Commute Congestion Pricing Strategy Of A Bottleneck In Corridor

Car usage increases rapidly while road capacity usually couldn’t accommodate such a heavy traffic. Especially, in morning peak period, commuters frequently confront congestion at corridors connecting CBD and satellite cities. Transportation authority may either adopt congestion pricing policy or construct the mass transit system. Both of strategies aim to encourage transit usage and shift commuters from private cars to the transit system. The public, however, regards congestion toll as coercive and suspects the purpose of using collected tolls. Much work on static models has focused on single O-D pair bottleneck congestion pricing with a single mode of automobile-highway system. Besides, previous studies have applied the Optimal Control Theory to construct dynamic models on single bottleneck highway congestion pricing. On another line of research, mass transportation system scheduling, dispatching problems have been commonly analyzed by satisfying passenger demands from the perspective of the operator.This study considers the competitive transit line which parallels the highway bottleneck and serves the same corridor. Then, this study applies the Optimal Control Theory to formulate a dynamic traffic assignment model by minimizing commuters’time-dependent travel cost. If there exists a set of solution in the Optimal Control Problem (OCP), the first-order necessary conditions should be sufficient to this OCP. Meanwhile, the multiplier analysis reveals the system marginal cost fluctuation caused by commuters’dynamic mode choice decisions. Furthermore, an optimal time-varying toll is derived and an iterative algorithm is proposed for solving this OCP which shows the two-mode assignment evolutions in each time interval of the study period. The study further proposes a strategy that transportation authority collects the toll revenue from car users to subsidize transit operating cost so as to increase the frequency of transit dispatching runs and shift car trips to transit trips. As a result, an optimal subsidy, which minimizes system equilibrium cost could be determined.Practically, toll revenue could be used on subsidizing transit or supporting the facilities of Electronic Road Pricing (ERP). In the case study, we determine an optimal ratio of49.3%of toll revenue to subsidize transit operating cost, while use the remainder of toll revenue to maintain the ERP’s facilities. Due to the subsidy, transit dispatching headway could be shortened to4.8minutes from the initial6.3minutes. Compared with the headway of5-7minutes of Chengdu Metro System during the peak period, the optimal headway of4.8minutes obtained in our case study is reasonable. Finally, transportation authority could also release a latent capacity which is considered to be reserved for the adaptive management of high-level congestion.