中文摘要：

车辆性能差异对交通流宏观特性的影响尚未得到充分研究．使用车辆行驶有限状态自动机模型，对由最大速度不同的两种车辆组成的两车道混合交通流进行微观仿真．结果表明混合交通流进入稳态后，相比同质交通流，中低密度区通行能力明显下降，临界密度增加．随慢车比例变化，换道率-密度关系呈现三种模式．在交通流从初始静止状态到稳态运行的过渡过程中，若初始时刻两车道慢车比例不同，随密度不同有三种不同的过渡模式，在低密度区系统迅速过渡到慢车对称分布状态，中密度区系统逐渐过渡到对称状态，但高密度区系统维持在不对称状态．说明慢车对交通流特性有显著影响，混合交通流的过渡过程非常复杂．

英文摘要：

The effects of the differences of vehicles on the characteristics of traffic flow are not very clear. The paper uses a finite-state-machine based driving model to study the characteristics of mixed traffic composed of fast vehicles and slow vehicles. Simulation results show that in a steady state the fluent capacity of mixed traffic decreases significantly and the critical density increases compared with pure fast vehicles traffic. The relationship between the lane changing rate and the density reveals that there appears three patterns when the ratio of slow vehicles varies. In the transitional process, if the composition in each lane is asymmetric initially, there exists three transitional patterns when the density varies, that is, in the low density region, the system turns into symmetric state quickly, in the middle density region, the system progresses to symmetric, and in the high density region, the traffic can not converge to the symmetric state. In conclusion, slow vehicles have significant effects on two-lane traffic, and the transition process of mixed traffic flow is complicated.