Unidirectional Pedestrian Flow In An Extended Lattice Gas Model With Variety Velocities Based On Parallel Updating

Pedestrian traffic flow has always been a hot issue that people pay close attention to.In order to reduce pedestrian crowding and stampede accidents,it is necessary to thoroughly study the complex dynamic characteristics and microscopic mechanisms of pedestrian flow.In recent years,many scholars have made some important research results,but many problems remain unresolved.In this paper,we propose a lattice gas model with large maximum velocity with parallel update based on original model.In this expanded lattice gas model,pedestrians can move multiple lattices in a simulation time step.In order to ensure that the pedestrian path is a simple path and more in line with the actual situation,this paper uses a different method.In the simulation,when the drift strength D?27?1,the flow rate with large maximum velocityv_max?29?1 is higher thanv_{ma x}?28?1 and the critical density corresponding to the maximum flow rate is in good agreement with empirical results.With the increase of D,the critical density corresponding to the maximum flow rate always decreases.In the special case D=1,the fundamental diagram exhibits a typical reverse lambda structure as in vehicular flow.The density-flow rate curve has a phase transition at the critical density,the flow rate suddenly decreases and there is the phenomenon of"fast is slow"and"walking and stopping"in pedestrian flow.The improved lattice gas model can better reveal some phenomena and laws of the traffic flow.For the study of mixed pedestrian flow with large maximum velocity,this paper also proposes a new model.In this model,taking into account the higher speed of pedestrians is more aggressive,this pedestrian would prefer to move.For pedestrian conflict with different speeds,the equal probability processing method is used here.By studying the fundamental diagram,we found that when the pedestrian's initial speed distribution is:slow pedestrian?25%?,middle-speed pedestrian?50%?,fast pedestrian?25%?,the average speed shows three different characteristics with the change of density.It is very similar to the measured fundamental diagram of Weidmann.By setting parameter R of the mixing speed ratio,it is found that with the increase of density,the relationship between the parameter R and the flow rate changes from linear to nonlinear.Under high density conditions,with the increase of parameter R,the flow rate increases first and then decreases.Finally,this paper uses the method of mean field analysis to analyze the lattice gas model with variety velocities based on random sequence updating.It is found that when the parameter D is small,the degree of fitting is better.