Regulations to promote safe operation of large trucks and buses have been part of U.S. Federal policy since the 1930s. Most recently, the Motor Carrier Safety Improvement Act of 1999 assigned this regulatory responsibility to the Federal Motor Carrier Safety Administration (FMCSA) in the U.S. Department of Transportation. Most of the large body of research on occupational road safety in the U.S. has focused on identifying and mitigating road risk for operators of large trucks and buses through behavioral, engineering, and management interventions.