Incremental Assignment
增量分配法
Incremental Assignment is a process in which fractions of traffic volumes are assigned in steps. In each step, a fixed proportion of total demand is assigned, based on All-or-Nothing Assignment. After each step, link travel times are recalculated based on link volumes. When there are many increments used, the flows may resemble an equilibrium assignment; however, this method does not yield an equilibrium solution. Consequently, there will be inconsistencies between link volumes and travel times that can lead to errors in evaluation measures. Also, Incremental Assignment is influenced by the order in which volumes for O-D pairs are assigned, raising the possibility of additional bias in the results.
增量分配法中交通量是分次分步加载的。在每一步中，加载一定百分比的交通需求。单次分配是基于全有全无分配法的。每加载一次之后，运行时间要根据当前交通量重新计算。如果加载的次数很多，分配出的结果看起来就像一个平衡分配法；但事实上，这种方法事实上并未产生一个平衡的结果。因此，交通量和运行时间之间的矛盾就会导致评价指标的误差。同时，每次分配的OD量的比例将影响增量分配法的结果，这增加了分配结果的误差。
Capacity Restraint
容量限制法
Capacity Restraint attempts to approximate an equilibrium solution by iterating between all-or-nothing traffic loadings and recalculating link travel times based on a congestion function that reflects link capacity. Unfortunately, this method does not converge and can flip-flop back and forth in the loadings on some links (Sheffi, 1985, p. 113). The capacity restraint method as implemented in some software packages attempts to lessen this problem by smoothing the travel times and by averaging the flows over a set of the last iterations. This method does not converge to an equilibrium solution and has the additional problem that the results are highly dependent on the specific number of iterations run. Performing one more or one less iteration usually changes the results substantially.
容量限制法试图产生一个平衡的结果，它是反复的采用全有全无分配，且根据一个反映路段容量的拥堵函数反复的计算路段运行时间。然而，不幸的是，这种方法不收敛，它会在某些路段上反复加载。为了减小这个问题，某些软件在应用这种方法的时候，在最后一次迭代中滤去时间因素平均分配交通量。
