Singapore has used road pricing since 1975 to manage congestion. The road pricing scheme has evolved from a manual paper permit system during morning peak periods only, to the current electronic system that operates throughout most of the day. The electronic road pricing system uses in-vehicle units with smart cards for payment at gantry toll points. Charges vary based on vehicle type, location, and time of day. The system was expanded over time to include evening peak periods and to establish separate pricing zones. The goal is to reduce congestion and give drivers pricing incentives to choose less congested routes or times of travel. Public transportation is a key alternative to driving under the road pricing system.