The Impact Of Bus Service Levels And Driving Restriction Policy On The Stability Domain And Dynamical Characteristics

With the rapid economic development, Chinese population and car ownership are increasing year by years, resulting in traffic demand exceeds supply in many cities. To solve this problem, lots of scholars have proposed congestion charges, parking fees, transportation rationing system and the driving restriction policy. Among these policies, the driving restriction policy can be more quickly reduce traffic demand through compulsive means, to relieve urban traffic congestion. Short-term driving restriction policy can quickly reduce traffic demand. When the long-term driving restriction policy is implemented, the cars’ growth rate slows down, but traffic and environmental problems don’t be solved fundamentally, even leading to more traffic congestion and pollution problems. Compared with cars, buses have many advantages, such as large volume, safety, lower cost, low energy consumption, less pollution and so on. Thus, in this paper we studied how to improve bus service levels, thereby eliminating the negative impact of the long-term driving restriction policy on transport network state. Namely, dynamic traffic assignment model and system characteristics considering transit development and driving restriction policy, dynamic traffic assignment model and system characteristics considering bus signal priority and driving restriction policy. The main contents are as follows:Firstly, we aimed at studying the impact of improving bus and driving restriction policy on the network status.And then a period-to-period dynamic assignment model was proposed to analyze these effects. In this model, dynamic evolution process includes mode selection process and path selection process. According to travelers’ actual behavior, the dynamic evolution of transport network is divided three cases. Namely, case Ⅰ:no buses; Case Ⅱ:with buses, the mode selection and path selection is updated simultaneously; CaseⅢ:buses exist, and the path selection is updated for m periods, mode selection is updated each period. According to nonlinear theory, the impacts of bus frequency and rationing ration on stability of the system equilibrium and traffic patterns were analyzed in three cases. It was found that offering bus or increasing rationing ratio is helpful to increas the stability region of the system equilibrium. Increasing rationing ratio can reduce the system cost, bringing a positive impact to the system. However, driving restriction policy make more and more travelers being forced to travel by bus, leading to bus crowding, convenience deteriorated, bus cost increased, bus service level decreased. Increasing bus frequency can reduce these negative impacts, causing by driving restriction policy.Next, we considered the impact of the bus signal priority and driving restriction policy on the network status. Bus and car’s delay models are builded up respective under the Green Extension and Red Truncation Strategy, considering the difference of bus and car delay in the bus signal priority intersection. Based on this model, we established the dynamic assignment model considering bus signal priority and driving restriction policy. The impacts of bus signal priority strategy, maximum extension time in the green extension and red truncation strategy, bus frequency and rationing ratio on the road network were analyzed. The results showed that in the priority phase increasing bus frequency or maximum extension time can make the system gradually transiting from an equilibrium state to an unbalance state. When the system reaches equilibrium state, increasing bus frequency can attract more travelers to actively choose to travel by bus, which bring more benefits in green extension strategy. Under the green extension and red truncation strategy, increasing maximum extension time will increase traffic in the priority direction and decrease traffic in non-priority direction; And with the maximum extension time increasing, bus and car’ cost will increase, but because the overall road network flow is reduced, thus reducing the system cost. And car’s cost increases even more sharply, thus highlighting the advantages of bus, leading more travelers tending to choose to travel by bus, bringing a positive impact.