Impacts of bus holding strategy on the performance and pollutant emissions of a two-lane mixed traffic system

This paper investigates the impacts of a bus holding strategy on the mutual interference between buses and passenger cars in a non-dedicated bus route,as well as the impacts on the characteristics of pollutant emissions of passenger cars.The dynamic behaviors of these two types of vehicles are described using cellular automata(CA)models under open boundary conditions.Numerical simulations are carried out to obtain the phase diagrams of the bus system and the trajectories of buses and passenger cars before and after the implementation of the bus holding strategy under different probabilities of passenger cars entering a two-lane mixed traffic system.Then,we analyze the flow rate,satisfaction rate,and pollutant emission rates of passenger cars together with the performance of a mixed traffic system.The results show that the bus holding strategy can effectively alleviate bus bunching,whereas it has no significant impact on the flow rate and pollutant emission rates of passenger cars;the flow rate,satisfaction rate,and pollutant emission rates of passenger cars for either the traffic system or for each lane are influenced by the bus departure interval and the number of passengers arriving at bus stops.

Improving service regularity for high-frequency bus services with rescheduling and bus holding

In high-frequency bus services,maintaining the service regularity is a critical issue.The service regularity is directly related to the excessive waiting times(EWT) of passengers at bus stops.In a regular service,the EWT is minimized resulting in even headways between consecutive buses of the same line.In this study,we propose the combined use of rescheduling and bus holding to improve passengers’ excessive waiting times.We model the dynamic rescheduling and bus holding problem as an integer nonlinear program(INLP) and we prove its NP-hardness.Our model considers the constraints of the original timetable e an issue that is usually neglected from most dynamic control methods.Given the NP-hardness of our mathematical program,we introduce a problem-specific heuristic to explore efficiently the solution space.The convergence rate of the proposed heuristic is tested against other solution methods,including simulated annealing with linear cooling,hill climbing and branch and bound with multi-start sequential quadratic programming.In addition,simulations with the use of actual operational data from a major bus operator in Asia Pacific demonstrate an up to 35% potential EWT improvement for a minor increase of 6% to the travel times of onboard passengers.