Are bike paths too dangerous?

August 31, 2009

Richfield -- 76th Street I recently came across an excellent blog on redevelopment along 76th Street in Richfield (South Minneapolis). Richfield is an unusual kind of city for today, a suburb built on an urban grid — a grid that could serve nonmotorized uses very well — but missing one critical piece of a vital city: sidewalks.

While Richfield has had somewhat of a change of heart since it was originally laid out, retrofitting unsidewalked streets can always be difficult. The solution proposed by the consultants for 76th Street was a beefy 10′ shared-use path along one side, designed to handle all nonmotorized users of the road. This post does an excellent job of pointing out issues with sidewalks and shared-use paths. (Note that this excerpt treats the two as synonymous; Northfield considers a sidewalk to be 6-10′ wide and made of concrete; a shared-used path would be asphalt and 10-12′).

The problem with [the 75th/76th Street plans] is the belief that sidewalks are safer than streets for biking. Bicycle side paths such as the one on 75th have proved so dangerous that even the US government instructs that they be used in only the few locations where their dangers are insignificant. The problem is not just pedestrians; urban sidepaths cause difficult and dangerous car-bike conflicts at every driveway and intersection. How so?

A car backing down a driveway will slow down at street level before entering expecting fast moving vehicles. This is not the case for a sidewalk. Not seeing pedestrians the car will back out past the sidewalk to the street .

A car is more likely to see a bicyclist in the street when making a right hand turn but is less likely to see the bicyclist up on the sidewalk entering in to the street when making the turn.

The author goes on to back up the claim with solid numbers, which the Task Force has also discussed in the past:

Contrary to intuition, cyclists riding on bicycle paths (now called “shared use paths”) have a higher crash rate than cyclists riding on roads, although not as high a crash rate as cyclists riding on sidewalks (Aultman-Hall and Kaltenecker 1998). The risk of injuries on paths compared to roads has been calculated as 40%, 80%, and 260% higher (Moritz 1998, Aultman-Hall and Kaltenecker 1998, Kaplan 1976).

Northfield’s Uses

Though fine for recreational use, the frequent street crossings make the shared-use path unsuitable for bike transportation

This picture -- on East Woodley -- is an example of excessive path/road crossings, creating more opportunities for accidents with turning drivers

The Northfield Parks/Trail Plan proposes several shared-use paths on streets without bike lanes: Jefferson Parkway, South Division Street, Rice County 1, and 7th Street.

Good Uses

I think that shared-use paths are only appropriate in situations where most bicyclists cannot safely interact with traffic. Rice County 1 and Division Street (MN 246) south of Jefferson Parkway are two instances where this may be the case: both are 45+ mph roads that carry around 4000 cars a day. Both also have relatively few driveways and intersections, so the risks pertaining to shared-use paths are less severe. While an ideal solution (from a nonmotorized perspective) would be to simply slow down the roads, shared-use paths are a good solution to an inhospitable road.

Bad Uses

A bad use would be unnecessarily segregating motorized and nonmotorized traffic, or putting a path where there are frequent intersections or driveways. A 7th Street shared-use path would then probably be the most questionable, since the street handles relatively little vehicle traffic at only 30 mph and is lousy with driveways. Jefferson Parkway — like Woodley Street, which just received a shared-use path — is somewhere in-between. It’s a high-traffic road with no driveways and a fairly low speed (30 mph posted; I would guess 30-35 in practice). It could have a shared-use path with somewhat lower risk, but there’s no obvious reason why it could not have a bike path instead.

Who Benefits?

Ostensibly, the beneficiaries of a shared-use path would be casual riders, but for truly inexperienced users (e.g., kids learning to bike), there’s little a shared-use path can do that a sidewalk can’t. I think the real beneficiaries are drivers, who avoid having to interact with cyclists in the same way they would have to in a bike path.

Of course, interactions are inevitable, and if more of those interactions result in accidents, nobody really wins.