Friday, July 26, 2013

One-way to higher traffic accidents?

I don't want this bit of city-traffic-related news to get lost in the recent deluge of news about Charlotte's airport. The numbers raise a question, in my mind at least, about the safety of one-way streets uptown.

Earlier this month Charlotte's Department of Transportation released its annual list of High Accident Locations. To see it, download it here. (Be sure to notice what it does and doesn't measure; for instance it doesn't measure traffic accidents on interstate highways.) The report drew a news article in  The Charlotte Observer, "Report: Charlotte traffic collisions down; fatalities up."

Here's what I noticed: Among the Top 10 high accident locations, seven were either uptown or nearby. Of those seven, all but one involved one-way streets. The only one of those seven that did not was East Seventh Street and Hawthorne Lane, in the Elizabeth neighborhood.

The city's top high accident location was Cambridge Commons Drive and Harrisburg Road (average daily traffic of 15,000), in east Charlotte near I-485, with a three-year total of 49 accidents and a crash rate (a formula taking into account the traffic volume - to know more download the report) of 2.98.

Other in-town streets:
2. North College Street and East Eighth Street.
3. North College Street and East Ninth Street.
5. Third-fourth Connector Street and East Fourth Street at Kings Drive.
7. East Seventh Street and Hawthorne Lane.
8. South Church Street and West Hill Street and the ramp to West Belk Freeway.
9. East Seventh and North College Street.

If you're thinking that correlation (one-way streets and high number of accidents) does not equal causation, of course you are right. The streets were converted to one-way years ago by traffic engineers who wanted to get vehicles into and out of uptown as efficiently as possible. That was the thinking several decades ago. So busy streets are going to have more accidents.

But the crash rate takes the street's business into account. What else might account for the striking number of uptown one-way streets that are atop the high accident list? Could it be speed? Could it be people driving home from work and just not taking as much care? (The report also shows that mid- to late afternoon rush hour is the time of day with more accidents.)

But notice something interesting: The No. 11 High Accident Location was  East Fifth Street and North Caldwell Street. Notice the accident numbers over three years: 10 in 2010, 11 in 2011 but dropping to 6  in 2012.  That intersection used to be where two one-way streets crossed. But from Fifth Street south, Caldwell has been converted to two-way. Did that cause the lower number of accidents in 2012?

I've emailed CDOT Director Danny Pleasant, to see if he had comments.  I'll add them if he responds.


Jack Kiser said...

I have often wondered if there is a greater liklihood of pedestrian hits on one-way streets where pedestrians step off the curb first into a lane where traffic is coming from the right instead of the left as it would in a standard bi-directional street. You know the old rule: Look left, then right, then left again. If you are stepping off first into the left lane of one-way street the rule is the opposite and counter-intuitive. If you ever go to London in the city center where there are a lot of tourists from countries that drive on the right, you will see printed on the curbs at cross walks: Look Right First! They may have history of ped hits due to the same factor. On one-way streets,traffic coming first from the right, and at typically higher speeds would seems to be lethal to pedestrians.

Mary Newsom said...

Jack, that's an excellent point. I have nearly been killed many times in London because so much of the traffic there is counter-intuitive. And your note reminds me to try, again, for comments from CDOT.

Anonymous said...

Hi Mary. I'm following up on this... any chance you ever received comments from CDOT? In particular, I'd love to know if the result in your observation is promising future reconsideration of the one-way network in Uptown. Many cities are recently embarking on this (see recent Planetizen article:

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