Beyond mobility—prioritizing accessibility in urban transportation

By Mary Ebeling

The San Francisco Transit Accessibility Map is a new online tool showing how much of the city is accessible by transit or walking within a selected travel time. Designed for the San Francisco Metropolitan Transit Authority primarily for agency use, the mapping tool is getting a lot of attention from transit advocates and bloggers. San Francisco residents can now easily see how both their residential location and transit reliability will affect their commute times.

The maps currently show what areas of the city and how many jobs can be accessed from a specific location using transit travel times under best case, average, and worst case scenarios. A second option allows a user to see what percentage of the city is accessible within the selected travel time from any origin location. Users can change the time of day for travel and select their maximum travel time to view how that changes access.

Although the map is useful as is, it also presents an enormous opportunity to develop a richly layered analysis that could be used to understand accessibility more broadly by adding data on non-work as well as work destinations. It could also highlight the need to improve accessibility for underserved areas.

Using past performance data, planners can see areas of the city that need transit improvements, and make effective arguments for where to focus future transit investments based on this data. The public can see how transit access and times would change if proposed improvements are implemented. Importantly, the tool calculates travel times based on the full trip—the time to walk or bike to a stop, wait time, time on the bus/train, and walk to final destination.

By adding additional data layers, tools such as this represent an opportunity to improve transit service specifically, and multimodal transportation more generally, for underserved populations and neighborhoods. Communities embarking on transportation equity initiatives might add a GIS layer with census data, making it possible to look at transit accessibility by income, age, ethnicity, or other variables. In addition to job accessibility, which the map shows, the addition of data on access to non-work destinations—education, libraries, retail, healthcare, etc.—could tell planners how well transit serves a wide range of population groups and destinations in the city.

The SF Transit Accessibility Map is one of a growing number of practice-ready tools for measuring accessibility. Some of these tools focus on specific modes, where others focus on specific issues, such as equity. As data becomes both easier to acquire and represent to policy makers and the public, discussions of transportation investments and priorities can be enriched by using these tools. SFMTA will be adding additional measurement options and data layers as they update the maps with 2015 data.

Mary Ebeling is a Transportation Policy Analyst at SSTI.