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MBA: Road Diet

What’s a road diet? Quite simply, traffic-calming expert Dan Burden told Streetfilms, “A road diet is anytime you take any lane out of a road.”

The first time people hear about a road diet, their initial reaction likely goes something like this: “How can removing lanes improve my neighborhood and not cause traffic backups?” It seems counterintuitive, but taking away lanes can actually help traffic flow smoother while improving safety for everyone.

Road diets are good for pedestrians: They reduce speeding and make vehicle movements more predictable while shortening crossing distances, usually through curb extensions or center median islands. They’re good for cyclists: Many road diets shift space from car lanes to create bike lanes. They’re good for drivers: Less speeding improves safety for motorists and passengers, and providing left-turn pockets allows through traffic to proceed without shifting lanes or waiting behind turning vehicles.

And here’s something to keep in mind during this era of lean budgets: Road diets are a highly-effective infrastructure improvement that can be implemented quickly and at low cost.

Streetfilms would like to thank The Fund for the Environment & Urban Life for making this series possible.

<br> <p><font size="3" face="Times New Roman">[music]</font> <br></p> <p><font size="3" face="Times New Roman"><i>Dan Burden:</i>  [00:11] A road diet is anytime we take any lane out of a road.  If you have, say, four lanes and you knock it down to just two lanes, you’ve put the road on a diet.  I first coined the phrase and used it in 1996 in an article that Peter Lagerwey and I wrote together.  It had sticking power, people liked the term, they could understand what it meant.  The most common road diet is converting four lanes to two and then putting in the third lane for turning.  And then with the extra space adding in bike lanes.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Mike Sallaberry:</i>  [00:43] It’s a way to reallocate space so the street performs more efficiently.  And it also allows spaces to be allocated for bicycle/pedestrian measures.  As a motorist you have fewer lane changes and you now have a dedicated left turn pocket, so when you want to make a left turn, you have the space to do that and you don’t feel any pressure from behind to hurry up.  And that improves safety for the motorist and pedestrians who are crossing the crosswalks.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Charles Gandy:</i>  [01:06] We’ve reallocated the space in the street to accommodate those that live here, that work here, that buy things here versus privileging those that would just drive through here fast.  We used to have a sidewalk where the curb went right through here.  We extended it all the way out, so we still have through two car travel lanes here, but we’ve shortened the distance for pedestrians by about 50%.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Dan Burden:</i>  [01:28] When you have a road diet, typically you have one lane in each direction, and now the prudent driver is setting the speed and not the imprudent driver.  So crashes come down.  Another real benefit is it makes it much easier to get across the street if you’re a pedestrian, you end up with less distance to cross.  It’s quieter, and you end up with more people walking and bicycling.  We typically see more people socialising.  And generally we see the value of properties going up.  One city that’s way out in front of other cities is San Francisco.</font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Mike Sallaberry:</i>  [01:59] San Francisco is up to about 40 road diets, which I believe is the most of any North American city.  We have all sorts of road diets where we went from four lanes to three, three to two.  We are working on one that goes from six to four.  Back in the 1990’s Valencia Street was a four lane roadway and the Bicycle Coalition in particular wanted to have a bicycle facility on this street because it was already very heavily used by bicyclists.  So the bike lanes went in as a trial.  We went from four to three lanes with bike lanes and there is a report rate and after one year, we found that the number of cyclists increased by about 140%.  And we were finding that the emergence along the roadway were actually very open to the idea of keeping the road diet.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Dan Burden:</i>  [02:38] After the road diets go in, because motorists are driving more prudent, people can shop for parking spaces, and the retail life of the street also improves.  So the businesses typically do better after a road diet.  To a lot of people it’s a surprise if you take half of something away, the number of lanes, that you actually end up with more performance for a street.  And it just simply gets right down to the crunch of the numbers.  In science, if you have fewer of something, it can be more efficient.</font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Mike Sallaberry:</i>  [03:08] Road diet is one of the most cost efficient ways to improve a roadway.  You can do a mile of roadway for about $50,000, which is the cost of one sidewalk bulb out, or to compare it, a traffic signal could cost $300,000 or $400,000.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Dan Burden:</i>  [03:23] So we’re in New Haven looking at some roadways that are way overbuilt.  We’ve got, as you can see, the road’s empty a lot of the time, and then all of this space in between these two roads on either side was at one time all housing, and they bulldozed all of it in order to put a freeway in.  Well the freeway never came, never will come, and now we still have these very fast, very wide streets.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Speaker:</i>  [03:51] Earlier we were recording some cars that were going 50 miles an hour down this corridor.  </font></p> <p> <br></p> <p><font size="3" face="Times New Roman"></font></p> <p><font size="3" face="Times New Roman"><i>Dan Burden:</i>  [03:56] One major reason for road diets is safety.  We’ve had several people killed within a block of right where we’re standing now, doctors who work here in the hospital.  So we’re really looking at all the ways we can get out those lanes we no longer need, which when you have too many lanes you induce more speeding and more risky behaviour.  As we’re making the move back to cities, as people want to live more and more in cities, so many of the streets in our cities, 30, sometimes 40% of the streets could operate better with fewer lanes.  And otherwise change the street back to a quieter version of its former self.  And it’s working.</font> <br></p> <p><font size="3" face="Times New Roman">[music]</font> <br></p> Transcription Sponsored by: <a href="http://transcriptdivas.com.au">Transcript Divas Transcription Services</a>
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  • http://twitter.com/bmdesignhki Asko Kauppi

    Welcome New United States of America!

    I knew you were able to make it.

  • http://tiny.cc/fiubike Brandt Absolu

    Amazing video. I wish Miami-Dade County cared about calming our streets.

  • Todd Scott

    Dan Burden rocks.

  • http://twitter.com/AgentAkit Akit

    I like this idea. In San Francisco, 25th Avenue in the Outer Richmond district used to be a four lane road, and the lanes were so narrow, you feared hitting a parked car, plus the bus usually had to takeover two lanes due to its width.

    Thanks to this road diet concept, it's now two lanes with a left turn median. Traffic hasn't been affected by it, and there's no fear of hitting a parked car anymore.

  • http://profiles.google.com/subtle116 dave “paco” abraham

    one of the best streetsfilms yet. nice job... very easy to digest for even those who've never heard of traffic calming.

  • Clarencia

    We'll keep trying to make them easier and easier to understand! Thanks Paco.

  • concerned citizen

    This is a stupid idea for our town, Stuart, Florida. There are no access roads to Stuart now, and the ones we have are too short and dead end into a railroad track which closes at least 28 times a day. We are trying to get downtown businesses to thrive, but this plan takes away the access to the downtown. This is not a good idea, unless the downtown is surrounded with traffic friendly roads and adequate parking. We have enough congestion without creating more. Stop this now.

  • http://stopandmove.blogspot.com/ Jass

    The video would have been better had it spelt out the safety benefits to drivers, and explained why capacity doesnt decrease.


    2 lanes each way. Anyone making a left or right turn will stop in the through lane, thus lowering capacity to one lane anyway, and creating collisions.

    Here are some examples of types of collisions that are reduced:

    The article doesnt mention situations in which a car would stop in the left lane, to allow a pedestrian to cross, and a car in the right lane would NOT stop, assuming the other car is waiting to turn, and not for a pedestrian.

  • ZA

    With all due respect, a quick Google search shows your town has enormous opportunity because of its 3-sided waterfront and two other regional highways (91 & I-95) to divert pass-through vehicles away from your town. *Appropriate* lane diets could create the connections between your commercial districts along Atlanta, Ocean, Osceola, and Palm City Rd. for pedestrians and bicycles. You even have a bicycle shop already, near Ocean, but it’s isolated from the rest of your town by the “wall” of highways. Lane diets don’t generate more congestion; instead they limit your existing congestion while carving out roadspace for other uses. How you care to address this opportunity is your own affair, but it’s knocking on your door.

  • Ty

    What is going on in Stuart, Florida?! I'm looking at Google Streetview and all of your roads seem to be small two-way roads and roads that already are 2-lane plus a center turning lane. Am I missing something?!

  • http://profiles.google.com/andy.sfbike Andy Thornley

    Big hat tip to the San Francisco Municipal Transportation Agency for really going to town, so to speak, on road diets and roadway re-allocation, SF streets can definitely still use some slenderizing but we've shed miles of unsightly travel lanes . . .

  • Bob Davis

    "Road Diet" seems to me to be another one of those "jargon terms" like "traffic calming". "Reconfiguration is a more cumbersome term, but is more accurate. After all, a road is a paved (usually) surface; it does not consume food. And for anyone who's tried to lose weight, "diet" is often associated with deprivation and discomfort. Likewise, "Traffic Calming" is often more accurately called "Motor Vehicle Restricting." Both ideas have benefits, but to borrow a line from Howard Cosell, "Telling it like it is" lets everyone (including those who aren't bicyclists or transit enthusiasts) know what's happening. For a motorist in a hurry, finding his favorite route to the freeway has been "traffic calmed" will make him anything but "calm" ("What nitwit turned my road into a @#$!! obstacle course!?!"). I know, so many of us seem to be always in a rush, and we should plan ahead and slow down but that's not the way the modern world works.
    (off topic, but relevant at this time of year: I don't like the term "Daylight Saving Time" either. So-called DST saves not one microsecond of daylight. More accurate would be "Activity Rescheduling Time".)
    (and just in case anyone wonders, I am a fan of the late George Carlin)

  • Maxemom4

    good and helpful post thanks

  • http://twitter.com/mariotanev Mario Tanev
  • A1394929

    Agreed. It'd work really well for Downtown Broward too.

  • Anonymous

    Of course, many of us don't really give a crap about the social-engineering agenda of making the world better for pedestrians and bicyclists.

  • https://www.magazinemall.in/ProductList.aspx?CID=3 Automobile magazine

    What is the advantage of filling NITROGEN GAS in automobile tyres? Have any problem in long running?

  • Anonymous

    Basically, None.  Except that your wallet will be a little lighter and you valve stems will have green caps.  Please remember that unless you vacuumed all of the air out of the tire before filling (impossible to do with a tubeless tire) about the most nitrogen you will get in is about 40%.

  • http://www.facebook.com/rpvitiello Ryan Vitiello

    oxygen molecules are smaller, so they can more easily "seep" out of the rubber tyre. Nitrogen molecules don't seep thorough the rubber as easily, so you have to reset your tyre pressure less often.  At my job (a new car dealer) they fill all the cars on the lot as such, since the cars can sit for long periods of time before they are driven. 

  • http://www.facebook.com/rpvitiello Ryan Vitiello

    The only issue I have with "traffic calming" is when you don't have an alternative high speed route away from pedestrians (like a highway) to move vehicle traffic quickly. The last thing we need it to slow down traffic even more by miss, or over applying traffic calming. 

  • http://www.MesaVillage.com Jeff King

    Thanks for this well done video.  I've added it to our neighborhood planning website, http://www.MesaVillage.org, to support our push for a more sustainable community.

  • Hummer9

    this is absolute PROOF that people in government still smoke way too much good weed !

  • http://www.facebook.com/fxpeters Frank Peters

    One of my all-time favorite Streetfilms!

  • Rex Burkholder

    Great, clear explanation of a great idea. I shared it with our mayoral candidates in Portland, Oregon where we still are fighting to make our main streets safe for cyclists and pedestrians.

  • chekpeds

    This is awesome. So clear. Any man or woman who has lost 30 pounds will tell you : it works.. he or she gets more of everything that is good and lose more of what is bad..

  • topt

    Nitro gen is a very dry gas, has no moisture in it to expand when heated therefore your tires will not gain as much pressure when they heat up. Constant pressure is constant performance and safety.

  • Seattle


  • se7atcom

    good and helpful post thanks


  • Vivian Hurst

    Why can't there just be one lane in each direction and change the street parking from parallel parking to diagonal parking. This will allow for more street parking spaces and will also slow down the traffic speed.

  • Chris Bauman

    what is the program used to create those road diet displays? is that a website?

  • RGD

    Air is 70+% Nitrogen anyway, so it really doesn't matter that much.

  • RGD

    You may view it as social engineering. I view it as the reversal of social engineering: we have only built such wide roads since about the 1930's, and did not have any in significant amounts until the 1950's or the 1960's. Compared to the length of time we have had cities (7000+ yrs.), this hardly makes any significant amount of time.

  • RGD

    It is a design problem, but this only comes about when a road diet converts a two way road with an even number of total car lanes to a two way road with an odd number of car lanes (such as the common 4 lane to 3 lane conversion). I think your concern is valid, but I can't imagine it being any worse than having traffic speed tremendously all along the corridor. Perhaps there should be pedestrain refuges on each side of the left hand turn lane at crosswalks to mitigate this problem (because, even though "jaywalking" (a term I think is insulting) will likely increase with a road diet, it seems unlikely that most traffic will jaywalk even with the road diet).

  • Easy Way #6

    Imagine how quickly traffic would move if all lanes were eliminated! And the multiplier effect is humongous: Global warming? Solved. Obesity? Solved. Fitness crisis? Solved. Trump impeached? That might take longer ; [