previous studies that have examined the potential impacts of changing truck size and weight limits, this study has estimated substantial shipper benefits from allowing more widespread use of LCVs. Other benefits from the changes in truck size and weight limits assumed in this scenario are reductions in fuel consumption, emissions, and noise-related costs. The full benefits estimated in this study likely would not be realized, however, because all States would not allow LCV to operate as widely as assumed in this study.

Infrastructure and related costs would not be as great as has been estimated in previous studies because LCVs already operate on at least some highways in each of the 13 States included in the analysis. Thus to a certain extent States have already considered LCV weights and dimensions in pavement, bridge, and geometric design. Nevertheless improvements costing several billion dollars were estimated to be needed to correct deficiencies in bridges, interchange ramps, and other highway elements just to accommodate existing truck operations. These deficiencies may not be severe enough to require immediate improvements, but in the long run would likely have to be corrected, especially if LCV volumes increased. If LCV operations expanded under assumptions in this scenario, added infrastructure costs could be from about $300 million to more than $2 billion. Several factors would affect the magnitude of these additional infrastructure costs including the extent to which States allowed larger LCVs to operate, the length limits imposed on double trailer combinations, and the extent to which bridges can be strengthened rather than replaced. Some States may continue to defer non-essential costs as they have done under current truck size and weight limits, but doing so ultimately may increase costs and could increase safety risks as well.

Few Western States charge fees that cover the infrastructure costs associated with LCV operations. The significant exception is Oregon that routinely conducts highway cost allocation studies to estimate the cost responsibility of various truck classes and adjusts truck-related fees according to results of those studies. When LCVs and other heavy trucks do not pay the full costs of their operations, other motorists must make up the difference. This is inequitable to the highway users who must subsidize LCV operations and contributes to an uneven playing field for railroads and other competitors. States already are experiencing budgetary problems as they look to improve the condition and performance of their transportation systems, and Federal Highway Trust Fund revenues to support the Federal-aid highway program have been growing more slowly in recent years. Before any action is taken with respect to changes in truck size and weight limits that could increase highway improvement needs, plans for financing those improvements should be developed that include how the longer, heavier trucks responsible for additional costs would contribute to paying those costs. This is consistent with recommendations in the TRBs Special Report 267 in which it concluded, "federal legislation creating the (TRB's recommended) permit program should specify a quantitative test for the revenue adequacy of the permit fees imposed by states that wish to participate….Fees should at least cover estimated administrative and infrastructure costs for the program… "

Safety is always the issue of greatest concern when truck size and weight issues are considered. Data simply are not available upon which to develop reliable estimates of changes in the number of crashes or fatalities that might result from a change in truck size and weight limits such as the Western Uniformity Scenario. While some LCV operators claim the safety experience of LCVs is better than for the conventional vehicles they operate, these claims cannot be borne out for LCV operations as a whole. States in which LCVs operate have not noted particular safety problems with current LCV operations, but they have no formal processes in place to monitor safety. Since there are many uncertainties about the safety of substantially increased use of LCVs as might occur under the Western Uniformity Scenario, it would be prudent to require such processes before any substantial change in federal truck size and weight limits such as the Western Uniformity Scenario was implemented. In addition to monitoring the on-road safety of LCVs, processes might also be considered to ensure that the vehicles to be used meet some minimum thresholds for stability and control, and that companies operating these vehicles have good safety records and vehicle maintenance programs. One of the criticisms of TRB's recommended permit program was that it would involve conducting experiments with vehicles that were not known to be safe. To the maximum extent possible, assurances should be given that the vehicles to be used are at least as safe as vehicles on the road today and that the companies to be operating those vehicles have excellent safety records.

Nationwide, the Department believes that an appropriate balance has been struck on truck size and weight. Western States included in this scenario all can allow LCVs to operate at weights substantially above the 80,000-pound federal limit on Interstate Highways, and a number of other States can allow axle loads exceeding federal limits under grandfather rights. While the widely varying State laws appear to be inefficient, they are the result of political processes that have attempted to balance economic development concerns with concerns for safety and infrastructure protection. This balance has resulted in somewhat different size and weight limits from State to State, but these differences largely reflect factors unique to each State. The pattern of truck size and weight limits that has evolved over the years may not be optimal by any objective measure, but it does allow for some appropriate regional variation without compromising safety, which is the Department's highest priority.

Many proponents of change in truck size and weight limits point to TRB's recommendations in Special Report 267 as a blueprint for a systematic process to more nearly optimize truck size and weight policy. However, aside from certain segments of the trucking industry and several States interested in truck size and weight increases, strong support for TRB's recommendations has not been evident. The Department has not taken a formal position on the TRB study, in part because it does not favor change in federal truck size and weight policy, but if changes were to be made, the Department believes that the kind of strong monitoring and evaluation that TRB recommends would be essential. Without support for the kind of comprehensive approach to truck size and weight policy and permitting practices recommended by TRB, there would be no mechanism to quickly identify safety or other problems that might arise.

In recent years a number of ad hoc, State-specific exemptions from federal truck size and weight laws have been enacted. For instance, TEA-21 contained special exemptions from federal size and weight limits in four States, Colorado, Louisiana, Maine, and New Hampshire. The Department does not support this kind of piecemeal approach to truck size and weight policy. It makes enforcement and compliance with truck size and weight laws more difficult, it often contributes little to overall productivity, it may have unintended consequences for safety and highway infrastructure, and it reduces the willingness to work for more comprehensive solutions that would have much greater benefits. A regional approach such as the Western Uniformity Scenario could have greater benefits than a series of individual exemptions, but it also could have much more serious adverse consequences unless closely monitored. Unless there were very strong support from State elected officials for a carefully controlled and monitored evaluation of changes in truck size and weight limits such as those in the Western Uniformity Scenario, the risks of adverse impacts from the unmonitored use of LCVs, the divisiveness that might ensue as the current balance in truck size and weight policy is upset, and the further polarization of this very contentious issue would outweigh the benefits that might be realized. Strong support from elected officials of States within the region for a change in truck size and weight limits has not been evident to date, and there is no compelling Federal interest in promoting changes that are not strongly supported by the affected States.

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