为了有效改善路网运行状态，借鉴网络可靠性分析方法。对路网进行了畅通可靠性分析；针对路网可选规划方案过多的问题，通过单元重要性分析，确定数量合理的公路网新建或改建备选方案集合，并以路网综合效益最大为目标，建立公路网络规划方案优化的模型；利用枚举法等离散优化方法。确定最优公路网规划方案。通过实例计算证明，利用本文提出的模型及方法可以得到合理的路网布局优化方案。

在单元可靠性分析的基础上，以路网综合效益最大作为优化目标，并考虑道路建设的投资约束，建立公路网建设投资优化模型。利用该方法确定的规划公路网建设项目，不仅实现了建设资金的有效利用，而且满足了路网系统和道路单元的交通需求的不断增长。实例表明，该方法具有较强的实用性及可行性。

将城市震后交通系统运行划分为两个阶段：震后应急阶段及震后恢复阶段，并根据地震环境下不同恢复阶段的社会经济活动及交通系统特性对传统交通预测四阶段法——出行产生、出行分布、方式划分、交通分配的宏观模型进行修正，讨论不同模型参数的变化趋势，建议参数的调整原则及方法，进而以修正四阶段法为基础进行震后交通需求预测。该方法简便易行，预测结果可对城市交通系统防灾规划提供决策依据。

Depending on the randomness of traffic demand and supply analysis, the paper presents the concept of unblocked reliability and the evaluation methods for road component and network system. Taking the unblocked reliability of the road system as optimization objective, the improvement optimization model of urban transportation network is built. Through the component importance analysis and genetic algorithm, the solution can be found effectively. In the end of the paper, an example is given to illuminate the practicability and maneuverability of the suggested probability assessment index and optimum methodology for the urban transportation network.

In this paper, a revised four-stage traffic plan method is proposed to estimate the post-earthquake traffic flow assigned to a road network. We also suggest a post-earthquake road capacity estimation method that considers the seismic vulnerability of structures and the potential building collapse area that might occupy a road after a major earthquake. Through an analysis of the "randomicity" of traffic demands (traffic flow) and road capacities after an earthquake, and depending on reliability theory, the "unblocked" reliability of road segments and the reliability of the entire transportation network can be estimated using techniques presented in this paper. Through the component importance analysis, the optimum improvement and thus, optimum recovery plan for a transportation system that focuses on alleviating earthquake indirect losses is suggested. At the end of this paper, an example is given to illustrate the application of the unblocked reliability index in post-earthquake traffic condition estimation and in developing earthquake response strategies for urban transportation systems.