Madison RapidRide Network Ridership and Equity Analysis
Partner(s): Seattle Department of Transportation
Completed: March 2018
Github Repo: https://github.com/dssg/seattle_mobility
Team: Hareem Naveed, Joe Walsh, Adolfo De Unanue, and Lauren Haynes
Summary
In collaboration with the Seattle Department of Transportation (SDOT), the Center for Data Science and Public Policy at the University of Chicago (DSaPP) built the Transit Equity Visualizer, a reusable software tool for evaluating whether changes in service adversely impact minorities and other disadvantaged individuals. This work was motivated by the transit restructures that are part of the Move Seattle RapidRide Expansion Program. The City wants to improve overall transit service while ensuring that the changes do not negatively affect economically and socially underserved residents. The Transit Equity Visualizer brings together demographic and transit-use data to help transportation planners evaluate each restructure and mitigate its negative impacts.
Background
Seattle’s population and economy are booming, but not everyone benefits from the growth. As the Seattle Department of Transportation changes the transit system to meet the city’s needs, they want to ensure that they do not adversely impact protected populations. In 2019, the City of Seattle will implement high capacity transit (HCT)/Bus Rapid Transit (BRT) along Madison Street. The City wants to ensure that this and future restructures do not negatively impact economically and socially underserved residents.
Transit planners face a couple of obstacles to more informed equity analysis. First, they don’t have a tool that combines demographic and transit data, which has led them to rely on checklist-type analyses that simply ensure there is no explicit removal of service from low-income or minority areas. Second, transit planners lack a clear definition of equity, which has made it difficult to understand the effects proposed changes will have.
Scope
The goal for this project was to use data-driven methods to identify the residents (and neighborhoods) who may be at increased risk of worse transit outcomes for a given transit change and suggest transit modifications City of Seattle can make to decrease those risks, such as bus routing and stop placements.
With this in mind, DSaPP developed the Transit Equity Visualizer, a tool that overlays information about transit use with demographic information from the American Community Survey (ACS) and the Small Area Estimates Program (SAEP) to help understand the populations affected by proposed changes in transit infrastructure. It helps answer two questions critical to the planning process:
- If I remove this bus service, what populations are affected?
- If I am interested in a certain population, which routes and bus stops do they use most?
Transit planners can use the tool to evaluate each transit restructure and modify it to mitigate any negative impact.
Data
The Transit Equity Visualizer combines transit and demographic data. The transit data include
- On boardings and off boardings for each bus stop for each day
- Average number of trips between defined origins and destinations split by fare type (low income ORCA, student fare, etc), age, and time of day
- Boardings for the light rail at each stop
- Zoning Information
- Geospatial Transit Route Files
Demographic data come from the American Community Survey and the Small Area Estimates Program (SAEP) and include population percentages for minorities, Hispanics, English language difficulty, disability status, households under 200% of the poverty line, and limited access to vehicles.
Analysis
The Transit Equity Visualizer enables the user to choose the equity measure. The equity measure uses the six components mentioned above: population percentages for limited access to vehicles, minorities, English language difficulty, disability status, households under 200% of the poverty line, and ethnicity. The user can weigh each of them as appropriate. The Transit Equity Visualizer updates with the new measure.
The Transit Equity Visualizer has three tabs. The first tab maps block groups on the chosen equity measure, shows the distribution of scores, and lists the ten least equitable block groups. The second tab plots bus stop use on top of the equity map. The third tab shows the potential impact of a bus or route change. It shows the top origins and destinations and their demographics for a given bus stop.
Results
The Transit Equity Visualizer benefits Seattle in several ways. It maps populations in the city, it enables the user to choose the equity measure of interest, it reports equity at a more granular level than the City has had, and it plots transit use against equity.
The Transit Equity Visualizer has had immediate impact for Seattle’s transit planning. The City and local communities had been discussing changes to a bus route, but they had little information about who uses the stops in question. Minutes after the application went live, planners were able to see the demographics for the most popular origins and destinations and make a decision.
The Transit Equity Visualizer is relatively simple to modify and deploy. The code includes dockerfiles for simple and reliable deployment across operating systems, and the web application is written in R’s Shiny users can make changes without learning web development.
The City has deployed multiple instances of the Transit Equity Visualizer. As Seattle grapples with rapid growth and changing transit demands, they are using the tool to improve transit while mitigating potential inequities.
