A study conducted by the Insurance Institute for Highway Safety (IIHS) released in December of 2016 shows that tractor-trailers with any out-of-service violation are 362 percent more likely to be involved in a crash. This is especially important because some trucking companies and shippers continue to push Congress to approve longer and heavier tractor-trailers, which have been found to have more defects than today’s 80,000-pound, single-trailer trucks.
The U.S. Department of Transportation (USDOT) delivered its Final Report to Congress in April of 2016 that recommended against any increases in current truck size and weight laws and regulations. In the study, USDOT found that double-trailer configurations have 58 percent higher out-of-service violation rates than single-trailer trucks. The report also found that trucks weighing over the current 80,000-pound gross vehicle weight limit had higher overall out-of-service violation rates and 18 percent higher brake violation rates compared to those at or below the current 80,000-pound limit.
The IIHS study can be found here: http://www.iihs.org/frontend/iihs/documents/masterfiledocs.ashx?id=2128