Tradable Credit Scheme to Control Bottleneck Queue Length

This paper proposes to use tradable credits to control the maximum queue length at a bottleneck. Given a queue length threshold specified by the traffic authority, the authors designed a tradable credit scheme to maintain the queue length of the bottleneck to be less than the threshold for homogenous travelers. The scheme was compared against a multistep tolling scheme under demand uncertainty. The authors then studied the capability of the tradable credit scheme in the presence of two types of user heterogeneity: proportional heterogeneity and heterogeneity in unit schedule penalty associated with late arrival (γ heterogeneity). It was found that the proposed scheme could successfully maintain the queue length under proportional heterogeneity, but not necessarily under γ heterogeneity. However, if the distribution of γ heterogeneity were known in advance, the scheme could be modified to ensure success in controlling queue length.