Safety, Traffic, and You: The Case for Road Diets

Much Ado About 1 Lane

As we here at the LADOT Bike Program experienced late last year, there can be quite a kerfuffle over removing even the slightest amount of roadway space for drivers.  The controversy over the Wilbur Avenue road diet last year caused quite a bit of hand-wringing and gnashing of teeth.  In the LA Times, on Streetsblog (a few times), the Beckford Ave School PTA, the LAist, LACBC, City Watch, Biking in LA; coverage on the project was as broad in scope as it was diverse in opinion.

Bike Lane on San Pedro looking South at 115th

A successful road diet on San Pedro in South LA

What it all came down to was a change of 4 lanes of traffic on Wilbur Avenue to 3 lanes  – with bike lanes added to both sides of the street.  At the time, some painted the road diet as a real estate grab for bicyclists at the expense of drivers.  There were claims that the road diet would make traffic unlivable; that it would force cars onto other streets and make the surrounding neighborhoods less safe.

Fighting for Road Diets

While some of these claims might be chalked up to the dreaded Fear of Change, it would not be productive to treat them as such.  Instead, it demonstrates a need for those who support traffic calming and livable streets to communicate their vision more effectively.  When it comes down to it, both those who support and those who oppose road diets want good neighborhoods, they want less pollution, and they want safe streets.  As roadways with excess capacity have been the modus operandi of traffic engineering for the last 50 years, it falls on the shoulders of those who support road diets to make their case.  Many have already done so.

This is our case, made in favor of Road Diets.

Road Diet – Defined

A “road diet” is typically comprised of converting a 2-way, 4 lane street into a 3 lane street with bike lanes on either side.  One travel lane goes in each direction while the center lane is marked as a “two-way left turn lane” (TWLTL).  Road diets are often planned to coincide with a scheduled repaving of a street, and thus come at little cost to the City because the road being repaved would need to be re-striped anyhow.

Wilbur Avenue, Revisited

We should point out that, in the case of Wilbur Avenue, the road diet preceded the bike lanes.  Though bike lanes on Wilbur Avenue are on the 1996 bike plan, the idea of a road diet on Wilbur Avenue sprung from non-bicycle factors.  LADOT traffic engineers, after reviewing both the average speeds on the street and the history of crashes along the road, determined that a road diet would make the street far safer for all users without significantly impacting congestion.  The resulting road diet ended up providing benefits to all users.

Myths Dispelled

There are a lot of myths surrounding road diets, and they are quite pesky to dispel. That’s because, quite honestly, they appear common-sense on their face.  Take away a lane of travel?  You’re creating more traffic, more pollution, and making the road less safe.  Add a bike lane too?  You’re putting the needs of bicyclists over those of drivers.  Roadways, it seems, are a zero-sum game: If you give something to one group, you must take from another.

But if we delve into the issue a bit, it’s shown that road diets can actually be beneficial to drivers, beneficial to bicyclists, beneficial to pedestrians, and beneficial to communities. Imagine that!

Road Diets Can Improve Traffic

Seems a little strange, doesn’t it?  When a 4 lane road is below a certain volume of traffic (usually 18,000-20,000 Average Daily Trips – ADT), implementing a road diet can actually make traffic flow more smoothly.  Especially on streets that have cars making frequent left turns (like, say, a residential street with plenty of driveways), creating a two-way left turn lane creates a space for turning vehicles that won’t impact moving traffic.  Think about it another way: when a left-turning car comes to a stop in 2 lanes of travel, that direction immediately becomes 1 lane of travel.  Even worse, cars merging right will snarl traffic even further.  A road diet gives that driver a place to turn that won’t impact the free flow of traffic.

On top of that, every person who is encouraged by the bike lanes installed to ride their bike (instead of drive) on local trips around their community means one less car on the road to create congestion.

Road Diets Improve Safety – For Everyone

Road Diets improve roadway safety for all users, but let’s go through each to really drive the point home.

Driver Safety

Road Diets help improve car safety in many ways.  A study conducted by the Highway Safety Information System for the Federal Highway Administration found that road diets reduced crash frequency by 29% per mile from reconfiguration alone.   The slimmed-down roads encourage slower driving speeds, which automatically make driving safer.  They also help to prevent three specific types of car-on-car accidents.

  • Rear-End Accidents – The two-way left turn lane moves turning cars out of traffic.  In a 4 lane, high-speed road, it can be very easy to hit a car from behind when they put on their left-turn blinker and slam on their brakes.  With a road diet, the turning car merges into its own lane and out of the lane with through traffic.
  • Side-swipe Accidents – The other bad outcome of a left-turning car without its own lane, a side-swipe happens when a driver swerves into the right lane to avoid someone stopped in the left lane only to hit a car traveling in the right lane.  With a road diet, both cars are already in the right lane.
  • Blind-side Left Turn – A blind-side left turn is when two cars, going in either direction, both want to turn left.  The stopped car in the left lane can block the view of a car in the right lane farther back.  The car in the other direction makes the left turn only to be struck on the side by the oncoming car in the right lane.  With a road diet, both left-turning cars are in the same lane, facing each other, which removes obstructed views of oncoming traffic.

Bicycle Safety

By adding bike lanes to a street with a road diet, bicycling becomes safer in two ways.  (1) Creating a space on the roadway dedicated to bicyclists, drivers will be more cognizant of bicyclists on the roadway.  (2) Creating a bike lane also has the effect of encouraging more people to get their bikes on the road.  There is safety in numbers, and the more experience drivers have sharing the road with bicyclists, the safer both bicyclists and drivers will be.

Pedestrian Safety

Pedestrians on the sidewalk will also benefit greatly from a road diet.  Not only will cars be traveling at slower speeds on the road, the addition of a bike lane creates 5 more feet of space between pedestrians and moving cars.  Drivers traveling at fast speeds are often subject to “tunnel vision”, meaning that they only register those things straight ahead and in the distance.  By bringing speeds down to a safer level, the field of vision a driver recognizes expands dramatically, making it more likely they will notice a pedestrian crossing the street before it is too late.

Road diets also make streets more enjoyable for the people who live along them, lowering street noise, discouraging speeding, and making their yards safer.  Many streets receiving road diets are residential.  By improving safety and lowering speed and noise from traffic, road diets can help to make these streets livable and enjoyable.  Yards become safer to play in and property values go up as noise and speeding go down.

Road Diets Bring Streets to Their Appropriate Scale

When complaints surface that a road diet will create “gridlock” on a street, this often refers to rush-hour periods when streets experience heavy traffic.  But what about the other 22 hours of the day when there are barely any cars on the road?  An empty 4 lane roadway is practically an invitation for a driver to speed, creating dangerous conditions for the people who live along the road in question.  A City shouldn’t have to sacrifice quality of life and piece of mind for 22 hours a day just to accommodate the other 2 hours when a street may need extra capacity.  This unused roadway requires maintenance and eats up land that could be put to other uses in a City where space is at a premium.

Road Diets Comply with State Law

The concept of road diets also satisfies AB 1358, the Complete Streets Act, which stipulates that transportation plans must comply with the needs of all users, be they drivers, bicyclists, pedestrians, or others.

What’s the Point of a Road, Anyhow?

No, really: what’s the point of a road?  Is it just to move cars?  What about pedestrians?  What about bicyclists?  What about the people who live along the street, do their needs count too?  Should a roadway being safe matter?  How safe is “safe”?

When the idea a road diet comes up, usually only the first question about the cars dominates the discourse.  But all of these other questions should figure into our train of thought when considering our roads.

0 replies
  1. Kevin
    Kevin says:

    The reasons for “road diets” (where one or more lanes are eliminated) seem obvious and make a lot of sense. The fact that certain council members never seem to comprehend this only makes me think that perhaps “council diets” (where one or more council members are eliminated) might make even more sense.

  2. Dennis Hindman
    Dennis Hindman says:

    Nice argument in support of road diets. I missed seeing posts like this in the last few weeks.

    Los Angeles will be attempting to impliment many more road changes to accomodate bicycles in the future. To hopefully learn from those that have been there before us, here’s a audio recording of a New York City Counsel Transportation Committee meeting where Transportation Commissioner Janet Sadik-Khan is grilled by counsel members about the 200+ miles of bicycle infrastructure that have been implemented in the last three years and it’s impact on the city.

    Here’s a video recording of a presentation that Mikael Colville-Andersen gave where is mentions that in the 1980’s Copenhagen put in cycle tracks for bicyclists on less busy parallel streets compared to the main arterials to get bicyclists out of harms way and they were a utter failure because they were not as direct a route from a-b.

    Hopefully Los Angeles will get more bold and aggressive in putting some sort of barrier between cyclists and motorists on the arterial streets when the new bike plan starts as New York City has done in the past three years. Simply painting bike lanes will not convince many people that it is now safe to ride a bike on these streets. Paint on a street as a barrier runs counter to human instinct of self preservation from predators and cars traveling at 35+ miles an hour triggers that reaction in most people that I have talked to.

    Recently I road my bike from the Orange Line BRT to REI on Devonshire Blvd and I would have to guestimate that about 2/3 of the people riding bikes were on the sidewalks and forget the sharrows as that requires not only riding on the street but in the middle of the horsepower lane. Having sharrows in the middle of a busy arterial street is something akin to taking part in the running of the bulls in Pamplona Spain and Reseda Blvd does nothing but support that conclusion. If only 1-2% of experienced cyclists use it, then does it have any hope of substantially increasing the volume of cyclists?

  3. bikerdude
    bikerdude says:

    The city council and the mayor need to understand that more bicycle friendly streets in LA; would give confidence to parents, bicycle commuters and children to ride their bikes or walk to school, and other sites.

    The Mayor says he is “green” and the road diets will let us enjoy a better quality of life, allow the community to be active, and healthy and give us diverse transportation choices.

    The bottom line is to have a better natural and social environment in the City of Los Angeles.

    Road diets would make the streets of Los Angeles a more welcoming experience for the children, and adults who ride their bikes or walk.

  4. alexis
    alexis says:

    Great post Chris! Thanks for breaking the benefits of road
    diets down for all to understand – Rach’s flyer idea is great –
    that will be helpful as all of us work together to build support
    and demand for road diets in neighborhoods all around the

  5. Josef Bray-Ali
    Josef Bray-Ali says:


    If this stuff is well understood in engineering circles, then why was traffic calming on North Figueroa Street rejected by the LADOT?

    The consultants subcontracted to analyze streets in LA for bike facilities saw that North Figueroa Street, which has room for 30,000 to 50,000 ADT, wasn’t coming close to half of that along the majority of its length.

    I have lived, and now own a business, on this road and I have seen a lot of car crashes (most of which go unreported).

    The neighborhood businesses are hurt, as is the social atmosphere in the community, by a lack of safe and peaceful walking and bicycling space. Yet the LADOT made sure that traffic calming was excluded from the Bike Plan.


    • ladotbikeblog
      ladotbikeblog says:

      @Josef – I’m not intimately familiar with the details on N. Figueroa, but I’d be happy to look into it. There can be secondary concerns after ADT measurements which can get in the way of road diets. I’ll see what I can find.

    • ladotbikeblog
      ladotbikeblog says:

      @Josef – after some digging I found that, when those studies were first conducted, concerns about peak-hour LOS on certain areas of the street precluded traffic calming suggestions despite a relatively low ADT for large sections of N. Figueroa. Sucks.

      The good news, however, is that things have changed a bit over here since those first studies were conducted (hard to believe though it may be), and the department is more receptive towards traffic calming than we once were. Things are still in flux for the specifics of the bike plan, and you should get your community to reach out to both planning and your Council Member to include more traffic calming measures to accompany bike lanes on N. Figueroa in the new Bike Plan. Once it’s in the plan, you’ll have much more leverage in getting LADOT to carry it out.

      • Jessi
        Jessi says:

        Just call it a “complete street”. The term “diet” makes it
        sound like we’re sacrificing something we value for something
        superficial, when the reality is that we’re reforming a space
        monopolized by one type of user so that it serves everyone’s needs.
        We have a complete streets initiative that recently passed in
        Minnesota, and nobody talks about “road diets”. Great blog, Chris
        and Oliver! Thanks for the regular updates on biking in

  6. bikerdude
    bikerdude says:

    I suggest you talk to your council person, mayor office, neighborhood council and get some political clout behind the road diet project.

  7. Bob Davis
    Bob Davis says:

    “Road Diet” does have the connotation of deprivation and restriction. “Complete Street” sounds more positive and even rhymes.

  8. healthy diets guide
    healthy diets guide says:

    Howdy! I could have sworn I’ve visited this blog before but after browsing through a few of the articles I realized it’s new to me. Anyways, I’m definitely happy I found it and I’ll be book-marking it and checking back frequently!


Trackbacks & Pingbacks

  1. […] A total of 51.9 miles of road diets have reshaped the landscape of streets in Los Angeles since the City began implementing them in 1999. However, many new road diet projects were implemented after the adoption of the 2010 Bicycle Plan. It is important to note that road diets are not just meant to serve bicyclists. Discussing the safety impacts of road diets clarifies that road diets equalize the playing field and create safer streets for people walking, bicycling, taking…. […]

  2. […] Friday, LADOT crews began the work of extending the bicycle lanes and road diet on West 7th Street into Downtown LA’s Financial District and Historic Core. Since this is […]

  3. […] road diets are officially acknowledged by the FHWA as a proven means to improve safety and the logistics of why road diets succeed in doing this  have previously been laid out on this […]

  4. […] level, road diets are officially acknowledged by the FHWA as a proven means to improve safety and the logistics of why road diets succeed in doing this  have previously been laid out on this […]

  5. […] to me that the blog was a great place to share perspectives and opinions. Finally, on a post about road diets, I volunteered to help out and the rest is […]

  6. […] Los Angeles Department of Transportation Discussion […]

  7. […] Abbass Vajar, also in attendance) explained many of the benefits of the project, including safety (which we’ve discussed before), as well as some of the technical details. The original design had 5′ bike lanes, but […]

  8. […] safety for all road users whether they be on bicycle, foot, or in a car. You can also check out LADOT’s blog post about the benefits of road […]

  9. […] Bike Blog has given a lot of thought to road diets and one lane reductions in a previous post here. A good example of how these work is now available on 7th St., between Catalina and Valencia (soon […]

  10. […] possible benefit of bike lanes on 7th Street is that, by introducing the two-way left turn lanes ubiquitous to a road diet, the project may be able to improve the design of intersections and explore additional parking […]

  11. […] Both Streetsblog and the LACBC alerted their readers this week to the Neighborhood Council meeting, where the case was made for a road diet to extend existing bike lanes along Main Street from the Santa Monica City Limit to Windward Circle (a project listed as “pending work orders” on the LADOT Bike Blog Bike Lanes Projects Page).  The concept of a road diet, which would create enough room for bike lanes on Main Street, was covered earlier this month by LADOT Bike Blog in our piece Safety, Traffic, and You: The Case for Road Diets. […]

  12. […] makes the case for road diets using good graphics to help explain that the new design benefits people using ALL modes of […]

  13. […] public face of the agency — offers an in-depth look at upcoming bike lane projects and makes a solid argument for road diets. Streetsblog looks at the new and improved Ohio bike lane, a side-benefit of the massive 405 […]

  14. […] LADOT Bike Blog Writes a Defense of Road Diets […]

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