Pursuant to a congressional request, GAO reviewed the safety of longer combination vehicles (LCV), focusing on the: (1) current extent of LCV use; (2) results of LCV safety studies; and (3) major operational characteristics that affect LCV safety. GAO found that: (1) 20 states allow LCV operation, but they have different restrictions on the types of LCV allowed, the routes on which they can operate, their length, and their weight; (2) LCV safety studies have reached very different conclusions, with some studies finding that multiple-trailer trucks are less likely to be involved in accidents than single-trailer trucks, while other research indicates that multiple-trailer trucks are more likely to be involved in accidents; (3) a lack of adequate truck data and different study methodologies contributed to different research conclusions; (4) LCV safety tests indicate that multiple trailers are more apt to sway than single trailers, require a wider turn path, and are more likely to travel out of their lane; (5) LCV operational characteristics are affected by LCV type, the driver, load distribution, equipment used, and road conditions; and (6) projections of an increase in traffic density and a shortage of experienced truck drivers could impact future LCV safety. | Truck Safety by U U S Government Accountability Office (G, Paperback | Indigo Chapters