基于四阶矩的路网总行程时间可靠性评价

为了评价供需服从任意分布时的路网总行程时间可靠性，提出一种基于四阶矩的计算方法.通过计算机模拟计算出路网出行总时间的四阶矩，然后推导总行程时间预算与四阶矩之间的关系，继而定义了路网总行程时间可靠性，并采用逆向求解方程得到该值.通过在大型算例路网上进行测试，得到该网络的不同预算下的总行程时间可靠性.分析结果表明，路网总行程时间可靠性随着总行程时间预算的增加而增加，当增加到一定程度时，可靠性趋于稳定值1.0，完全符合实际情况，从而说明计算机模拟加上逆向求解的基于四阶矩的可靠性算法是一个有效的算法，可以很好地应用在供需随机分布路网的行程时间可靠性研究中.

Evaluation of Road Network Total Travel Time Reliability Based on Fourth-moment

In order to evaluate the road network total travel time reliability (TTTR) under arbitrarily distributed supply and demand, a method based on fourth-moment is proposed. The fourth-moment of road network total travel time is computed through computer simulation. Then the relationship between the total travel time budget (TTTB) and the fourth-moment is derived. The TTTR of road network is defined, and a reverse method is applied to solve an equation to get it. Test is carried out on a large-scale road network. The TTTRs of the road network are obtained under different TTTBs. The analysis results indicate that the TTTR of road network increases with the rise of the TTTB. When the TTTR reach to some extent, it becomes a fixed value 1.0, which accords with the actual situation completely. Therefore，the reliability algorithm based on the fourth-moment by using the computer simulation and the reverse method is an effective algorithm. It can be well applied to the travel time reliability of road network with stochastic supply and stochastic demand.