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BUS SERVICE OPTIMIZATION AND CAR PRICING POLICIES TO SAVE FUEL IN URBAN AREAS

The effectiveness of optimal bus policy for dealing with fuel consumption in urban areas under different hypotheses of car pricing is investigated. The transport system of autos and buses is modelled as set of modes in equilibrium where bus service is provided with the objective of maximizing fuel savings over the whole of the road network and where car pricing is exogenously imposed by local authority. Results of a case study show that policies based on frequency, fare, and bus size alone have negligible effectiveness unless they are supported by car pricing measures. Also, the strong sensitivity of optimal bus operating parameters with respect to the time-to-fare elasticity ratio of demand is highlighted.

Bus service optimisation with fuel saving objective and various financial constraints

A model for optimal bus service in urban areas is presented. Following the recent increasing environmental concerns the model takes, as objective function, the total (bus and car modes) reduction of fuel consumption. The optimal service level, price and bus size are determined subject to the operator financial constraint and the capacity constraint. Two formulations of the financial constraint are considered: subsidy as fraction of costs and subsidy as fixed amount. Bus-km and average revenue per passenger carried are used as proxies for service level and price, respectively. Bus demand varies with the generalised cost of bus travel according to a constant elasticity. Transfers of passengers from car to bus are a given fraction of the demand newly attracted from bus. Model solution requires only one algebraic equation to be solved for one of the service variables, the remaining being provided in closed form. A selection of the results for a case study shows the variations at optimum of bus service variables with the operating parameters. The conditions under which bus policies based on service level and price are effective to save fuel and the different policy implications deriving from the two financial constraint formulations are highlighted.

Stochastic User Equilibrium and Analysis of Users’ Benefits

When random utility models are used to represent the choice of the route alternatives, the benefits accruing to the users as a consequence of an intervention on the network can be estimated rigorously on the basis of the expectation of the compensating variation. A rigorous disaggregate analysis which considers shares of shifters and non-shifters and attributes benefits to them can be carried out based on transition probabilities and associated conditional expectations of the compensating variation. The chapter extends the results available in the literature on the computation of transition probabilities and conditional welfare measures to cases of imperfect before-after correlation of the random terms and changing choice set. The theoretical results are illustrated with applications to the town bypass case and the Dupuit-Nguyen network.