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Measuring Cycling Growth

Bike Walk Twin Cities released their official 2011 bike and pedestrian counts today. BWTC presented the new data, along with annual counts dating back to 2007.

The bicycle counts clearly show a general increasing trend in 2011 compared to previous years. This is good news, since the Federal mandate attached to the $28 million NTPP funds administered by BWTC received was to demonstrate that increased investment in bicycle and pedestrian infrastructure will result in increased rates of bicycling and walking. These numbers have gotten a lot of press today, and the big headline grabbing statistic is summed up by this tweet from BWTC:

In the Twin Cities, #bicycling is up 53% and #walking is up 18% from 2007-2011! #bikefact #hotdamn

So does the data released today demonstrate that BWTC has met their mandate?

Not quite, but it’s a step in the right direction. Here are a few things to keep in mind before drawing any conclusions based on the data released today:

  • Rates not Numbers – the Federal mandate is to demonstrate increased cycling rates, not just an increase in overall number of people cycling. This data must be compared to the number of trips made using other modes before we can know if the cycling rate has increased. This raises other questions. Do we compare to regional Vehicle Miles Traveled? Do we compare on a project-by-project basis? This shouldn’t be much of a problem since all indications are that we have reached “peak travel” (at least until the economy recovers).
  • Inconsistent Growth – A growth of 53% over four years is pretty impressive, and it makes a great headline, but the data clearly shows this growth hasn’t been linear (despite the linear trendline BWTC has drawn on the chart). Most of this growth occurred between the 2007 and 2008 counts. An understanding of the history of BWTC calls into question whether we can attribute this growth to the investment of NTPP funds. The NTPP program was created in 2005 but it didn’t really get moving until 2007. BWTC’s first funding solicitation was in 2007 when a number of planning, advocacy, educational, and infrastructure projects were funded. However, projects move slowly, especially infrastructure projects, the majority of which would take several years of development before resulting in changes on the ground. We may need to consider the possibility that a substantial portion of this growth should be attributed to other factors (two possibilities including the economic downturn and rising gas prices). How do we account for the large growth in 2008, followed by two years of declining counts before another large jump in 2011? Is it just noise in the data? Or are there other factors influencing cycling rates?
  • Control Group – We also need to compare any growth in cycling that happens in the Twin Cities with growth happening in other communities – communities that aren’t recipients of NTPP funds (and communities that haven’t spent their own – or somebody else’s – money on bicycle infrastructure). Cycling is becoming more popular everywhere, and we need to consider the possibility that even communities that aren’t investing in cycling infrastructure may be seeing an increase in riders.
  • Route Consolidation – One of the biggest criticisms of bike counts is that its very difficult to control for route consolidation. If we see an increase in the number of cyclists in a location where new infrastructure has been constructed, how do we know we’re observing new riders, not riders who previously were using other routes? One of the only ways to control for this is by observing bike counts at all other potential routes. BWTC has published counts at 42 locations, which seems like it should be sufficient,  but there are still unanswered questions about route consolidation. For example, between 2007 and 2008, there were an additional 536 cycles across the Sabo Bridge/ 28th Street Crosswalk. Surely not all of these cyclists are new riders. Many were undoubtedly using other routes to avoid having to use the 28th Street Crosswalk. Similarly with the hundreds of riders counted using the new extension of the Cedar Lake Trail through downtown Minneapolis. Another example: The data shows a 24% growth in the number of cyclists using the Loring Bikeway Bridge, but a 15% decrease in the number of cyclists using the next best alternative if the Loring Bikeway Bridge didn’t exist – cycling directly on Lyndale Avenue north of Franklin Avenue. How do we know that the new riders using the Loring Bikeway Bridge aren’t the same riders that used to be using Lyndale Avenue? How do we know that the growth observed at specific locations represents new riders, not just consolidating riders from many routes onto fewer routes (this may or may not still justify investment, but that’s another post).

All this being said, the new results are a very positive indication that the funding provided by NTPP is having a positive impact on cycling in the Twin Cities.

What do you think of the new data released? Do you think it demonstrates that investment results in new riders?

2 comments to Measuring Cycling Growth

  • Another potential issue is the basic validity of the data. My understanding is that most of the counts are derived by having volunteers stand at each location and count for a two-hour period 4pm-6pm on a single weekday in September. I completely understand that this is probably the best that can be done with limited resources, but I also would be hesitant to use this very limited snapshot to infer trends like “bicycling is up 53%” or “NTP successfully increased bicycle mode share.”

  • @Spencer – Yes. Agree completely.