Congestion pricing in an environmental perspective - A simulation of toll rates differentiated by time of day in Oslo

Toll rates differentiated by time of day can be considered as method of congestion pricing. While relieving congestion this should also be a cost effective way to reduce air pollution from road traffic. A transport model is used to simulate two alternatives with differentiated toll rates. Two additional alternatives comes from combining congestion pricing with improved level of service in public transport. The results show 23-28 per cent reduction in fuel consumption for traffic in the central area of Oslo in peak periods. At present the concentration of air pollutants in this area frequently exceeds recommended maximum levels in peak periods. The cost effectiveness stems from the fact that reduced road traffic improves driving speeds and thus causes reduction in costs for the remaining traffic.