Highway Externalities: Inequity Identification Tool

Date and Time: Thursday: 10:30 AM - 12:00 PM
Location: Kavli Auditorium

 

Thor Dodson, FHWA

PRESENTATION DESCRIPTION

We utilize estimates of the social cost of highway use externalities combined with spatial analysis and demographic data to calculate and visualize the inequities in exposure to highway externalities. Motorists generate a number of costs as they travel the Nation’s highways and some of these costs are “external” because they are neither borne directly by the users who create them nor are they considered in those users’ decisions to travel. While there are many external costs, this study focuses on traffic congestion, air pollution, noise pollution, and crash costs, all of which may be borne by other highway users, public agencies, or society as a whole. FHWA has developed an Externality Costs of Highway Users Analysis Tool (ECAT) to calculate the external total cost, average cost per vehicle mile traveled, marginal cost per vehicle mile traveled, broken down by State, county, vehicle type, highway functional class, and rural and urban areas across a range of low, medium, and high scenarios. We conduct a spatial analysis with ECAT to estimate where highway externalities occur and quantify the equity of externality exposure across demographic groups for highway noise and air pollution. To understand the degree of inequity, we construct externality equity ratios—the percentage of costs absorbed by a demographic group divided by their percentage of the total population within a region. An equity ratio of one implies a proportionate or fair share of the cost of noise externality by the demographic group; if the equity ratio for an externality (e.g., noise pollution) is greater than one for a demographic group, then that subpopulation is disproportionately absorbing more of the cost compared to the fair share if the externality burden was equally divided amongst society. We find significant inequities at multiple regional scales reflecting systematic differences across demographic groups in proximity to highways and therefore exposure to highway noise and air pollution. To make these results accessible to planners and policy makers, we develop an online Inequity Identification Tool (IIT) that integrates multiple spatial layers to visualize the equity results of ECAT at a macro as well as micro geographic scale. By visualizing the results as map layers, regions with inequities are easily identified as well as which roads are contributing to the inequity and where overburdened populations are located. The tool also features interactive results and data analysis through Tableau. Additionally, the tool can integrate other spatial layers such as redlining maps from the 1930s Home Owners Loan Corporation to understand how historical policy contributed to ongoing inequities. IIT supports efforts for mitigation measures intended to target underserved and overburdened communities, as well as provides context for highway projects considering equity to understand if a project is contributing to an existing inequity or reducing it. The visualization by IIT enables planners and policy makers to easily view the ECAT equity results and connect them to specific highways segments, understanding the costs of highway noise in addition to who is affected.

SPEAKER BIOGRAPHY

Thor Dodson is an economist with the Federal Highway Administration in the Office of Policy. He works on the Externality Cost Assessment Tool (ECAT), the National Highway Construction Cost Index (NHCCI), conducts benefit cost analysis review of highway projects for discretionary grant programs, and provides support for a variety of projects in the Office of Transportation Policy Studies.

PRESENTATION FILE