A different kind of density in Atlanta: street intersections

The design of a neighborhood’s street network has a major impact on the ability of pedestrians and cyclists to travel efficiently to nearby destinations, and the ability of transit routes to serve neighborhoods well. Take a look at the two maps below for examples of the extremes of street connectivity in Atlanta.

Unwalkable Buckhead

This is the street pattern in West Buckhead, a district of posh, detached homes in northwest Atlanta. Imagine trying to walk from a place at the top of this map to a place at the bottom. You wouldn’t be able to do it with the street network pictured.

Now let’s look at the polar opposite of this street pattern, a few miles away…

Walkable English Avenue

At the exact same scale as the above map, here’s one of the English Avenue neighborhood, west of Downtown.

Again, try to imagine walking from a place at the top of this map to the bottom. There are several avenues for doing so. This is not purely because of the “grid” pattern in itself, but mainly because of the high density of intersections in this area. There are dozens of intersections of streets here, providing plenty of routes for walking.

Intersection density benefits transit, health

Numerous studies have shown that people living in neighborhoods with higher “street intersection density” tend to drive less and walk and take transit more.

In one study, the likelihood of transit use was strongly associated with easy access to a transit stop. Meaning: high intersection density and street connectivity is great for providing multiple routes to transit stops, which serves the needs of transit riders — and it also serves the needs of transit providers by increasing route choices for buses.

Additionally, higher street intersection density is associated with less per capita air pollution (e.g., nitrogen oxides, carbon dioxide, and ozone) from vehicle emissions, which benefits human health and the mitigation of climate change.

(Info source: “Pedestrian-Oriented Street Intersection Density,” enviroatlas.epa.gov)

What this means for Atlanta

When we plan our city’s growth, there’s a clear benefit to matching a high density of development with street intersections for a sustainable level of walkability and transit service.

But some growth is going into formerly industrial spaces that have a problematic level of disconnected streets. Take a look at this picture from the area near the intersection of Howell Mill Road and West Marietta Street in northwest Atlanta, which used to house industrial properties.

There’s a freight rail line that separates a large group of apartments (on the right) from a hotbed of growth on Howell Mill Road, where you’ll find many destinations such as shops and restaurants. Unfortunately, one street crosses the tracks, just out of view to the bottom of the image.

The situation is not hopeless for walkability here. But this set of tracks, in addition to a large water treatment plant on the north end, do provide stumbling blocks. This may be connected to the large number of parking facilities all around, implying that there’s more car use here than would otherwise be seen if the street network was more conducive to walking.

On the other hand, look at this photo of the streets around the Garnett MARTA Station in Downtown Atlanta, and notice the classic street grid and connectivity going underused as parking.

Here’s a spot with a nice density of street intersections, with potential for walkable growth that’s going untapped.

Atlanta tends to favor a corridor-based type of growth, where long strips of main roads get filled with new development. This is what can be seen above on Howell Mill Road, as well as on other corridors such as Memorial Drive in east Atlanta and Peachtree Road in Buckhead.

In this places, you’ll find apartments and offices springing up on a linear path down a single road, often with freight rail or interstate highways alongside. It’s worth questioning whether or not we’re setting a stage for walkability with this corridor focus.

Are we taking advantage of the benefits of street intersection density to the level we should be, for sustainable outcomes? I don’t have an answer, but I sense this question isn’t being asked enough given the impact this issue has.