Which of the following administrations is NOT under the U.S. Department of Transportation and directly related to trucking?

The Federal Transit Administration (FTA) is focused on public transportation systems and is not directly involved with trucking regulations or oversight. The FTA's primary role is to provide financial and technical assistance to local public transit systems and develop policies that improve and innovate public transit infrastructure.

In contrast, the other administrations mentioned are directly related to trucking and commercial vehicle regulation. The Federal Highway Administration (FHWA) oversees national highways and infrastructure, impacting trucking routes and safety; the National Highway Traffic Safety Administration (NHTSA) deals with vehicle safety standards and regulations, affecting trucks as part of the broader vehicle safety landscape; and the Federal Motor Carrier Safety Administration (FMCSA) specifically regulates the trucking industry, focusing on safety and operational efficiency of commercial motor vehicles. Hence, the FTA stands apart from these trucking-related entities, supporting public transit rather than the commercial trucking industry.