Cities are Making Left Turns Safer with ‘Wedges’

A "slow turn wedge" at 89 Avenue and 164 Street in Queens, New York. Photo: Google Maps
A "slow turn wedge" at 89 Avenue and 164 Street in Queens, New York. Photo: Google Maps

Cities are getting smarter about using design tricks to improve safety for a particularly dangerous maneuver: Left turns.

A growing number of cities are installing “slow turn wedges” and other left-turn traffic calming treatments. These treatments — typically posts placed out in the intersection — force drivers to slow down and follow the proper path while making left turns.

About a quarter of pedestrian crashes result from left-hand turns.

New York City is the leader, having installed left-turn traffic calming infrastructure in more than 200 locations in 2016 and 2017. That includes 38 “slow turn wedges” created using rubber curbs and bollards (pictured above).  These, however, can only be installed at locations between a one-way and a two-way or another one-way road.

Another tool is what New York calls a “hardened centerline” (below), where bollards prevent left-turners from crossing the centerlines to make a turn.

Hardened centerlines in New York City. Photo: David Meyer
Hardened centerlines in New York City. Photo: David Meyer

Unlike “slow turn wedges,” these can be installed at any type of intersection. Pedestrian islands can also accomplish the same goal if they are placed strategically, with the added benefit of being more durable and providing refuge for walkers.

Photo: New York City DOT
Photo: New York City DOT

This image from New York City DOT shows how these elements can be applied either together, or without the hardened centerline to impose a more controlled, slower turning motion.

Image: NYC DOT
Image: NYC DOT

According to research by NYC DOT median left turn speeds have decreased 19 percent at intersections where these treatments have been installed. And the number of vehicles crossing the double yellow lines while turning left has decreased 79 percent. The effort, part of New York’s Vision Zero campaign, is called “Don’t Cut Corners.”

In addition to the design features, New York City DOT has also banned left turns at certain high-risk locations.

Now other cities are starting to follow NYC’s lead. The National Association of City Transportation Officials is currently helping the city of San Jose install slow turn wedges in a number of locations as part of the city’s ambitious Better Bikeways program, according to a spokesperson.

In addition, there are two “slow turn wedges” in downtown L.A., inspired by New York’s example.

4thHill118May28
4th and hill Street, Los Angeles. Photo: Joe Linton/StreetsblogLA

Streetsblog LA’s Joe Linton says they work well.

“Even though there aren’t tons of locations for these — the LA locations are nearly all downtown- where the one-way streets are, and that’s where lots of people walk and take transit,” he said. “They’re great.”

Of course, there’s always a backlash from car owners who feel that safety measures are an infringement on their right to speed or drive recklessly. In New York, a recent protest by a state senator went viral when the lawmaker complained about “unsafe” pedestrian islands — while standing completely safely on one for more than two minutes.

It’s worth noting that the senator, Marty Golden, was defeated by a street-safety advocate on Election Day.

  • jcwconsult

    Simple engineering changes like these to affect left turns are fine.
    James C. Walker, National Motorists Association

  • MT

    No one needed your approval.

  • LinuxGuy

    Who is claiming a right to speed or drive recklessly as the end says? I know of no person who seeks to do these things. Seeing comments like that, if the goal is to ban cars, then just do it all at once and be done with it.

  • Ben Schumacher

    I know plenty of people who claim that right.

  • Obesa Adipose

    But you’ll never get them to admit it.

  • Ben Schumacher

    Have you met the general public in this country? They love complaining about things slowing them down and demonize anyone who infringes their “right” to drive fast and ignore traffic rules…unless someone else breaks rules that slow them down.

  • Good examples but It is interesting that everyone is more focused on obstacles and space rather than time, a critical component of safety . So let’s talk about signal timing.
    Nyc also installs a much superior solution split LPIs . First it creates a left turn lane, so thru traffic can go thru and avoid honking which puts pressure on turning drivers. it gives 7 to 15 seconds of fully protected crossing time with a red arrow, and then the balance of the cycle with a blinking yellow arrow which signals to drivers to be extra careful and the fact they do not have priority. Feels very safe And is very safe.
    On two way streets, the hardened center does not protect against the real risk since the left turning driver focuses on the incoming traffic rather than the pedestrian crossing . The only acceptable and safe solution is a split phase.
    Another feature which is critical but not applied across the board is the trailing green arrow which significantly reduces conflicts with pedestrians.

  • Bernard Finucane

    Nice start. These look cheap and effective.

  • Bernard Finucane

    Banning cars in large areas of lower Manhattan is good idea. I suspect it will happen in the near future. You should travel a bit more, and you’d see how many countries have used bans on cars to increase property values and bring life back to dead cities.

    This started in Europe in the 60s. Obviously you are just saying banning cars as way to make people sound crazy, but the fact is you are fifty years behind the times in city planning, and you have no excuse for it.

  • JackDeeRipper

    True yet it’s quite observable.

  • jcwconsult

    Two engineering changes that almost always improve safety. Protected left turns and advance pedestrian walk signals.
    http://www.trb.org/main/blurbs/178376.aspx

    James C. Walker, National Motorists Association

  • jcwconsult

    The reason that is true, and the 75+ year old proven principle in traffic safety engineering, is that posted speed limits have almost no effect on the speed ranges chosen by the slowest 85% of the drivers. If the slowest 85% are at or below 40 mph on a main multi-lane collector or arterial, they will be between 37 and 43 mph – but more likely between 38 and 42 mph – regardless of whether the numbers painted on the signs are 45,40, 35, 30, or 25. To see the largest study ever done on raising and lowering both urban and rural speed limits see http://www.biblio.org/rde/sl-irrel.html
    James C. Walker, National Motorists Association

  • LinuxGuy

    I would like to ban unwise people from having kids. That would be a great start.

  • LinuxGuy

    I doubt people set out to harm anyone.

  • Bernard Finucane

    Interestingly, the birth rate in the US fell dramatically in the last few years, and is well below the replacement rate.

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