Effects of alternative road pricing systems on network performance

Four road pricing systems, with charges based on cordons crossed, distance travelled, time spent travelling and time spent in congestion, have been te sted using the congested assignment network model SATURN and its elastic as signment demand response routine, SATEASY. All tests have been based on a S ATURN application of the city of Cambridge, with charges imposed inside an appropriate ring of bypasses. While initial results showed that congestion pricing achieved the greatest increase in average speed in the charged area , later analysis cast doubt on-its superiority. Congestion pricing is able to distinguish more effectively the extent to which different types of jour ney contribute to congestion and achieves given reductions in travel at low er levels of charge. However, it is much less effective in reducing distanc e travelled and, by encouraging use of minor roads, may achieve far smaller environmental benefits. Time-based pricing performs better than the other systems on most indicators. Generally, the results suggest that when rerout ing effects are included in the predictive modelling process the benefits o f road pricing may be significantly smaller than previously expected. (C) 2 000 Elsevier Science Ltd. All rights reserved.