Monday, July 27, 2015

Should Urbanists Make Only Right Turns?

I can’t find a link on the internet, but I recall a scene from “Seinfeld” where George’s parents excitedly explain that they’d begun making left turns in New York City and found it has opened whole new worlds to them.  Even I’ve remembered the wrong show, the message still stands.  Right turns may feel more comfortable and safe, but left turns can open new routes of navigation, while making the drivers feel like they’re living dangerously.

Unfortunately, the ones who are truly living dangerously are the pedestrians and bicyclists in the route of the left-turning drivers.  The rates of pedestrian and bicyclist injuries and fatalities are higher when the involved car is making a left turn rather than a right turn.

The difference is sufficiently notable that members of the New York City Council have written to Google asking if an option to request mostly right turns can be included in the direction giving function of Google Maps.  Sarah Goodyear of CityLab reports that the Council members are awaiting a response.
The request is an element of the Vision Zero program being implemented by New York City, a program with the stated goal of reducing pedestrian and bicyclist deaths to zero.  (San Francisco also has a Vision Zero program.)

Taking the left turn issue to an even higher level, Sarah Zielinski of reports on alternative intersections designs that would eliminate some of the most dangerous left turns, instead replacing them with right turns followed by u-turns.  

 The intersection configuration has been termed the “Michigan left” and is can often be an element of what the State of North Carolina calls “super streets”, streets that are intended to expedite traffic flow on the primary street at the expense of the cross streets.   North Carolina State has indeed found that super streets result in fewer accidents.  However, the concept of a super-street prioritizing one direction of traffic over the grid is so profoundly drivable suburban that I can conceive of few places where it would make sense in an urban setting.

Although not mentioned in either article, I also suspect that a well-designed roundabout, with an emphasis on the term “well-designed”, would also reduce accidents between left-turning cars and pedestrians and bicyclists, and would often be suitable in urban settings.

Personally, I’m going to continue making left turns where it’s the appropriate route, but having learned how easy it is for a left-turning driver not to see a pedestrian or cyclist, I’ll ramp up my alertness to that possibility.

Hopefully, George’s father will do the same.

Next time, I’ll offer an update on my request for support on a possible alternative location for the second Petaluma SMART station.

As always, your questions or comments will be appreciated.  Please comment below or email me.  And thanks for reading. - Dave Alden (

1 comment:

  1. Interesting. As someone who is primarily a bicycle rider, secondarily a pedestrian, and tertiarily an automobile drive in Petaluma, I am more concerned with right turns. 1. By cars overtaking me on the bike (especially when they, um, forget to signal). 2. By bikes coming up behind me when I am driving a car. I wonder how the research stats break down this....

    The lovely specter of "super-streets" make me ill. I appreciate the heads-up!