Comparing Bike Traffic on the Custis Trail - New Data Loggers Provide Great Data

Since the fall of 2009, Arlington County has been automatically collecting data from dedicated bike and pedestrian counters.  The counter on the Custis Trail at the top of the Rosslyn hill near mile post 3.5 (map) has collected the most data--tracking at 15 minute intervals continuously for more than 15 months.  Data has also been collected from the other counter that is located on the Four-Mile Run Trail east of Shirlington near the new I-395 underpass.  I will analyze other data form these counters in future blogs.  Arlington is continuing to add more counters, which will allow for very rich and useful data.

Bike Arlington reported on the CommuterPage blog that data from these counters will be available online with graphing tools allowing one to do their own analysis.

For my first analysis, I compare bike traffic on the trail between 2009 and 2010 (click for larger version).

I compared 5 weeks starting at the first of November through the first week of December.  For the graph, I aligned the days of the week (so 2010 actually starts on Sunday, October 31).  Total ridership over the 5-week period was:

• 2009 - 24,015
• 2010 - 26,714 (+11.2%)

That's a pretty good bump for one year.  However, it turns out that 2009 had a lot more rain.  Thanks to David Patton, Transportation Planner for Arlington County, who created an initial chart superimposing rain with ridership for November 2009, I took his idea a little further.  The chart above shows days with rain as darker bars.  2009 had 13 days of significant rain and 3 days with tiny rain.  2010, however, had only 5 days with significant rain and another 7 with a tiny bit of rain.  I do not know what time of day the rain occurred.  So it's hard to know if the increase from '09 to '10 was due to weather, other factors or an actual increase in ridership in general.  On my next post I am going to attempt to remove that variable to see what happens.