Finding a new way to measure cities’ bike friendliness in the United States

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A really smart person could come up with a way to measure day-to-day bike friendliness based on how well cities adhere to standards that keep roads clear of obstructions that further frustrate the commute, like construction projects that squeeze bikes and cars together. 

I work at home. There are some days when I only leave my house to get milk from the Mexican grocery store at the end of my block (which makes awesome burritos). That means I ride my bike half as much as people who commute to work. on their bikes. Today I had a bunch of errands to run: drop off stuff, buy stuff, take pictures of stuff for my blog, Grid Chicago.

It was a very frustrating experience. I don’t need to go into details about how I was harassed by people who the state so graciously awarded a license to drive. But it happened. And it happens a hundred times a day to people cycle commuting in Chicago. I got to thinking about “bike friendly” cities. Is there a way to incorporate driver attitudes in there? I tweeted:

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Later I had the idea to use some very simple but objective measurements to create a new bike friendliness metric. It would help ensure that “Silver” (a ranking the League of American Bicyclists [LAB] uses) in one city means the same as “Silver”. It can expand from here but basically it works like this:

  • The share of people going to work who go by bike is a proxy for how “friendly” a city is to biking.
  • If a city has a lot of people biking to work, it must be friendly.
  • If a city has a few people biking to work, it must be non-friendly.
  • Cities are compared to each other to determine friendly and non-friendly.
  • The metric uses standard deviation to score cities.

Stop me if this has already been done.

I created a spreadsheet that lists the top 10 populous cities in the United States. I then added 10 more cities: Austin, Boston, Davis, Madison, Minneapolis, Portland, San Francisco, Seattle, and Washington, D.C. In the next column I listed their bike commute share from the American Community Survey 2006-2010 5-year estimates. I calculated the standard deviation and mean of these shares and then in another column used Apple Numbers’s STANDARDIZE function:

The STANDARDIZE function returns a normalized value from a distribution characterized by a given mean and standard deviation.

I think that’s what I want. And the output is close to what I expected. I then found the LAB ranking for each city and found the variance of each ranking to see how far apart each city within one ranking was from another city in the same ranking. The results were interesting: the higher the ranking, the more variance there was.

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Hurricane Sandy prompted a lot of New Yorkers to bike. It made headlines, even. Photo by Doug Gordon. 

I wanted to add another metric of bike friendliness, and that’s density. To me, a higher density of people would mean a higher density of places to go (shop, eat, learn, enjoy) and friends and family would be closer, too. Or the possibility of meeting new people nearby would be higher. Yeah, I’m making a lot of assumptions here. So I applied the STANDARDIZE function there as well. I added this number to the previous STANDARDIZE result and that became the city’s score.

So, in this new, weird ranking system, the most bicycle friendly cities are…drum roll please…

  1. Davis, California (Platinum)
  2. New York City (Silver) *
  3. San Francisco (Gold) *
  4. Boulder (Platinum)
  5. Boston (Silver)
  6. Philadelphia (Silver)
  7. Tie: Chicago*, Washington, D.C. (Silver)
  8. Tie: Portland* (Platinum), Minneapolis* (Gold)

Remember, I said above that any author of a list should spend at least a day cycling in each city. I’ve starred the cities where I’ve done that – I’ve cycled in 5 cities for at least a day.

I only calculated 20 cities. Ideally I’d calculate it for the top 50 most populous cities AND for every city that’s been ranked by LAB.

LAB cities list (PDF). My spreadsheet (XLS).

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About Steven Vance

Enthusiast for urbanism, bicycling as transportation, and open data. Building a bicycle culture in Chicago.
  • John

    I like the simplicity of using commute mode share, but it’s not at all clear to me what your STANDARDIZE function is doing. It makes sense though that a bike friendly city attracts more bike commuters. Density makes some sense to include the non-work trips, but I have found little to no statistically significant relationship between density and work trip mode share in Chicago, after controlling for other factors.

    • http://www.stevevance.net/ Steven Vance

      Yeah, I know what you mean… I need to look more into what the STANDARDIZE function is doing. What I tried to do with a manual formula is calculate how many standard deviations each figure was from the mean. I think I created a good formula, but it didn’t work in all cases. I then found the formula and its output was very similar to my manual formula.
      I’m going to update this post or make a new one and publish the “raw” data that I used to calculate this. I have some other data from CMAP’s Travel Tracker (look in my latest post on this blog) that’s for all trips (in trip frequency and in trip distance) that I could use in addition to or in place of density. I still like density but I would prefer another metric that better describes dispersion of desirable and common business/retail uses.
      I used density and assume the more dense a city is, the more destinations that will be nearby, and I assume that bike trips are shorter than other trips making things nearby “more bikeable”. So this measurement of bike friendliness assumes a lot, but I think it gives a more accurate measurement to compare cities than nominal rankings.
      I don’t think any bike friendliness measurement really needs more than current, existing trip mode share. If your city is bike friendly, then you will have more people out biking than one that’s not. The number of people who bike is all you need to know if you’re a bike friendly city. I don’t know how to make this more clear. However, this measurement system doesn’t indicate how a city can become more bike friendly/get more people to bike to work. For that, they can just look at what cities with higher scores are doing!

  • http://twitter.com/FiveStarRlty Five Star Realty

    TEAM Punta Gorda, a grassroots group formed to help rebuild Punta Gorda, Florida after the devastation of Hurricane Charley in August 2004, recently implemented a bicycle loaner program that allows anyone who is interested to borrow a canary yellow bicycle from various locations in Punta Gorda and ride it around town. (More Information: http://www.teampuntagorda.org/bicycleloaner.html)

    This works well with the CIty of Punta Gorda’s Ring Around the City, a 18 mile system of pedestrian and bicycle paths and trails scheduled to be completed in the next few years. (To learn more. visit: http://www.ci.punta-gorda.fl.us/depts/growthmgmt/ringaroundcity.html)

    Considering Punta Gorda, Florida has a population of under 17,000, how “bike-friendly” would you consider that city to be?

    • http://www.stevevance.net/ Steven Vance

      I’m not sure that city’s bike commute share would even be measured because it’s population is too small. But let me check…Ah, it’s here!
      The commuting mode share for bicycling is 0.0% with a huge margin of error because the sample size is so small. So I can’t place it into my ranking system.