Cellular automaton model for mixed traffic flow with motorcycles

A single-lane cellular automaton model is proposed to simulate mixed traffic with motorcycles. By performing numerical simulations under the periodic boundary condition, some density-flow relations and the "lane-changing" behavior of motorcycles are investigated in detail. It is found that the maximum car flow decreases because of the "lane-changing" behavior of motorcycles. The maximum total flow increases first and then decreases with increasing motorcycle density. Moreover, the transition of the total flow from the free flow to the congested flow is smooth in this model. The "lane-changing" rate of motorcycles will decrease to zero finally with the increase of the car density. But its evolutionary trend is considerably complex. Another interesting fact is that, with the increase of the motorcycle density, the "lane-changing" rate increases first and decreases later. This phenomenon is very similar to the findings in other papers on multi-lane car flows. The "lane-changing" is almost of no use in increasing the flow of motorcycles as the motorcycle density is small. But it distinctly causes the increase in the flow of motorcycles when the motorcycle density is sufficiently large, and in this density regime, the flow of motorcycles gradually decreases to the one given with the Nagel-Schreckenberg model for motorcycles with the increase of the car density. The simulation results indicate that it is necessary to set a barrier or a lane for separating the motorcycle flow from the car flow except in some special density regime. (C) 2007 Elsevier B.V. All rights reserved.