Automatic toll collection is a wireless system to automatically collect the usage fee or toll charged to vehicles using toll roads, HOV lanes, toll bridges, and toll tunnels. It is a faster alternative which is replacing toll booths, where vehicles must stop and the driver manually pays the toll with cash or a card. In most systems, vehicles using the system are equipped with an automated radio transponder device. When the vehicle passes a roadside toll reader device, a radio signal from the reader triggers the transponder, which transmits back an identifying number that registers the vehicle's use of the road, and an electronic payment system charges the user the toll. A major advantage is a driver does not have to stop, reducing traffic delays. Electronic tolling is cheaper than a staffed toll booth, reducing transaction costs for government or private road owners. The ease of varying the amount of the toll makes it easy to implement road congestion pricing, including for high-occupancy lanes, toll lanes that bypass congestion, and city-wide congestion charges. The payment system usually requires users to sign up in advance and load money into a declining-balance account, which is debited each time they pass a toll point.