“Bikeable Cities” and Bike Lanes

Posted on May 19, 2012 · Posted in Commuting, Roads

Seattle was recently ranked #7 in the nation for “bikeability.”  While we can all collectively pat ourselves on the back or bemoan the fact that we finished behind DC and Minneapolis, I was interested in the methodology used.  According to the Walkscore folks who put it together, the “bikeability” rating of a community is based on four equally-weighted factors: Hilliness, bike lanes, road connective and bike commuting mode share.

I guess Seattle’s always going to be in a hole compared to DC & Minneapolis when it comes to hilliness.

Having a fair bit of familiarity myself with the ins-and-outs of rating the intangible, I’m impressed with the thought that went into the Bike Score rating methodology.  For instance, check out how bike lanes are dealt with:

Bike lanes are divided into four categories: on-street bike lanes, off-street trails, cycletracks (separated bike lanes), and residential bikeways (a.k.a. bike friendly streets or greenways).

While examining the data, there were variations in how cities reported their infrastructure, especially with regard to residential bikeways. In cities like Vancouver, residential bikeways are bike priority streets with traffic calming, signage, and on-street markings. In some US cities, a residential bikeway might have very little infrastructure. Because of these, we collapsed the four bike path categories into two categories, on-street and off-street.

For a given location, we sum up the length of all nearby bike lanes. We apply a distance decay function to each segment, where no value is given to segments further than 1,000 meters from the origin. We weight off-street lanes 2X as valuable as on-street lanes. This creates a raw value that we normalize to a score between 0 – 100 based on an average of the highest Bike Lane Scores that we sampled.

Obviously there is a wide variation in the quality of bike lanes, and it’s great to see that the Walkscore guys are accounting for the differential between on- and off-street lanes.  However, seeing this recent tragic news out of Portland about a cyclist dying in a right-hook collision while riding in a bike lane, I have to wonder if on-street lanes should count at all – or if they should carry a negative weight.

The problem is that many urban on-street lanes are poorly-designed.  They put riders in the door zone, require swerving around double-parked trucks, dealing with buses crossing the lane mid-block to meet stops, and offer no bail-out options if a clueless pedestrian steps off the curb.  They also reduce visibility while simultaneously raising cyclist complacency that they are safe in “their” lane.

This is why I often don’t ride in bike lanes, preferring to take the whole lane for safety’s sake – and why I find that some of the lanes (like Pine Street downhill – photo above) don’t contribute at all to the “bikeability” of my city.