Usually placed in the front or rear stairwells of a vehicle, a treadle mat sends a signal when stepped on. This signal usually serves one of four functions:
- To prevent the doors from closing on a passenger who is standing in the stairwell..
- To open the rear doors for an exiting passenger when the bus is stopped and the driver has applied power to the doors. The passenger steps down on the mat and the doors open.
- To be used as part of a passenger counting system, either for collecting route statistics or reconciling rider count to fees collected.
- Installed on wheelchair lifts to signal the operator that the wheelchair is in position for lift operation. It can also detect an object on the lift and prevent it from being stowed until cleared.