Alternative Tradable Credit Scheme on General Transportation Network

This paper designs and analyzes an alternative tradable travel credit scheme on general transportation network for managing travelers’route choice behaviors.The scheme is a kind of charging and rewarding mechanism,which provides an attempt to urge travelers to plan their travel routes reasonably so that excessive traffic congestion can be mitigated.Mobility credits are imposed on those travelers who use high congested routes,while rewarded credits are given to those travelers who switch to the low congested routes.A free tradable market is created such that the travelers paying credits can purchase them from those earning them from the rewarding travel route choices.When the total amount of credits earned is equal to the amount of credits consumed,transfer of wealth can only take place among the travelers and hence overcome the inequity problem of congestion pricing.On the general transportation network,the type of tradable credit schemes can be formulated as a mathematical programming with equilibrium constraint（MPEC）model.Based on the model,a credit charging mechanism is obtained under the system optimum and Pareto-improving system optimum conditions.

A modern congestion pricing policy for urban traffic:subsidy plus toll

Congestion pricing is seen as an effective policy to address traffic congestion. In such policies where money, people and authorities are involved, the success generally hinges upon two factors： equity （being fair） and accept- ability （to both people and authorities）. The primary con- cern is the equity, for which ＂tradable credit scheme （TCS）＂ has been introduced and extensively studied in the literature. Nevertheless, due to the com- plexity of the trading schemes, the TCS has yet to find any foot in the real world. To this end, a novel idea of rewarding has substituted the trading component to be known as toll-and-subsidy scheme （TSS）. The idea is to charge the drivers on some roads （toll） while rewarding them to use other alternative--and perhaps underutilized-- roads （subsidy）. The research of the TSS is in its infancy stage. The problem to be tackled in this study is as follows： Given a set of roads constituting a cordon line around the central business district （CBD） or across a screen line, how much toll or subsidy should be assigned to each road？ The problem is first transformed into a capacitated traffic assignment problem. We employ a solution method based on augmenting the travel time of roads up to the level at which the traffic volumes do not exceed some target rates. A real dataset from the city of Winnipeg, Canada, is used as a pilot study. We then discuss policy-related applications of the TSS. It is proved in the literature that one can obtainoptimal TSSs for various objectives and considerations. To this end, the non-negativity of the toll values is relaxed which results in a valid toll set. Nevertheless, the compu- tational time is found to be of highest significance. Our method differs in the fact that the traffic volumes are bounded from the above and it is quite affordable. The main contribution is first to highlight the concept of sub- sidy along with traditional thought of merely toll. Second is to interpret the Lagrangian values of the capacity con- straints as the values of the toll/subsidy.