Optimal Design of Bus Routes for Different Vehicle Types Considering Various Driving Regimes and Environmental Factors

Abstract

As a major part of public transportation systems, bus transit has been regarded as an effective mode to alleviate traffic congestion and solve vehicle emission problems. The performance of a bus transit system depends largely on the design of bus stop locations. This research proposes a multi-period continuum model (peak and off-peak hours) to optimize the design of a bus route for four different vehicle types (i.e., supercharge bus, compressed natural gas (CNG) bus, lithium-ion battery bus, and diesel bus) considering driving regimes and pollutant cost. Inter-stop driving regimes—acceleration, cruising, coasting, and deceleration—are explicitly introduced into the optimization to determine whether and how the coasting regime should be undertaken in the tradeoff between commercial speed of vehicles and operating costs. The cost effectiveness of each alternative has been investigated in a life cycle and compared with respect to different vehicle types. The method has been applied to the real-world bus route no. 7 in Yaan City (China). The results of numerical experiments show that through optimization the total system cost can be reduced by more than 50%. The results of the continuum model are validated by comparison with the discretized results, and the outcomes are similar (with error less than 3%). Finally the life-cycle cost of the four vehicle types is analyzed, and the results indicate that, because of high purchase prices, it is difficult for clean-energy buses to outperform conventional buses in a life cycle (normally eight years), unless subsidies are provided.