The invention belongs to the technical field of rail transit and specifically relates to a rail transit system. The invention aims at solving the stability problem of a train during steep slope rail running in the prior art. The invention provides a track beam with a tractor running board and a running assistant tractor running on the tractor running board; the running assistant tractor further comprises a first traction mechanism and a second traction mechanism which are correspondingly used for fixing a traction cable and a pulled train bogie; and through the running assistant tractor, a traction force of the traction cable can be transmitted to the pulled train bogie. As the track beam is arranged on a steep slope, an up train and a down train during running are connected with each other through coordination between the running assistant tractor and the traction cable; and therefore, the stability of the pulled train during steep slope running can be guaranteed, the pulled train issafe and reliable, energy is saved and consumption is reduced.