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Counting Bikes to Plan for Bikes
There is an old adage that says “you can’t manage what you don’t measure”. Arlington County planners are taking this to heart as they continue their work to make Arlington a great community for biking.
A robust program using automated counters is being rolled out throughout Arlington and the data being gathered is already providing some interesting and useful information. Technology is being utilized to provide around the clock data that will strengthen the case for investment and encouragement in bicycle transportation, and direct efforts so that they make the most impact.
Traditionally, bike trip data has come from a combination of manual counts and survey. Both methods provided limited information that was not particularly dependable and required a lot of manpower. Imagine the task of working for weeks to organize a team of volunteers, bribing them to commit to a full day of standing on a street corner observing activity and checking off bikes with a clipboard, compiling all the data, only to be frustrated by the fact that some of the volunteers did not follow directions and provided inaccurate data, or the whole day gets sabotaged by rain, making the numbers small and the counts not very useful. Similarly, survey results are often incomplete or skewed and are almost impossible to do in a manner that gives an accurate representation of reality.
The first two automated bike and pedestrian counters in Arlington were installed in the fall of 2009 on the Custis Trail and the Four Mile Run Trail. They use a combination of in-ground loop detectors and infrared beam to collect data on trail usage, both pedestrians and cyclists (ok, the occasional deer might get counted as a pedestrian also). There is a huge amount of data being collected by these counters, and it will become most useful once several years worth can be compared. Some early insights include:
- People are riding bikes on these trails – lots of them!
- People are biking on these trails to commute to and from work.
- Many cyclists are not deterred by the cold temperatures in the winter, but rain, snow and ice do have a major impact on ridership.
Figure 1: Bike Trips on Custis Trail
Click image for larger version.
Alternate content: Figure 1 graph data in HTML table
Figure 1 shows the popularity of the Custis Trail, an off-street, paved multi use pathway which runs east-west across Arlington paralleling I-66. Over 44,000 bike trips in June of 2010, with peak days close to 2,000 bike trips. Imagine if all those trips were added as vehicle trips to I66 and the other already congested roads. Biking is making a difference!
Figure 2: A.M. and P.M. Commute Hours
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Alternate content: Figure 2 graph data in HTML table
Figure 2 shows that the Custis Trail is being used heavily as a commuter route during the week. Notice the am and pm spikes, which are typical commuter travel patterns. I can verify this from my own observations on the Custis Trail, where I see most riders with backpacks or panniers during commuting hours. This sends an important message that this trail is a valuable commuting facility, and much more than a recreational trail where people go for some exercise and fresh air. This is important as facilities and projects compete for limited funding that provides improvements, expansion and general maintenance.
Figure 3: Effect of Weather
Click image for larger version.
Alternate content: Figure 3 graph data in HTML table
Figure 3 shows the effect of the weather on bike trips. Cyclists on the Custis Trail are much more averse to rain than to cold temperatures. This also strengthens the case for trail maintenance and snow clearing through the winter. If the trails are clear of snow, many people will ride despite the cold. A relatively small investment in clearing the trails keeps people on their bikes, which mean less cars on the road.
In addition to the initial 2 counters that have been up and running since the fall of 2009, Arlington now has 3 more automatic counters installed on trails around the County. Even more are coming later this year, including counters in on-street locations that will count cyclists in bike lanes. This wealth of data is extremely helpful in legitimizing cycling as a valid form of transportation, and also in guiding the efforts of transportation planners. So the next time your ride in Arlington, remember – we are “counting” on you!
