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36 contributing to national objectives. States would be allowed nario that would be limited to western states already allowing to issue permits for 6-axle tractor-semitrailers with maxi- LCVs. Specifically, the governors asked U.S.DOT to analyze mum weight of 40,823 kg (90,000 lb), and double trailer com- a policy option that would allow 13 western states (Colorado, binations with each trailer up to 10.06 m (33 ft) in length with Idaho, Kansas, Montana, Nebraska, Nevada, North Dakota, seven, eight, or nine axles, and weights governed by the pres- Oklahoma, Oregon, South Dakota, Utah, Washington and ent Federal Bridge Formula. The definition of vehicles eligi- Wyoming) to harmonize LCV weights and dimensions at lev- ble for permitting would be subject to revision over time, but els that meet existing federal axle load limits and the Federal federal review of the performance of the permitting program Bridge Formula and that were consistent with guidelines es- would be permanent and ongoing. tablished by the Western Association of State Highway and The federal government would require states to provide Transportation Officials (WASHTO). The ten impact areas suitable and specified levels of enforcement, user fees, safety, were the same as those used in the CTSW study. These states and bridge management. Enforcement requirements might contain a higher percent of rural roads than urban roads as require states to effectively hold accountable the parties re- compared to the nation as a whole (70). sponsible for placing overweight loads on the highways and The Western Uniformity Scenario analysis included sev- to target repeat offenders. Examples might be "relevant evi- eral substantial improvements to data and methods used in dence" statutes and information systems to facilitate identi- the CTSW study to estimate scenario impacts. These included fying offenders. User fees should be structured to cover both improvements in the truck and rail data, and methods used the administrative and infrastructure costs associated with to analyze pavement, bridge, and safety impacts. One of the the program. Safety requirements should be proposed by biggest improvements was the use of the freight analysis frame- states, reviewed by the Commercial Traffic Effects Institute, work (FAF) commodity-flow data in place of the very limited and approved by the Secretary. Bridge management requires truck-flow data that was available at the time the CTSW study that each state develop a plan for cost-effectively alleviating was undertaken. the constraints on permit vehicles due to deficient bridges. The analysis includes the following vehicles: 5-axle tractor- Federal law should allow operation of LCVs under the pro- semitrailers, twin 8.69-m (28.5-ft) trailers, and five LCVs, in- visions of the federally supervised permit program in a man- cluding Rocky Mountain doubles, turnpike doubles, triples, a ner consistent with other recommendations. 10-axle resource-hauling double, and 8-axle B-trains. The base The committee did not recommend general revision in the case for the analysis was: network of roads to which the various federal dimensional regulations are applicable. In particular, the committee did 9,071 kg (20,000 lb) for a single axle on the Interstate system, not recommend extending federal weight regulation to the 15,422 kg (34,000 lb) for a tandem axle on the Interstate non-interstate portion of the National Highway network, system, which are currently under state regulation for most aspects of Application of the Bridge Formula for other axle groups, up truck operations. to the maximum of 36,287 kg (80,000 lb) for gross vehicle The preceding recommendations call for data collection for weight on the interstate system, systematic monitoring of truck traffic and truck costs to eval- 2.59-m (102-in.) vehicle width on the national network, uate regulatory effectiveness, pilot studies to test new vehicles, 14.65 m (48 ft) minimum semitrailer length in a semitrailer and basic research on the relationship of truck characteristics combination on the National Network, and 8.53-m (28-ft) to highway costs. Specific research topics were: minimum length for trailers in a twin-trailer combination Evaluation of the effectiveness of enforcement of size/ on the national network, Grandfather rights under which certain LCVs are allowed weight regulations, Air quality impacts of changes in truck characteristics, to operate in each scenario state, and Relation of truck performance to crash involvement, LCVs that were permitted by state law but subject to the Risk-based bridge costs, LCV freeze. Freight transportation market research, Costs of mixed automobile and truck traffic arising from The conclusions of the Western Uniformity Scenario analy- nuisance/stress, and sis were similar in some ways to previous study findings. First, New infrastructure development and truck-only facilities. the proposed scenario vehicles and routes varied significantly, but basically allowed more generous gross weight and addi- tional routes compared to the base case. Like previous studies 3.3.5 The Western Uniformity Scenario that examined the potential impacts of changing truck size Following the CTSW study, the Western Governors' Asso- and weight limits, this study found several benefits from al- ciation requested that U.S.DOT analyze an additional sce- lowing more widespread use of LCVs. The benefits included