Neighborhood Mobility Balance: 2010 White Flint Town Hall

Neighborhood Mobility Balance: 2010 White Flint Town Hall

Ian Lockwood, an expert in traffic calming and mobility design, with the firm of AEcom, formerly known as Glatting Jackson, is the presenter at the 2010 White Flint Town Hall. Live-blogging from his presentation.

Quick summary: old traffic calming methods focussed on physical barriers, which had many problems. Newer methods look at influencing drivers’ behavior through psychology. Throughout the world, traffic calming, done right, can reduce carbon emissions and congestion, increase property values, and create a sense of “place” in a community.

Lockwood did his graduate work on traffic calming at a time before it was well-known. In fact, there wasn’t any good academic work at the time, so he was a pioneer in the field.

The traffic calming experience in North America is about twenty years old, but in other countries it is much older. Traffic calming is now a widespread field.

With the increase in the number of people driving, the problems are exacerbated much more so than in the 1980’s. Traffic calming is physically changing the nature of the street to result in calmer traffic. Ian took a tour of neighborhoods today; he took a similar tour only a few years ago, but things have changed in only that short time. Driver expectations have changed and aggressive behavior has changed.

Traffic calming will result in fewer deaths on the street. All has to do with reducing speeds, so more likely to reduce collisions. Fields of vision expand so drivers can see more. At higher speeds, drivers focus further away; at slower speeds, drivers focus closer. Collisions at 40 mph result in 80% of pedestrian victims dying; at 20mph only 5% die.

Traffic control devices are attempts to communicate with you, like a stop sign. Route modifications like street closures remove in a less connected neighborhood; generally we don’t support them any more, because they always created winners and losers. Someone always wanted them on someone else’s street. It pits neighbor against neighbor. All these behaviors are avoidable if you change driver behavior. Street scaping is principally a beautification measure.

Traffic calming is directly addressing driver behavior by slowing them down. Slower routes reduce cut-through traffic.

Planners split streets into 2 categories: framework streets that collect and distribute traffic. Most arterial streets are framework streets, but also some neighborhood streets, such as Tilden Lane. On non-framework streets, there are more options for calming, including changing the cross-section of the street.  Bulb-outs shorten the width of the streets, reducing the crossing distance for pedestrians, helping to enforce parking rules, and controlling drivers’ expectations. Putting trees in them creates a beautiful sense of closure.

Speed bumps – 2-3 inches high — aren’t allowed on public streets because they don’t work but hurt  cars. Speed humps, on the other hand, are some of the most effective measures. If you add sufficient numbers of measures, deployed properly, the crash rate drops by half.

Ian presented a long series of examples of calming devices from around the country and the world. Many of these were around schools.

One of the things to use in White Flint neighborhoods would be “marking your territory.” Identify to drivers that they are entering a neighborhood, and moving out of high-speed streets. Make the landscaping conspicuous or use signs. The key is coming up with a menu of measures, space them correctly, don’t use too many, and stage your implementation.

Traffic calm enough, stop, see if it solves your issues. Then do more if needed, but if your problem is solved, then stop.

In White Flint neighborhoods, there are lot of double yellow lines on neighborhood streets. That is the wrong vocabulary for a local street. Double yellow lines are highway markings, and they communicate higher speeds to drivers. Plus, at night, drivers focus on the lines, and more pedestrians are at risk.

Your streets are the biggest public realm in your neighborhood, more than parks. People identify with them, and identify your neighborhood by the streets. They should be carefully designed for multiple purposes to help define and develop the neighborhood, not just move cars. For example, use “rain gardens” designed to accept water in a natural setting, rather than iron storm grates.

Several places in White Flint neighborhoods are good candidates for roundabouts. They reduce speeding and are good candidates to replace signals, without the overhead machinery. Roundabouts are safer than signals, but not the larger traffic circles. You can walk easily across them, and they reduce crashes. Hugely safer for pedestrians. At a signal, traffic is coming at pedestrians from all angles, but in a roundabout, traffic approaches only from one direction. Circles have higher traffic speeds because they are so big. Maintaining a roundabout is much cheaper than a signalized intersection. Huge reduction on how much fuel is used as well, so some federal funds are available for roundabouts from energy reduction programs.

On Route 50 near Centreville in Virginia, Ian put in four roundabouts. The congestion is gone and accident rates are way down. In California, he narrowed a five lane signalized road to a two lane road with a roundabout and not only cleared congestion, but enlivened the community. A new restaurant opened named the Roundabout.

Tuckerman at Old Georgetown, or Tilden at Old Georgetown could be candidates for testing for roundabouts.

In the old days, streets were “shared space,” without sidewalks or double yellow lines. 1904 video of streetcar in San Francisco (Youtube it) shows “the flow of the city” across the street. In shared spaces in England, Finland and Switzerland, accident rates go down. A big difference is the paving, and the attitude of the municipality.

Cause drivers to take responsibility for their own behavior. The environment tells them what to do. Get drivers to focus on the near and middle distance. All about place and emphasizing people and not motorists.

Traffic calming plans tend to be very simple and clear, so they can be implemented in stages. They use only a couple of methods uniformly across an area, rather than all possible devices.

Emphasize place, not throughput or speed. Design in context. Inappropriate places “violate your space” and neighborhood. Emphasizing speed and reducing travel time actually increases sprawl, not to mention energy use. As soon as your reward the unsustainable trip, the land use changes to respond, exacerbating your problems. Instead reward the sustainable trip, the short trip, the biking trip. The person cutting through the city is not as important as the city itself; they can still go through, but on the city’s terms, not the highway’s. 

Change of attitude toward highways; as they come down, new land is made available. Think about all the quality of life issues in the area. It’s not just traffic calming; it’s context-sensitive design. Complete streets. Smart transportation. Safe routes to schools. Just competent street design. Vibrant uses made possible by good street design.

You still have to accomodate the motorist, but let’s level the playing field for the pedestrian, the bicyclist, the kids. You get a better community over time. You can replace many traffic lanes with good design, with many benefits for the surrounding neighborhood.

Summarizing some of the calming methods most likely to prove useful in White Flint neighborhoods, Ian saw many similarities through several neighborhoods, including limited access. Those tend to have “cut-through traffic” issues, although studies show that most such traffic is from neighborhood residents and visitors. Deal with the busiest streets first. Deal with your entrances so drivers know they’re entering a special place. Remove double yellow lines. “I would highly discourage closing off your streets, because you’ll just re-route the traffic to your neighbors’ streets.”

Ian Lockwood will be holding meetings tomorrow with individual neighborhoods. For more information, see

Barnaby Zall

Barnaby Zall


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