It consisted of a series of large glass tubes which held a transportation car inside which were capable of rapid movement. Depending on the destination, the transportation car would move through the pathways on a set path. To change directions, the glass tubes would reorient themselves to connect to another pathway. A central "highway" was present where a spherical chamber had numerous portals to other pathways for the transport car's journey which simply needed to reorient its path to the relevant tube.
The Transformers cartoon
Swoop, Spike Witwicky and Carly made use of the mass transit system to go further into Cybertron while on their search to find the captured Dinobots. Their journey ended when they reached a point where the transit system's glass tube had been destroyed by the collapse of another tube, forcing them to disembark and proceed on foot.
Grimlock and the other Dinobots later made use of the system to fly themselves from the Cybertonium Pits to the surface. As the Dinobots were capable of robot-mode flight, no car was required.