Summary: Under state regulations that predate federal size and weight laws, 20 states allow limited operation of longer and heavier trucks, generally referred to as longer combination vehicles. The safety and the expanded use of these trucks have been hotly debated. GAO found that with few exceptions, states have not compiled data on the safety and the operation of these trucks on the western highways and eastern turnpikes where they are now permitted. As a result, many of these states lack the information needed to spot problems that might arise from increases in traffic density or from the use of the vehicles by less-experienced drivers and companies. Only three states do special inspections of longer combination truck equipment. Other states rely largely on trucking companies and drivers to ensure that equipment meets state requirements and is in safe operating condition. Longer combination trucks are included in roadside inspections but have not been singled out for special attention. The states allowing longer combination trucks have widely differing controls and levels of enforcement. Many states have yet to adopt rules on drivers' experience and safety records. Factors that may account for the low accident rate among longer combination trucks include the low traffic density on many routes they commonly travel and the operation of triple trailers mainly by large companies with good safety records.
