The Simulation And Anaysis Of Bus Transit Based On The Cellular Automata Model

Priority of public transportation is among the best choices of addressing the traffic congestion. The research on buse transit in urban mixed traffic flow has been a focus in traffic field, which has the positive effect on enhancing the service level of public transportation and improving the urban traffic condition.Based on traffic flow cellular automata model (CA), the thesis simulated bus transit in urban mixed traffic flow with VB6.0. The main contents are as follows:1) Based on the CA model, rules were constituted to realize the activities of buses and passengers at bus stop. Bus delays on and out of the bus stop were got by varying the values of bus stop capacity and passengers arriving at bus stop. Then the relationship of bus arriving at bus stop and bus capacity to bus delay can be analyzed.2) By analyzing the classical two-lane CA model STCA and its derivative model STCA-â… ,STCA-â…¡,ASTCA, the appropriate lane changing rules for urban mixed traffic flow considering the effect of buses were put forward. The relationships of average velocity and flux to density were showed by simulating the mixed flow which the bus-car ratio took values ranging from 0 to 1.By analyzing the statistical data, the conclusions are as follows:1) When buses arriving at bus stop with several of them at the same time, the way of increasing the bus capacity cannot improve the situation of bus delay radically and it makes the delay on the bus stop longer.2) Bus arriving character at bus stop has determinant effect on bus delay.3) Buses have negative effect to the velocity and flux of traffic flow.4) When the density takes value ranging from 0.2 to 0.6, the traffic flow is obviously affected by the random slow effect and vehicles with low speeds, and some effective optimized methods can be employed to improve traffic condition.The research is instructive to improve the transportation effectiveness of bus route and stop. Meanwhile, it has proved the necessity to set up the bus lane on the roads conforming to the level of density and lane number.