在开放边界条件下，采用无后退有偏随机走动者格子气模型对十字路口的行人疏散动力学进行了计算和模拟。结果显示，当纬向边界行人密度保持恒定时，经向和纬向通道行人堵塞现象的出现取决于不同的经向边界行人密度；当纬向通道宽度保持不变时，发生堵塞的临界边界行人密度取决于不同的经向通道宽度，纬向和经向的行人堵塞动力学演变具有不同的特征。模拟结果对于疏散通道的设计具有指导意义。

Under the condition of open boundary, pedestrian evacuation dynamics in crossing exit is simulated through the lattice-gas model of biased random walkers without back step. Attention is concentrated on the mean velocity of pedestrian flow while simulating and analyzing, for it is the key factor to study the fundamental rules between the boundary density and width of route and to estimate jam transition during evacuation. In the simulation, the jamming transitions are observed at the longitudinal route or latitudinal route or both routes when the longitudinal pedestrian boundary density increases under the constant values of latitudinal pedestrian boundary density. Fixing the width of latitudinal route, a series of critical boundary densities which indicate the jamming transition are gained under different values of width of longitudinal route. By plotting the relation in certain coordinate system, the phase diagram can be concluded, which can express the jamming transition clearly. It is found in the phase diagram that the longitudinal and latitudinal dynamical phase transitions present different patterns. In the end, it should be pointed that the simulation results in this paper will be helpful for the design of evacuation routes.