Operation of Long Semitrailers in the United States

The regulation and use of long semitrailers (57 to 60 ft) in the United States are discussed. Industrial information was obtained from interviewing 42 state and federal regulatory and compliance officials, vehicle manufacturers, motor carriers, and shippers. Field data from a June 2002 investigation of long semitrailer use on an Interstate highway section in Texas are presented. No known significant literature exists on the topic under discussion. The research found that long semitrailers operate, either regularly or under permit, in 19 states. They are principally used by a few large private and for-hire carriers, transporting mainly tissue paper, empty cans, hay, cotton, empty storage container drums, household goods, snack foods, and general freight. The extent of their operation is largely unknown or unclear to many of those involved with truck size and weight research and development activities, highway planners and designers, and industry participants. The following are addressed: (a) issues about long semitrailer operation in the United States and the growth potential of these vehicles relative to the TRB Special Report 267 proposal to allow wide-scale use of six-axle tractor-semitrailers at a gross vehicle weight of 90,000 Ib; (b) background on using long semitrailers; (c) operational issues associated with long semitrailers; (d) typical dimensional characteristics and cubic payloads of long semitrailers compared with standard semitrailers; (e) field data on the use of long semitrailers in Texas; and (f) regulations, permit requirements, and allowable geographic scope of operation for long semitrailers.