In a city with subway system like Boston, a key to the livability of a neighborhood and the attractiveness of real estate is its walkability; specifically, the walkability of neighborhoods near transit stations. In much of Boston and the cities that make up its urban core, citizens can complete most or all of their travel by walking and using the T.
Generally, it's common wisdom in the planning world that the “average” person is willing to walk up to half a mile to reach a transit station with good frequencies. But too often, that distance is depicted on maps as a “straight-line distance” (“as the crow flies”) when a person can't actually walk through buildings, but must follow the road and pedestrian path network. The T is guilty of this if one looks on our neighborhood maps in various stations.
To more accurately illustrate the connectivity and walkability of the pedestrian network around our stations, OPMI is working on an atlas of “walksheds” around MBTA stations. We are working to finalize an accurate map of the area one can reach on foot along the pedestrian network. This work was inspired by the work of WMATA's Planning office. This post discusses the methodology, some potential uses, and discusses two examples in depth to illustrate why the distinction between straight-line buffers and walksheds is important.
Methodology
Developing the walksheds took multiple steps. To begin with, we used the roads dataset from OpenStreetMap, which has a good inventory of pedestrian paths. To model stations with multiple exits, we added pedestrian paths to the network, especially at stations like Wollaston or Orient Heights where the street network is split by the train right of way. (During this process, we actually noticed the pedestrian access to Shawmut Station was absent from the OpenStreetMap data, and we added it — hooray for open source!). We created a network dataset using ArcGIS's Network Analyst extension, and used the Service Area tool to create the walksheds themselves. We chose 400 meters (nearly 1/4 mile) and 800 meters (1/2 mile) as the distances. We then visually checked each station walkshed to see if there were any oddities. We will continue to refine these layers as we notice any inaccuracies.
Potential Applications
There are multiple potential uses for these walksheds. First of all, they provide a more accurate picture of the actual walkable area around the stations. MassDOT, the T and municipalities can use these maps to more accurately identify the properties and locations that are truly transit-accessible. Areas that are particularly far from transit can be prioritized for future improvements or route changes. Second, areas with low walkability can be identified and could be improved; for example, by adding a pedestrian path or perhaps a bridge over or around an obstacle.
Examples
Overall, the MBTA's rapid transit stations are quite walkable— as Boston is an old city, and the T is an old system, the street network probably helps in this regard. Most neighborhoods and T stations were built before private vehicles were ubiquitous. That said, there are still variations in walkability between the stations.
CENTRAL
Central is one of the more walkable stations in the MBTA system, and probably in the entire country. Cambridge has a relatively dense street grid, and the streets radiating out from Central Square also help our theoretical walker reach a large area within a half mile. The ratio of the 800 meter walkshed's area to the area of the larger circle is 0.67, which means one can reach 67% of the theoretical area along the street network that she could reach if there were no buildings or other obstacles. Note as well the overlap with the walksheds from Harvard and Kendall.
QUINCY ADAMS
By contrast, Quincy Adams is one of the least walkable heavy rail stations in the MBTA system (unsurprisingly, it has a large parking garage). The station is cut off from close-by neighborhoods by multiple obstacles: the Red Line and Commuter Rail right-of-way itself, the highway and its on-ramps, and by a closed gate on the east side of the station. The ratio of the walkshed to the theoretical walkshed is just 0.21 (and much of that walkable area is taken by surface parking lots).
Next Steps
More QA/QC will be performed on these walksheds, and then the data will be finalized. We plan to release the stations in a “walkshed atlas” with general information on the neighborhoods around the stations. The shapefiles will also be released publicly. Once the walksheds are finalized, potential projects to improve walkability can be identified and their feasibility explored.
