Bikes Count

Arlington County's efforts at collecting hard data on bicycle use helps guide and evaluate the effectiveness of its planning for bikes.

Even the most casual of observers could tell you that cycling has been on the rise the past few years in Arlington. But as encouraging as that observation may be, it's not a particularly helpful one, especially if you’re trying to make sure that the streets are safe for increasing numbers of cyclists.

Arlington County recognized this problem a few years ago and has built a network of automated counters that recognize bikes and pedestrians at key points on our streets and trails.

Traffic engineers have been using automated data collection for years, but almost exclusively for vehicles. Those looking for better data about cycling traffic have usually relied on staff or volunteers actually standing along a trail or road and counting bikes as they go by. Arlington County started out using volunteer counters years ago.

Unfortunately, human counts aren’t a terribly reliable approach, and since they only take place a few hours at a time, they give a limited view into traffic patterns. With automatic counters, Arlington has a very good idea not only of how many cyclists use a given section of trail, but when they’re using it.

For example, on weekdays, the Custis Trail gets two traffic spikes – during the rush hours on either end of the day. On weekends, it graphs like a mountain, with usage usually peaking around late afternoon. Information like this can help guide signal timing, enforcement efforts and planning for future capacity.

Right now, Arlington has 11 counters on its trails and has just started installing bike-specific counters in some of the bike lanes along major routes. There’s a map of the counter locations here. That link will also let you access some of the past data, but it needs a bit of an update with this year’s data. Eventually, the data will be made available to the public in an almost-live feed for further parsing and analysis.

Collecting and making this data public are an important part of demonstrating that cycling really is transportation for thousands of Arlingtonians on a daily basis. It’s not a handful of cyclists who are asking for infrastructure out of proportion to their numbers. In 2010, there were 351,767 cycling trips counted on the Custis Trail. In 2011? 373,087, representing an increase of more than 20,000 cycling trips past this particular point in a single year. 

That’s not just good news, it’s hard data. So when it comes time to make decisions about our transportation infrastructure and funding? We’ll have the data to drive those decisions in favor of improving cycling in Arlington.


There will be more analysis of these numbers in the new year, once we close the books on 2012. I’ll be surprised if that particular Custis Trail counter hasn’t recorded well over 400,000 trips. It will also be interesting to see the numbers coming in from the new bike lane counters.

Mark Blacknell is a member of the Arlington Bicycle Advisory Committee, president of the Washington Area Bicyclist Association, and a League Cycling Instructor.


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