Science Inventory

A System Dynamics Model for Integrated Decision Making: The Durham-Orange Light Rail Project


Kolling, J., L. Cox, N. Flanders, A. Procter, N. Tanners, A. Bassi, AND R. Araujo. A System Dynamics Model for Integrated Decision Making: The Durham-Orange Light Rail Project. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/333, 2016.


The United States Environmental Protection Agency (US EPA) Sustainable and Healthy Communities Research Program (SHC) has committed to developing systems approaches that enable communities to act on an enhanced understanding of these interconnections and to comprehensively account for the full costs and benefits of community decisions in the social, economic, and environmental dimensions. This report documents the development and testing of a system dynamics (SD) model as a decision support tool for community sustainability with the proposed Durham-Orange Light Rail Project (D-O LRP) in Durham and Orange Counties, North Carolina, as a case-study.


EPA’s Sustainable and Healthy Communities Research Program (SHC) is conducting transdisciplinary research to inform and empower decision-makers. EPA tools and approaches are being developed to enable communities to effectively weigh and integrate human health, socioeconomic, environmental, and ecological factors into their decisions to promote community sustainability. To help achieve this goal, EPA researchers have developed systems approaches to account for the linkages among resources, assets, and outcomes managed by a community. System dynamics (SD) is a member of the family of systems approaches and provides a framework for dynamic modeling that can assist with assessing and understanding complex issues across multiple dimensions. To test the utility of such tools when applied to a real-world situation, the EPA has developed a prototype SD model for community sustainability using the proposed Durham-Orange Light Rail Project (D-O LRP) as a case study.The EPA D-O LRP SD modeling team chose the proposed D-O LRP to demonstrate that an integrated modeling approach could represent the multitude of related cross-sectoral decisions that would be made and the cascading impacts that could result from a light rail transit system connecting Durham and Chapel Hill, NC. In keeping with the SHC vision described above, the proposal for the light rail is a starting point solution for the more intractable problems of population growth, unsustainable land use, environmental degradation, and the persistence of economic, social, and health inequities. To achieve the maximum potential benefits from the light rail across all of the dimensions of sustainability while reducing its potential negative consequences, concurrent policies must be weighed in combination with the light rail to assess the tradeoffs associated with these decisions. Therefore, the D-O LRP SD modeling team developed many concurrent policy scenarios in addition to the light rail that can aid stakeholders in finding leverage points within the system where interventions can have the largest impact.In the first phase of this modeling effort, a conceptual model for the D-O LRP was designed with a high degree of input from stakeholders, including representatives from the regional transit authority, county health department, stormwater management department, and city and regional land use and transportation planning departments, among others. This conceptual model served as a framework for the operational SD model, which was built to evaluate a number of policy scenarios, many of which were also suggested by stakeholders. The operational model was subjected to rigorous quality assurance tests, including the sensitivity of the model to assumptions and inputs, and the evaluation of outcomes – social, economic, and environmental – resulting from actions that emanate from or impinge on the D-O LRP. To request a copy of the D-O LRP SD Model, viewable using Vensim® Model Reader (, email:


D-O LRP SD Model Full Documentation Report  (PDF, NA pp,  7914  KB,  about PDF)

Executive Summary  (PDF, NA pp,  703  KB,  about PDF)

Durham Pilot Fact Sheet  (PDF, NA pp,  569  KB,  about PDF)

Record Details:

Product Published Date:01/25/2016
Record Last Revised:05/20/2016
OMB Category:Other
Record ID: 310977