User Equilibrium (UE)
用户平衡法
User Equilibrium uses an iterative process to achieve a convergent solution, in which no travelers can improve their travel times by shifting routes. In each iteration, network link flows are computed, which incorporate link capacity restraint effects and flow-dependent travel times. The formulation of the UE problem as a mathematical program, and the Frank-Wolf solution method employed in transcad, are described in Technical Notes on Traffic Assignment.
用户平衡法采用一个反复的过程来得到一个平衡解，在这种方法中旅行者不能通过改变路线来改变旅行时间。在每一次迭代中，路段交通量都会重新计算，计算中同时考虑了路段通行能力和运行时间。用户平衡法可以用精确的数学程序表达，transcad采用的是Frank-Wolf法，这种方法详见“交通分配技术要点”。
Stochastic User Equilibrium (SUE)
随机用户平衡法
Stochastic User Equilibrium is a generalization of user equilibrium that assumes travelers do not have perfect information concerning network attributes and/or they perceive travel costs in different ways. SUE assignments produce more realistic results than the deterministic UE model, because SUE permits use of less attractive as well as the most-attractive routes. Less-attractive routes will have lower utilization, but will not have zero flow as they do under UE. SUE is computed in transcad using the Method of Successive Averages (MSA), the only known convergent method (Sheffi and Powell, 1982; Sheffi, 1985). Due to the nature of this method, a large number of iterations should be used. [Page]
随机用户平衡法是一个广义的用户平衡法，它假设道路使用者不能获得精确的路网信息，而且/或者不会意识到不同路径的运输成本的差别。相比用户平衡法，随机用户平衡法会产生一个更现实的结果，因为他同时允许最优路径和较差路径。较差路线分配量较少，但是不会像用户平衡性中那样出现零交通量。对于随机用户平衡模型，transcad中采用的是目前所知唯一收敛的方法：连续平均法。由于这种方法本身的特性，它需要进行大量的迭代
