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Truck Combinations Used Along and Across the Western Border

The complex TS&W regulations applicable in the western border region allow and lead to the use of many different truck configurations along and across the western border. Several are unique to the region. Small trucks of four or less axles dominate the truck fleets in western border States (90 percent in North Dakota; 80 percent in Washington, Idaho and Minnesota; 75 percent in Montana). For the western border fleet of trucks that has five or more axles:

Tractor-semitrailer combinations are most common--7 of 10 in Washington and Idaho, 8 of 10 in Montana, and 9 of 10 in North Dakota and Minnesota (86.6 percent nationwide). The tractor-semitrailer fleet in the western border States is complicated. It consists of conventional five-axle units, five-axle units with a split tandem axle on the semitrailer, six- axle tractor-semitrailers (some with wide-base rather than dual tires on the semitrailer), seven-axle tractor-semitrailers (with a lift axle on the tractor), eight-axle tractor- semitrailers (with lift axles on both the tractor and semitrailer).

Truck-trailer combinations are the next most common--1 of 5 in Washington and Idaho; and 1 of 10 in Montana, North Dakota and Minnesota (7.5 percent nationwide). These include a variety of truck-trailer combinations with five, six, seven and eight-axles.

Tractor-double trailer combinations follow--1.5 of 10 in Washington and Idaho, 1 of 10 in Montana, 1 of 20 in North Dakota, and 1 of 100 in Minnesota (5.9 percent nationwide). These include a variety of double-trailer A-trains, including western doubles and Rocky Mountain doubles, with from five to nine-axles; a few seven- or eight-axle double-trailer C-trains; and eight-axle double-trailer B-trains. The ISTEA freeze limits the cargo- carrying length of these units on the NN to 68 feet in Washington, 95 feet in Idaho, 93 feet in Montana, and 103 feet in North Dakota.

Triple-trailer combinations are either non-existent as in Washington and Minnesota or infrequent (less than 0.1 percent nationwide).

Containers are moved by truck between Seattle and Vancouver, often using a variety of vehicles specially-designed to comply with the combined effects of Bridge Formula B, the 105,500-pound Washington State GVW cap, Washington trailer length limits, and Canadian RTAC regulations.

Because of these varying TS&W regulations, depending on the jurisdictions being crossed and the highway classes used, trucks crossing both the international and State borders in the western region may: (1) be stretched or contracted using adjustable drawbars; (2) have axles raised, lowered, or re-positioned; (3) have fifth wheels re-positioned; (4) have tires removed or added; or (5) have loads modified or shifted.

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