Every bus, truck, truck-tractor, and every driven motor vehicle in driveaway-towaway operations shall be equipped with a horn and actuating elements which shall be in such condition as to give an adequate and reliable warning signal.
§393.81 — DOT Regulatory Guidance
Question 1: Do the Federal Motor Carrier Safety Regulations (FMCSRs) specify what type of horn is to be used on a Commercial Motor Vehicle (CMV)? Guidance: No.
Question 2: Are there established criteria in the Federal Motor Carrier Safety Regulations (FMCSRs) to determine the minimum sound level of horns on Commercial Motor Vehicle (CMV)s? Guidance: No.