Rubber-tyred tram

The Translohr system operates as a guided vehicle at all times, while with the Bombardier system the vehicles can be driven independently as requirements dictate, such as journeys to the depot. Consequently, the Bombardier vehicles are legally considered buses, and must bear rear-view mirrors, lights and number plates, and are controlled with steering wheels and pedals like ordinary buses, though the steering wheel is not used when following the guidance rail. On the other hand, Translohr vehicles operate like standard trams and cannot move without guidance, so they are not classified as buses and are not equipped with number plates. The ART system can be diverted by virtual track by the driver using a conventional steering wheel.

These systems are intended to offer a more tram or light rail-like experience than a regular guided bus, and offer some advantages over steel-wheeled trams, such as the ability to climb steeper gradients (up to 13%), and quieter running around corners. The infrastructure installation can be less complicated than the installation of a complete tram line in an existing street. These systems have been likened to the tram equivalent of rubber-tyred metros, and they are also less efficient than steel-wheeled light rail vehicles. There is no evidence to prove the superiority of either guidance system. Both Bombardier and Translohr have had derailments during operation.