What must trailers or semi-trailers have to prevent them from becoming free rolling when disengaged from a towing vehicle?

Trailers and semi-trailers must be equipped with proper brakes to prevent them from becoming free rolling when they are disengaged from a towing vehicle. This is critical for safety reasons. If a trailer becomes detached while on the road, it can potentially roll away unchecked, posing a significant danger to other road users and causing accidents.

Having proper braking systems ensures that the trailer can be controlled even when it is not attached to a towing vehicle. This includes features like wheel brakes that are operable when needed, securing the trailer in place. Braking systems are often mandated by law for larger trailers and semi-trailers, especially in commercial transport scenarios where safety regulations are stringent.

While reflective tape, GPS tracking, and audio alerts serve various safety and visibility purposes, they do not prevent the trailer from becoming free rolling. Reflective tape helps increase visibility, especially at night; GPS tracking assists in monitoring the location of the trailer; and audio alerts may provide warnings for different situations. However, these features do not directly address the fundamental requirement for a trailer's stability and safety when not hitched to the towing vehicle.