Modelling the effects of road pricing on traffic in Singapore

With increasing worldwide interest in the application of urban road pricing, the experience of Singapore can be very useful. Under the Singapore Electronic Road Pricing (ERP) system, charges for entering the city centre and using some expressways vary by time of day and are being periodically revised in order to maintain traffic speeds within the desirable bands. Traffic response to these revisions shows that demand elasticity with respect to pricing is higher for cars than for other vehicles and higher for expressways than for the city centre cordon. It is also lower in the morning peak and higher in the afternoon. A discrete choice based model of motorist response to pricing is proposed for a single toll point with peak period variable pricing. The choices considered include the time interval of travel and re-routing to avoid the toll. The model was calibrated for one expressway and two arterial roads using only traffic volume data collected before and after ERP introduction. The model reflected well the peak spreading effect of variable road pricing and the penalties for rescheduling and re-routing of trips. In general, the Singapore experience suggests that variable pricing is an effective method of controlling congestion.