The upper level is a car ownership model, in which objective function is to maximize the total of zonal car ownerships and the constraint is traffic environment load on a link should not exceed the pre-decided capacity.

• 模型采用双重规划的思想,上层问题以小区的汽车保有量之和最大为目标函数,约束条件是路段上的汽车尾气排放不超过相应的交通环境容量;