考虑风险、不确定性及相关性的交通项目全寿命周期评估与优化投资决策

Transportation is essential to the nation’s economic development. In each year, a significant amount of investments is made to build, reconstruct, repair, and operate various types of physical transportation facilities in support of overall system performance. Project evaluation and selection are two critical analytical steps in transportation investment decision-making. For project evaluation, benefits of a project implemented on a link or node of a transportation network is computed as net reductions in agency and user costs in the facility service life-cycle. Agency cost items primarily include costs of constructing, preserving, and maintaining physical facilities, while user cost items are associated with vehicle operations, travel time, crashes, and air emissions. The project benefits are regarded as agency and user cost reductions. Through project evaluation, all economically feasible candidate projects could be identified. Due to budget constraints, not all such projects are selected for actual implementation. Thus, project selection aims to identify the best sub-collection of economically feasible projects to yield maximized overall benefits under budget and other constraints. .Some limitations are found in current methods, models, and solution algorithms for project evaluation and selection, particularly in reliable traffic forecasts in the facility service life-cycle, risk and uncertainty of input factors involved with agency and user cost estimation, and interdependencies in benefits of multi-project implementation. This will likely produce biased decision outcomes..The proposed study first employs regional travel demand model, coupled with properly calibrated, validated, and timely updated origin-destination (OD) trip matrix to keep abreast of demand or supply changes to produce reliable traffic forecasts corresponding to OD adjustment years. It then uses extrapolation with annual growth factors to establish traffic forecasts for interim years. .For single project evaluation, risk and uncertainty analysis is conducted for such input factors as facility service life, construction and repair costs, traffic forecasts, and discount rate for calculating life-cycle agency and user costs before and after project implementation, and project benefits..Further, interdependencies in benefits of jointly implementing multiple projects potentially caused by differences in redistributed traffic between jointly implementing multiple projects and separately implementing the same set of projects one at a time. As such, interdependencies in benefits of joint project implementation are assessed by traffic redistribution outcomes. Once confirming interdependency effects, a reduction rule is introduced to remove some possible joint project implementation scenarios to create a subset of virtually all economically efficient, small-numbered joint project implementation scenarios to ensure practicality of analysis in presence of many candidate projects, as enumeration of all possible scenarios grows exponentially. Next, a method is introduced to estimate the extent of interdependencies in multi-project benefits. Two subsets of economically feasible projects are created: one contains separately implemented projects without interdependencies and the other includes jointly implemented projects with interdependencies. .Finally, the two subsets of economically feasible projects are used as inputs of models and solution algorithms for project selection that yields maximized overall benefits under budget and other constraints without and with project interdependency considerations, respectively. The research products include new methods, models, and solution algorithms, as well as their real-world applications, providing a new venue and theoretical foundation for optimal decision-making of transportation investments.

交通作为国民经济发展的命脉，每年都有巨额的设施新建、改建和运维投入，以维持服务绩效。项目评估和优选是交通投资决策的两个关键步骤。评估可核实备选项目的经济可行性，而优选则可从经济可行的项目中找出最佳实施组合。现有交通项目评估和优选的方法、模型及算法在交通流的预测、计算参数的风险和不确定性分析，以及多个项目相关性考量等方面存在局限性。本研究引入区域交通分配模型、依托校准和调整的OD出行矩阵、结合外推法，实现交通设施全寿命周期历年交通流的预测；针对单一项目评估，将设施寿命、建设和运维成本、交通流、折现率等计算参数的风险和不确定性界定及分析纳入全寿命周期机构和用户成本及收益估算；拓展至有相关性的多个项目组合实施评估，着重建立项目相关性评判、筛选实际应用中可操作的高收益项目组合实施子集，以及项目收益的相关度估算方法；并提出项目优选的模型及求解算法。研究成果为交通投资决策提供了新的视角和理论基础。

在交通项目投资决策中，项目评估和项目选择是两个关键的步骤。项目评估的目的是对所有备选项目进行成本和收益核算，以确定其经济可行性；项目选择的目的是在预算等约束条件下，从所有经济可行的备选项目中选择能最大化投资收益的项目子集。本研究围绕项目评估和项目选择中涉及的计算参数风险及不确定问题、多个备选项目之间可能存在的相关性问题以及预算约束下交通项目多绩效指标权衡分析方法开展针对性研究。主要成果表现在以下方面：（1）研究了全寿命周期成本分析中，计算参数风险和不确定性的数学表达，使用贝塔分布和Latin hypercube抽样技术对具备风险性的因素进行参数标定，使用Shackle 模型和相关决策规则标定具备不确定性的参数，并建立了在确定性、风险、不确定性情况下交通项目全寿命周期成本/收益分析框架。（2）研究了多个交通项目同时实施时，可能存在的项目相关性问题，对相关性建立了数学表达和量化分析，在传统背包模型基础上，建立超图背包模型，用于有相关性的多个交通项目全寿命周期评估及选择，并开发相应求解算法。（3）研究了考虑预算约束的交通项目权衡分析方法，提出了一种基于绩效的多指标交通预算分配方法，整合了赫芬达尔-赫希曼指数（Herfindahl-Hirschman Index , HHI）、折中规划（compromise programming, CP）和ε-约束方法，建立数学模型并开发求解算法。目前本项目已正式发表期刊论文10篇（SCI/SSCI检索论文9篇，中文核心论文1篇），在投SCI/SSCI论文3篇，在审国家发明专利2项，支持完成硕士及博士研究生学位论文12篇，已经较好地完成了原定的科研产出目标。