The Geometry of Transit-Friendly Neighborhoods
"Transit-oriented development" sounds like a tidy solution to myriad urban ills. If cities enabled more people to live and work within strolling distance of a train or bus stop, families could save money on gas, residents without cars could more easily get to work, neighborhoods could cut down on congestion and pollution, and economic development might ensue. As a general theory, it simply makes sense for cities to invest in the nodes that connect us to each other and the places where we need to go.
That said, every rail stop isn’t equally primed for a new apartment complex and a Whole Foods. And it can be hard to finger why. There’s little sense, for instance, in pushing transit-oriented development in a community where every household already owns two cars. Nor does it make sense in the center of a neighborhood sliced by highways and mega blocks where residents are unlikely to walk to the train.
The question of where to invest in transit-oriented development is a complicated one. We recently stumbled across a smart way of visualizing the answer – with “typology radar graphs!” – from the Center for Transit-Oriented Development.
Last week, the center released an extensive study of more than 100 transit stops in the Pittsburgh area. Glancing across all of them, how are transit agencies supposed to know where to invest limited funds to boost the prospects for a transit-oriented community? And how should developers figure out where new projects might succeed?
Take, for instance, the Chatham Square station on the planned Oakland-to-downtown bus rapid transit line.
That pentagon measures what CTOD director Abigail Thorne-Lyman calls the "transit orientation" of the neighborhood today. In these five quantifiable metrics, the point for "people" represents the population density of the neighborhood (Chatham Square is among the best performers in the region on this metric). Its "physical form" refers to assets like small blocks that make the area naturally walkable. "De(P)endence" refers to how extensively local residents own and rely on private cars. "Places" covers whether or not there are nearby amenities like restaurants, grocery stores and retail. And "proximity" refers to the station’s travel-time distance to employment hubs.
Chatham Square was among the best overall, though car dependence is a little high. (In an ideal neighborhood, the entire pentagon would be filled in.) It’s the kind of place that currently supports transit-oriented lifestyles. There’s probably not much more that local transit agencies need to do to invest in this area. And developers would do well to pursue opportunities here, although there’s not much land left for new development, and land values correspondingly run high (CTOD has produced a second set of diagrams capturing this picture of potential future development for each station, which you can view in PDF form here).
By contrast, this is the Casswell stop on the light-rail Red Line:
That sad little blob in the middle of the pentagon succinctly tells us that this area is sparsely populated (with the kind of land-use patterns that accompany exurban development). It has high car dependence and few amenities, and it’s far from downtown Pittsburgh. This is a place where TOD probably won’t succeed, either through the efforts of transit planners or property developers.
The vast majority of the transit stops in the region sit somewhere between these two, with varying assets and areas for improvement. "A quarter to a half of the station areas in the system could benefit from a small infrastructure investment today, be that a pedestrian bridge or signage that just shows where the station is, pedestrian tunnels, paths that are paved, sidewalks,” Thorne-Lyman says. "Small things can make a big difference."
The geometry of these graphs can help illustrate where those changes are needed.
On the Oakland to Downtown BRT
On the Blue Line light rail
On the Oakland to Downtown BRT
Those pictures also plainly illustrate the complex ways that density, land use, car dependency and distance all shape communities differently.
"It’s a very simplistic way of measuring what you need," Thorne-Lyman says. “But if you don’t have the resources to even know where to begin, it’s very powerful to say ‘I’m just going to look at these five things, and what do I need to improve to push myself into a more transit-oriented urban form?'"