Solving the Region’s Congestion Woes – One Step at a Time

March 17th, 2014

One solution to the region’s crippling congestion could be right under our feet – literally.

This post is part one of a three-part series.

Illustration of possible walkability improvements that could occur in/around Tysons Corner. From Regional Transit System Plan


The region is abuzz with $220B of planned new transportation investments – the Purple Line, HOT Lanes, new streetcar lines, and additional roadways. Though there is not one dollar currently pledged to add capacity to Metro, these other investments may help the region chart a course away from leading the country in congestion (pdf).

However, for a quarter trillion dollars, one would expect that collectively these projects would have significant impacts on the region’s congestion. While there are some benefits – vehicle miles traveled (VMT) per capita are expected to decline and  transit mode share may increase by one percent – overall increases in VMT are expected to outpace road construction, leading to a 38% increase in the number of lane miles of congestion (pdf). But is there another way to get more bang for our buck?

Make station areas walkable. Every one of them. Now.

The above maps of Tysons Corner are an example of an area that is seeking to transform to maximize the recent transit investments in the Silver Line. We know the car-centric nature of today’s Tysons – wide roads, highway ramps, few sidewalks and crosswalks, superblocks with few intersections, and big parking lots that separate the building from the street. All of this comes together and creates an environment that does not invite walking or biking. Fairfax County has outlined their plans in Transforming Tysons by 2050, but that’s more than a few years away. What are the components that would make station areas (more) walkable in the nearer term? What do you notice in the different illustrations above?

We can get super wonky, like this Transportation Research Board paper on Measuring Network Connectivity but we’ll spare you the formulas and three-letter acronyms. Essentially, station areas need the following physical elements to be walkable:

  • High block density: indicating that there are more blocks in a given area that allow multiple paths to reach a destination;
  • Intersection density: indicating that there are more intersections in a given area that allow multiple crossing points;
  • Block size: Maximum area or perimeter of a block;
  • Directness of walking routes: indicating that pedestrians are not forced into circuitous routes compared to straight line distance;
  • Existence of a street grid with different street types;
  • Sidewalks everywhere; and
  • Crosswalks on every side at every intersection and where needed, at mid-blocks;

And the list above doesn’t even speak to the aesthetics and adjacent uses of walkable areas, which could envelope another blog post! Here’s an example from two existing Metrorail station areas – Takoma and Landover  – with a half-mile walk shed based on the pedestrian network shown in blue. As you can see, they vary widely in terms of the physical elements of the surrounding area. Not surprisingly, ridership and access mode share are also quite different.  All-day ridership, on average, at Takoma is north of 6,000 passengers per day, while all-day boardings at Landover, despite having massive amounts of parking nearby, is just over 2,000.

Why might be the case?  Takoma enables access from both sides of the rail corridor, has many more intersections, a grid of streets, plenty of sidewalks and crosswalks, and for many people, their walk route is fairly direct. Landover – while also providing sidewalks — only provides one, winding access point, a few large blocks, and few crossings of major roads. (See more examples.)

Half-mile walk from two different Metrorail stations. Given the pedestrian environment, you can walk to four times more land area at Takoma than Landover.

These maps show a half-mile walk from two different Metrorail stations, as examples. Guess which station has higher ridership?

Could we not take tens of thousands of cars off the road in the next few years simply by constructing fine-grained pedestrian access networks in station areas that currently lack these? And combine that strategy with a relentless focus on promoting dense, car-lite development at these station areas? If that promise were real, wouldn’t it represent a low-cost, high-impact way to use our existing infrastructure to deliver a crushing blow to congestion, improve mobility, sustain economic growth, and potentially reduce Metro’s annual operating subsidy?

Check back tomorrow to read part two of our series to find out and better understand the power of simple solutions – in this case, of making every Metro station areas walkable.


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  1. Alan
    March 18th, 2014 at 14:52 | #1

    One thing about walkability that I like is that it can be done on a relatively smaller scale that vehicle circulation. You can implement a walkable/bikeable grid without putting in lots of new miles of roadway if its not needed. A big parcel can be sub divided by a few 10′ wide multiuse paths and maybe only one driveway and underground parking if its adjacent to a metro station and a lot of traffic is on foot. The Courthouse area in Arlington is a good example

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