Learning About Bicycle Commuters
Metro is trying to triple the number of bicyclists accessing our transit services by 2020. Our Bicycle & Pedestrian Access Improvements Study showed that although bicycling represents a small portion of station access now, this mode has very strong potential for growth. For example, many of our parking customers live less than 3 miles from their rail station, and many parking facilities fill up between 7:45 and 8:30 am.
As part of this campaign, we are trying to learn more about the travel patterns of bicyclists so that we can better plan facilities and services for them. For example, how strong is the “seasonal” effect in biking? What time of day do cyclists ride? How does bicycling demand patterns compare to our rail and bus networks?
One source of data for these questions is the automatic bicycle counters that Arlington County has installed on the Custis Trail, a major trail for bicyclists between downtown, Arlington, and points west. This counter can sense the difference between a bicyclist and a pedestrian, and has been silently counting both since October 2009. The counter is located at the top of the hill between Rosslyn and Courthouse (map). Previous analyses of this data are available online.
While Custis Trail users certainly don’t necessarily represent current or potential bike-to-rail customers, they do provide some data-driven insight into the travel demand of bicyclists, whom we hope will be a key part to Metro’s long-term strategies for rail access. So, the rest of this post analyzes bicycle counts by 15-minute intervals between October 2009 and February 2011.
Markers on the graph below are individual days, and the solid lines show a rolling 2-week average to smooth out the patterns and to compensate for weekends. Bicycling on the Custis reaches its height by about April, stays constant until mid-October, and then drops by December through February. March and November are the shoulders. Demand is not zero even in the coldest months – average “low season” demand is about a third of “high season.” There is no appreciable drop in bicycling even during the hottest months in the summer, as others have noted too.
This data also show that over the course of a year, the winter results in a loss of total bicycle trips of around 30%. That is, if demand stayed at its “high season” rate all year round, annual bike trips on the Custis Trail would be about 30% higher. This metric captures both the duration and the magnitude of the winter effect.
The dispersion of the dots in the graph show that bicycling demand is fairly variable on a day-to-day basis. Bicycling demand on the Custis Trail appears to be relatively more variable than the day-to-day consistency we typically see on Metro transit services.
The string of red zeroes in February 2010 show when the trail was covered in snow and ice and impassable for 2-3 weeks following two blizzards. Interestingly, during the same stretch in February 2011, the trail saw about 500 bicyclists per day. In total February 2010 was about 10,000 bike trips less than February 2011.
Metro sees seasonal effects on its bus and rail services, as well, for weather and other reasons (holidays, tourism, etc). But, the “winter effect” is not nearly as high, for obvious reasons!
The next two graphs show a low, median, and high day by 15-minute intervals, out of about 500 days. Showing the median and then 25th and 75th percentiles gives us a reasonable range of normalcy. The really miserable cold or icy days, and also the spectacular, popular summer days aren’t shown here – this is the middle half. A few observations:
- Weekday bicyclists on the Custis Trail show a strongly-peaked commuter pattern.
- The morning peak is concentrated from 7:30 to 9am.
- Peak weekday bike demand is strong and steady. On good days (75th percentile, dark red below), the trail sustains an average flow of one bike every 20 seconds, or about 200 bicyclists per hour for about an hour between 7:30 and 8:30am, and then again between 5:15 and 6:15pm.
- Even throughout midday lull, there is on average one bike every 3 minutes on the trail
- On the below-average (25 percentile) days, presumably more often in winter, the morning peak is later, and the afternoon peak is earlier. This is probably due to the temperatures and sunlight in the winter. In the summer, bicycle commuters tend to lengthen their commutes, and the peaks shift to earlier and later in the day.
Time-of-Day Comparisons to Rail
- Bicyclists on the Custis appear to have similar “peaking” characteristics as rail passengers, although on a much smaller scale. Bicyclists on the Custis want to travel at similar times as Metrorail passengers.
- Bicycle commuting on the Custis reaches peak at around 8:15 – 8:30 am, which is slightly after many Metro parking facilities fill up (on average between 7:45am and 8:30am, depending on the station, not shown on the graph below), but slightly earlier than what the rail network experiences.
- Peak demand is 5 or 6 times midday demand – we experience a similar ratio (although slightly lower) on the rail system.
The last chart shows total bicycles per day on a median day, by day of the week and by “high” and “low” seasons. On weekends in the summer, weekend totals are nearly as high as weekdays. In the winter, hardy weekday bicycle commuters appear to outnumber weekend riders. All weekdays appear to be more or less indistinguishable in terms of bicycle ridership, which is similar to the rail network. However, Fridays are often noticeably different from Monday-Thursdays on the rail network.
Implications for Metro
So what does this mean for Metro as we plan bicycle facilities and try to increase bicycle access to our services?
- Bicycle demand is out there, and it can be strong.
- Plan and size bicycle facilities based on peak demand. Hot weather does not suppress demand, and cold weather suppresses only 30% of annual trips.
- Measure bicycle demand across several days between mid-April and mid-October. Bicycle demand is relatively variable day-to-day – we can see significantly higher biking on a good (75th percentile) day compared to a median day.
- Bicycle commuters have similar temporal patterns of demand as our transit passengers.
- Provide sufficient space and security for bicycle parking. Because bicycling “peaks” after our parking facilities fill up, bicycling can help our customers who want to access the rail network but don’t want arrive at a station early in the morning.
- Keep bicycle access paths clear of snow and ice. Some bicyclists want to ride, and will ride in the winter – if we tend to the facilities.
- Weekend bicyclists may represent just as large a market as weekday commuters in the summer, but they are spread throughout the midday.
What do you think this data means for Metro? What did we miss?