Integrative Freight Market Simulation

综合货运市场模拟(IFMS)试图描绘一幅全面的货运流动图景，其中既考虑了用户侧(即商品流动)，也考虑了物流侧(即车辆出行)。这一框架有可能克服基于商品的模型和车辆出行模型的局限性。基于商品的模型在考虑空车流动(这是物流决策的结果)方面有很大的局限性，而车辆出行模型无法考虑货物的经济特征。IFMS基于市场均衡公式来刻画货运供应商之间的竞争，以及路径问题的子集来表示这些公司在提货和送货时的行为。IFMS需要一种双层方法，在这种方法中，顶层对应于对符合古诺-纳什均衡的服务提供的估计，而底层侧重于在大规模模拟-优化问题的背景下，构建满足古诺-纳什解和剩余系统约束的旅游。系统的制约因素分为：a)初级；b)次级。主要的约束是：i)货运公司在市场均衡的背景下最大化利润；ii)满足用户需求，即运输每个区域生产和吸引的商品。次要约束是：iii)所得到的出行链与已知的出行链数据一致；以及iv)所得到的商用车交通与次要数据源(例如，其交通数据)一致。该项目将侧重于解决综合财务管理系统的最基本情况，同时考虑到主要的制约因素(I和II)，即主要综合财务管理系统。这将需要开发解决方案算法，以获得与提供服务的古诺-纳什解决方案(根据假定的经济参数)和用户要求相一致的路由模式。这将需要定义一组合成的、但有意义的测试用例，这些测试用例旨在表示不同规模和复杂程度的城市区域。这些案例将由若干数据集组成：1.分区系统；2.一组相关的经济参数；3.一组商用车运营商；4.一组用户要求；以及5.一组商用车行程。换句话说，将创建一组所有相关信息都已知的综合案例。将要求货运业代表进行合作，以确保对测试案例作出有意义和现实的定义。它们的输入对于数据集3、4和5的创建特别重要。将开发算法来求解主要的IFMS，并将其应用于这些测试案例。输入数据将由数据集1、2、3和4组成。算法的合理性和效率将通过确定它们能够很好地估计商用车行程(数据集5)来评估。该奖项是根据工程运输业(ETI)项目的探索性研究而颁发的。

The Integrative Freight Market Simulation (IFMS) attempts to depict a comprehensive picture of freight movements, in which both the user side, i.e., commodity flows, and the logistic side, i.e., vehicle-trips, are considered. This framework has the potential to overcome the limitations of both commodity based models and vehicle-trip models. Commodity based models have great limitations in considering the flow of empty vehicles (which are the result of logistic decisions), while vehicle trip models are unable to take into account the economic characteristics of the cargoes.The IFMS is based on a market equilibrium formulation that depict the competition among freight transportation providers, and a subset of routing problems to represent the actions of these companies when picking up and delivering the goods. The IFMS entails a bi-level approach in which the top level corresponds to the estimation of the provision of service consistent with Cournot-Nash equilibrium, while the bottom level focuses on the construction of tours that satisfy the Cournot-Nash solution and the remaining system constraints, in a context of a large scale simulation-optimization problem. The system constraints have been classified in: a) Primary; and b) Secondary. The primary constraints are: I) freight transportation companies maximize profits in a context of market equilibrium; and II) the user requirements are met, i.e., the commodities produced by and attracted to each zone are transported. Secondary constraints are: III) the resulting trip chains are consistent with known trip chain data; and IV) the resulting commercial vehicle traffic is consistent with secondary data sources, e.g., ITS traffic data. This project will focus on solving the most basic case of IFMS, taking into account the primary constraints (I and II), referred to as the Primary IFMS. This would entail developing solution algorithms that obtain the routing patterns that are consistent with both the Cournot-Nash solution for the provision of service (based on assumed economic parameters) and the user requirements. This will entail the definition of a set of synthetic, though meaningful, test cases that are meant to represent urban areas of different sizes and levels of complexity. These cases will be comprised of a number of data sets: 1. zoning system; 2. set of relevant economic parameters;3. a set of commercial vehicle operators;4. a set of user requirements; and,5. a set of commercial vehicle trips.In other words, a set of synthetic cases for which all relevant information is known will be created. The collaboration of freight industry representatives will be requested to ensure a meaningful and realistic definition of the test cases. Their input is particularly important for the creation of data sets 3, 4, and 5. Algorithms will be developed to solve the Primary IFMS and applied to these test cases. The input data will be comprised of the data sets 1, 2, 3, and 4. The reasonableness and efficiency of the algorithms will be assessed by determining how well they are able to estimate the commercial vehicle trips (data set 5).This award is made under the Exploratory Research on Engineering the Transport Industries (ETI) program solicitation.