Wednesday, September 10, 2008

On-street parking tradeoffs...

I'm still trying to decide what to think about the proposal to eliminate on-street parking from our residential street (High Street in Amherst). I'm concerned about safety. I don't really care about the parking; we never park on the street, and have plenty of parking for guests, except for the rare occasions we host a large party. If eliminating on-street parking makes the street significantly safer, then I think it's a good idea.

My bleg (that's the cutsie word for "blog-beg") asking if somebody would figure it out for me didn't work, so I found a nice meta-study published in the American Journal of Public Health that passes all of the skeptical tests for information quality-- it's a peer-reviewed scientifically rigorous study published in a respected journal.

What I've learned: it's complicated. Speed is the most important factor:
The British Department of Transport, for example, finds that the risk of pedestrian death in crashes rises from 5% at 20mph to 45% at 30mph and 85% at 40mph (source)
But visibility is also important-- children get killed when they dart out from behind parked cars and get hit by drivers who don't see them in time.

Sidewalks are also important-- they reduce accidents-- and High Street already has a sidewalk on the west side of the street, which is the same side of the street where parking is currently allowed.

If I was a traffic engineer, maybe I'd be able to dig up odds ratios for all the various factors and actually calculate the tradeoffs-- but I'm pretty sure, given all the traffic calming information I was able to dig up via google (see, for example, this paper), that eliminating parking on High Street will make it more dangerous.

No comments: