What is "balloon loop"

n. A looped section of track that allows a rail vehicle or train to reverse direction without having to shunt or even stop.

A balloon loop or turning loop allows a rail vehicle or train to reverse direction without having to shunt or even stop. Balloon loops can be useful for passenger trains and unit freight trains such as coal trains.

Balloon loops are common on tram or streetcar systems. Many streetcar and tram systems use single-ended vehicles that have doors on only one side and must be turned at each end of the route, or else haul trailer cars with no driver's cabin in the rear car.