Has there been an increase in biking in Arlington due to Washington D.C.’s region-wide SafeTrack initiative to repair Metrorail? It’s a difficult question to answer at this point.
BikeArlington has already reported that there were increases up to 75 percent over 2015 daily averages in bike traffic at the Rosslyn-Custis Trail bike counter during the first surge back in June 2016.
How much were this and other increases caused by SafeTrack or simply a product of a trend of bicycle traffic building up steadily over the years?
I took a look back at 2013, 2014, and 2015 data (see the graphs I created at the bottom of this article) in order to compare cycling daily averages from these times to the SafeTrack surge averages in 2016 and 2017. I controlled for weather to some extent, since it has such a significant impact on cycling and walking.
It seems that the only major difference from previous analyses is that increases in later surges are attributable to trends over the years of increasing winter ridership.
For the Surge 8 through 11 time period (in 2016, from August 27 to December 20), trail use had shown a decrease over the same time period from 2013 to 2014, but then it steadily increased after 2014 (except during Surge 9 on the Mount Vernon Trail). This could be attributed to some of the increase in winter ridership during SafeTrack to overall increasing trail use since 2014.
Ideally, this is the desired effect too. As transportation options become more plentiful and more well known, it makes sense that, over the years, cycling numbers increase.
Looking at the Surge 12 (which ended in February 2017) time period, however, all previous years showed a decreasing trend, with the SafeTrack surge creating quite an increase in ridership, going above even the 2013 numbers. Part of this can be attributed to an unseasonably warm February.
How much of this increase can be attributed to SafeTrack versus summer-like weather?
In the fall, trends stay fairly steady. SafeTrack caused quite an increase in traffic, and David Patton, Arlington County’s bicycle and pedestrian planner, says, “[Over] seven years of data for [the Custis Rosslyn bike counter], there is about a 3.5 percent compounded increase [for bikes]. It’s not a straight line – highly conditioned by weather – but on a slow upward trend.”
Henry Dunbar, program director of Bike Arlington, added, “It’s really difficult to pinpoint how much direct effect SafeTrack had on bike ridership. A lot of the original mode switching likely went back to riding Metro after the early surges proved to be not that disruptive, but we won’t know for certain until some more in-depth surveys are done. For now, the bike counter data alone can only tell us so much.”
The pattern over the years is very curious too: decreasing ridership in the summer, followed by stable ridership in the fall, and increasing ridership in the winter, until January.
Stable and increasing ridership are understandable, as Americans become more multi-modal.
The decreasing summer trends are questionable, also because they are not steadily decreasing. This means that there could be an anomaly in one of the years that is causing this shift. Is it really decreasing as people choose not to bike, or is it all due to external factors not accounted for?
The patterns surrounding Surge 12 are quite curious as well. The initial surge was thought to have caused such a large increase due to its novelty, but Surge 12 has none of this novelty, and compares in magnitude to the increase of Surge 1.
“This is interesting,” said Dunbar. “I have to wonder if that wasn’t aided by a stretch of really nice weather.”
Photo: Capital Bikeshare user in Arlington by DOT DC; Graphics by Angela Urban.