Arlington bike data post 2 - Comparing 2009 with 2010 ridership

This is the second in a series of posts analyzing the data that Arlington County has been collecting from its automated bike and pedestrian counters.  My previous post compared ridership from 2009 to 2010.  2010 ridership was higher by 11%, but the weather may have been the deciding factor.  This post looks at the data again from a different perspective.
For this comparison I took the data for the five weeks starting in mid-October through the third week of November.  For each day of the week (Monday, Tuesday, etc.) I charted the highest ridership for that particular day.  That is, I chose the Monday with the highest ridership in 2009 and the Monday with the highest ridership in 2010 regardless of whether it was from the same week.  Five of the seven days of the week showed higher ridership in 2010 than 2009.  The total for all seven high ridership days for each year are:
  • 2009 - 9,826
  • 2010 - 10,617 (+ 8%)
It should be noted that the highest ridership day of all was actually Saturday, Oct 30, 2010 with over 1,600 cyclists.  This number was clearly an anomaly; ridership was skewed by the Stewart/Colbert rally on the mall, so I disregarded it for the sake of this analysis.

For just the five weekdays the totals are:
  • 2009 - 6,085
  • 2010 - 6,590 (+ 8%)
This analysis, which eliminates rain as a factor, shows a gain in ridership but not as much as my previous post.

I performed a separate analysis which was also intended to eliminate rain as a factor.  For this one, I took the seven weeks from mid-October through the first week of December and disregarded all days that had any rain in either year, matching up the days of the week.  There were 20 days that were completely dry in both years, and they are shown in this chart:
This analysis essentially attempts to create an apples-to-apples comparison from year to year--comparing the same days with each other and ignoring days with rain.  Total ridership for these 20 comparable days were:
  • 2009 - 15,970
  • 2010 - 16,180 (+1.3%)
This analysis, in contrast to the other two, shows only a very small gain in ridership from 2009 to 2010.   However, other factors, such as temperature, almost certainly also had an effect on the results.

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