The Sheep and Bottleneck Realities, Congestion Charging As Second Best Pricing Policy
A Lauer, Ministere de l'Equipement, FR
The traditional economical approach to road pricing is based on the confrontation between a demand for transport capacity and a supply of transport capacity. The equilibrium point is estimated by taking into account the elasticities of the demand and supply functions. Thus the logic of this approach appears to be based on continuity.
In the contrary the alternative approach proposed in the paper is based on discontinuity and ruptures. Congestion with the bottleneck phenomenon is modelled as a discontinuity.
Demand with the sheep-like behaviour can be modelled in a similar way.
In certain circumstances this approach makes it easy to estimate the main calibration parameters of a road pricing policy. A case study will illustrate it. It is the problem of optimising a road pricing strategy for the urban area of Lyon.
The case problem originated with the opening of a new section of the urban motorway system of Lyon. This section was operated as a toll motorway whereas the rest of the network was toll free. The global strategy was obviously incoherent. It was put in full light by a vigorous reaction of the citizens. The municipality did not want to abandon the financial resource of tolling. Several studies were launched to explore the possible alternative policies. Among them was the demand for defining an 'optimal' road pricing policy.
Two main strategies were considered: congestion charging and 'flat pricing'. They were optimised individually using the above mentioned approach. The main results will be presented in the paper. The two policies were then compared in regard to a set of reasonable assessment criteria. The main of them are: generated income, social benefit, 'fairness'.
The global result is that congestion charging appeared to be the second best strategy. The transferability of this finding to other urban contexts will be discussed.
Association for European Transport