When Cities Force Developers to Widen Roads, Everyone Loses

At L.A.’s Vermont-Wilshire Towers, the city made the developer cede land and pay for 6,000 square feet of road widening. Photo: Google Maps

It’s a common practice for cities to make developers widen a street when they put up a new building. The thinking is that development creates car trips that must be accommodated with more asphalt.

But new research suggests these policies don’t help anyone. The main effect is to increase the cost of building, making housing less affordable.

“As traffic management exercises, many widenings appear unnecessary,” concludes UCLA researcher Michael Manville in a paper published in the Journal of Transport and Land Use [PDF].

Manville looked at how this policy is carried out in Los Angeles. In L.A., all multifamily housing projects (and some other types of construction) are assessed by city traffic engineers to determine whether the developer should widen nearby streets. This is like “blaming Disneyland for increased air travel, and forcing the theme park to expand runways whenever it adds attractions,” he argues.

Manville spoke to developers compelled by the city to pay for various road widenings. The costs varied. In one case, the street widening added an estimated $11,000 to the cost per unit of a multifamily housing development. In another case the figure was $50,000. In another, just $65 per unit. Where the costs of street widenings are substantial, the policy drives up costs for renters and buyers.

As for reducing congestion, the whole practice of street widenings to accommodate development appears to be “largely symbolic,” Manville writes.

Manville examined a random sample of 278 street widenings paid for by L.A. developers between 2002 and 2012. He then compared vehicle counts on those streets to the volume of traffic a street of that width is supposed to handle. How many cars were actually on streets that had been widened to handle between 30,000 and 50,000 vehicles per day?

In most cases (52 percent), the answer was “fewer than 30,000 vehicles” per day. On smaller streets, Los Angeles planners were even worse at matching street width to traffic volumes. Nearly two-thirds of streets (63 percent) that had been widened to handle up to 10,000 vehicles per day in fact saw fewer than 5,000 vehicles per day.

Furthermore, in about 20 percent of cases, the city had no traffic counts at all on which to base the decision to widen.

Even if the road widenings had the predicted effect, they would still, of course, be a terrible policy for cities. Wider roads are more dangerous roads, leading to more injuries and fatalities. And while more asphalt might make it more convenient for more people to drive at peak hours, in the end that would just increase the number of cars on the road. Raising the cost of driving is the only effective way to reduce traffic.

“The evidence suggests that mitigation laws have low social benefits and higher social costs; more is lost in housing than is gained in mobility,” Manville concludes.

36 thoughts on When Cities Force Developers to Widen Roads, Everyone Loses

  1. Don’t forget the Chuck Marohn argument here. Cities, including Los Angeles have huge backlogs in street maintenance. L.A.’s is estimated to be more than $2B. Why do we keep widening streets when we can’t afford to maintain the ones that we already have?

  2. And let’s not forget that these widenings only apply to the portion of the street directly adjacent to the property. That means many properties all in a row would need to be rebuilt before there would even be a conceivable effect on the vehicle traffic (decades; maybe longer). This means that until then, it’s just wasted roadway width that serves no purpose aside from encouraging illegal speeding and increasing difficulty in pedestrians crossing streets.

    Now, as another posted noted, if this increase width could be limited to BRT or bikeway use, then maybe that’s something. I could even envision changing the requirement from widening the roadway to widening the sidewalk and adding a healthy amount of additional street trees. We could certainly use the shade canopy.

  3. Additional width of a street does not have to be used for motor vehicles. It could be exclusively for transit, pedestrians or travel by bicycle.

    The city of Los Angeles has put on-street bike lanes and off-street bike paths in areas that have excess road capacity or off-street room for paths. Those areas of the city that have narrower arterial streets per population tend to have few, if any, bike lanes or paths.

    Realistically there is not going to be a connected network of bike lanes and bike paths in areas of Los Angeles that have few motor vehicles lanes per population without additional space to install them in. Swapping out a mile of motor vehicle lane that carries thousands of people per day for bike lanes that initially would carry no more than a few hundred is a recipe for failure as motor vehicles are squeezed into a smaller area on streets that are already traffic congested.

    The predominant reason that subways were built in populated cities from the late 1800’s onward was due to not having room or excess street capacity on the surface to install a fast moving train there. That existing surface transportation was not only cars and trucks, but also pedestrians and horses in the earlier years of subway construction. Digging a subway tunnel creates more room to move people in high population density areas of a city in much the same way as widening a street does.

    Choosing not to widen a street a city could be guaranteeing that motor vehicle travel remains the dominant form of transportation as every other form of transportation is squeezed by the dominance of motor vehicles.

  4. Most of these widenings happen because agencies have identified target widths for ultimate build out of the roads and streets. Requiring developers to make the ultimate half-width improvement is a common mitigation measure conditioned on projects and is usually done due to the fact that they’re building in a certain place and as noted here, those improvements may not even be necessary from a traffic operations standpoint.

    However, let’s not throw the baby out with the bathwater. This can be a great opportunity to build links for stronger transit and bike networks because the developer is usually conditioned to build the frontage to whatever the standard is for where the project is located. Most developers don’t really care too much what those standards are since they’re passing the costs on to the customers anyway, but they don’t usually get to decide what exactly is built. That means that advocates need to focus more on getting agencies to not just adopt (often nebulous) “complete streets” policies that “consider” transit, biking, and even walking, but actually adopt standard sections that reflect that commitment (e.g. pictured).

  5. Or don’t widen the street and do a full legth bus lane using the existing number of lanes.

  6. This expectation that cities have to build big roads before they can start looking at alternative transportation is senseless. Many places have adopted or are considering complete streets policies. If those policies truly prioritize other modes like they purport to, then the other modes should be expected even in the absence of cars. Additionally, it’s deceptive to use Dutch figures that measure biking as a share of all trips to American figures that only measure biking as a share of commute trips to claim that we can’t do anything for bikes at the expense of cars. That’s a false dichotomy, with reams of research, including Dutch, showing that the more quality bikeways there are, the more people are willing to bike. As it is, most Dutch biking is also not commuting, so their figure would also be way lower, probably in the Boulder range, if only commute trips were measured.

  7. Its easier to install bus only lanes or bike lanes on streets that are wider. There are not too many bike lanes installed on residential streets due to the narrower width.

    Starting from a very low mode share for bicycling makes it difficult to obtain space that is already used by the dominant form of transportation. Taking out motor vehicle lanes that are used by 25-50% of the traffic on a street and replacing it with bike lanes for 1% of the traffic is a swap that cannot continue for very long without roads that have excess capacity or unused space. The push back from motorists would be too great if a city continues to create large traffic jams on streets during peak hours by taking away motor vehicle lanes to install bike lanes.

    There are only about 30 miles left out of the 3,000 miles of arterial streets in the city of Los Angeles where bike lanes could be installed without creating D or F levels of traffic congestion. A F level of traffic congestion is when there is more motor vehicles than the street can handle.

    The arterial streets in the mid section of Los Angeles have motor vehicle lanes that have been narrowed to 9.5 feet to squeeze in another lane for motor vehicles. During peak hours parking has been prohibited for decades on some of those arterial streets in order to create temporary travel lanes. There simply is no room to install bike lanes without creating massive traffic jams.

    Its easy for a city to proclaim that they are now pro multi-modal and draw some bike lanes on a plan. Actually creating a connected network of minimum width bike lanes is something that could take decades in most U.S. cities. Using the Dutch standard bikeway widths as a minimum would compound the difficulty of that.

  8. Why not take the same line of thought with bike infrastructure as we had with subways in the late 1800s? I’ll concede your point that often there just is no room to put bike infrastructure at surface level. Fine. Build it above or below grade instead. It’s far less expensive to grade separate bike infrastructure than to do so for trains. The resulting structures (if they’re above grade) are far less intrusive. And the average speed of bike travel is greatly increased once you avoid the need to slow or stop at red lights. It seems like a win all around. You’re essentially creating new space out of thin air, same as was done when we built subway tunnels.

  9. Its a rare situation where grade separating bicycling is done in a U.S city. Making long subway like tunnels is out of the question for travel by bicycle or walking due to prohibitive cost and social danger. Creating grade separation by putting a bike path next to a river or former railway is commonly done. Three city council members in the city of Los Angeles have recently given enough money out their own budgets to do a engineering design for a mixed use path along the San Fernando Valley portion of the LA river. That would create a meandering path which is uninterrupted by cross traffic from the west side of the valley to the east side.

    However, for the mid section of Los Angeles there is no unused railway space or river available. This limits bikeways to existing roadways. There is no way to get separation on arterials in that area due to traffic congestion, which limits low-stress routes for bicycling to mainly mixed use on residential streets at first. If bicycling becomes significant enough in that area, then, perhaps, in the future some space could be carved out for a bikeway on arterial streets. It would take a long time for that to happen.

  10. “Taking out motor vehicle lanes that are used by 25-50% of the traffic on a street and replacing it with bike lanes for 1% of the traffic…”

    It looks like you’re confusing mode share of a city with mode share of a particular street. A new bike lane that becomes popular can easily carry 10-50% of the street’s users, while taking up a fraction of the space it would take to carry that many people in cars.

    “There are only about 30 miles left out of the 3,000 miles of arterial streets in the city of Los Angeles where bike lanes could be installed without creating D or F levels of traffic congestion.”

    This is quickly becoming irrelevant – California is moving from using Level of Service to Vehicle Miles Traveled as the major metric on which to judge if a street must be widened. Plenty of D and F level streets remain vibrant commercial or residential corridors with street life and vital importance to their city’s economy. For obvious reasons, VMT is unlikely to increase when a bike lane is added to a street, hence “mitigation” (widening) would not be necessary.

    The LOS concept is an outdated and harmful one, and it’s about time we get rid of this 60’s relic.

  11. I can count on one hand where bicycling might be at least 10% of the users on a street in the city of Los Angeles. Swapping out 1-2 motor vehicle through lanes for bike lanes on extremely busy arterial streets in the city of Los Angeles has a very limited potential. There is less than 60 miles out of 3,000 miles of arterial streets in LA where there has been a road diet, some of which have gotten bike lanes.

    Traffic congestion has not become irrelevant. Motorists are acutely aware of the result from taking road space away from them. They will make their voices heard very loudly if their trip times are negatively effected by giving space to a few bicyclists.

  12. > Cyclists also totally avoid having to deal with motor
    > vehicles or pedestrians.
    Non-vehicular infrastructure must and will remain multi-use. This means pedestrians, skate boards, roller skates, kick scooters and bicyclists. Deal with it!

    Cyclist to driver: “Share the road”
    Cyclist to pedestrian: “Get off my bike-way”

  13. I’m not discussing mixed use paths in parks. I’m talking about building bike viaducts above streets where surface level bike infrastructure won’t fit, or would be grossly suboptimal. Generally you’re not going to see large numbers of roller skates, scooters, or skateboards outside of parks, so any discussion of them in the context of bike infrastructure mostly designed for utility cycling is moot. As for pedestrians, please tell me why on Earth you would allow pedestrians on such a thing when they already have sidewalks? And why would they even want to walk there when it would entail a climb, plus constantly dodging speeding bikes? “Shared” infrastructure was in vogue in the 1950s. Time has proven it doesn’t work unless it has very few users. Also, we’re perfectly willing to build very expensive motor highways where cyclists and pedestrians aren’t allowed? Shouldn’t cyclists get something similar?

  14. What’s wrong with going above the street when you have no railway space or river? It costs money, but far less than a tunnel. You could argue there’s not enough demand for it, but the hard fact is if places like LA keep the status quo there will never be all that many cyclists. You have to build the infrastructure first. Once people know they have a safe, fast, comprehensive way to get around they’ll use it. You don’t even need viaducts over every street, just over main arterials where cyclists don’t feel safe riding. Residential streets could provide last mile connectivity.

  15. People use all of those modes to commute – it has nothing to do with proximity to parks. Those people are exposed to the same dangers and inconveniences at intersections as bicyclists, albeit to different degrees. If you want to go fast – mix with the cars. If you want to be safe, mix with other modes and play nice.

  16. The problem is you *don’t* go fast mixing with cars because of stop lights, double-parked vehicles, buses, etc. I don’t know what makes you think riding with cars is fast. It isn’t.

    I probably wouldn’t have an issue allowing skateboards, scooters, or roller skates on bike viaducts given that they move much faster than pedestrians, plus would probably be relatively few in number. I’m just not seeing why you would need to allow pedestrians. They already have their own protected infrastructure in the form of sidewalks. Now if you want to build a separate pedestrian viaduct, accessed by stairs instead of ramps (so bikes can’t accidentally use it), I’m fine with that. It might even make the idea more palatable since everyone would get something out of it.

    Note that we have some heavily used shared paths in NYC and they’re a disaster for everyone. People don’t place nice with each other. Pedestrians step out in front of bikes without looking. Bikes speed through crowds of pedestrians. It’s not pleasant or optimal for anyone, which is why it’s no longer recommended practice.

  17. > They already have their own protected infrastructure
    > in the form of sidewalks.
    So do bicycles, in the form of lanes, marked or protected. But you are talking about degrees of improvement, both for reasons of convenience and safety. Cars plow in to the sidewalks or mow down pedestrians in cross-walks. Why are they less deserving of your proposed benefits as compared to bicyclists?

    If a separate and equivalent infrastructure is desirable for bicyclists, it is just as desirable for pedestrians. If people don’t want to share the space, they will have to share the costs twice over by building 2 similar paths.

  18. An elevated cycle track above arterial streets would not get enough political will in terms of money and the visual clutter. There is not enough money to maintain existing roads and sidewalks, which means this idea would be not feasible.

    That idea has been proposed for the city of London. It would isolate cyclists from destinations along arterial streets:


    Making the LA river more attractive looking and accessible has enough political will to seek money for a mixed use path through grants or perhaps if the upcoming county wide half-cent sales tax passes at the ballot box.

    The LA County Metro has gotten money to convert an old railroad right-of-way along Slauson Ave to a mixed use path. Currently its just blight and its not considered very useful as a light-rail line.

  19. I fully agree the ideal here would be separate and equivalent infrastructure. It’s not going to cost twice as much as a shared path, either. You can have one set of supports for everything. Instead of building a 15′ wide viaduct for a shared bike/ped path you instead build a 20′ wide viaduct—12′ for bikes, 8′ for pedestrians. Separate the bike and ped portions with a fence. You’ll need separate access for each portion but that won’t add significantly to the cost compared to a shared path. A shared path would need somewhat frequent access (every block?) for pedestrians anyway, so you put that on the pedestrian path. The bike path needs less frequent access (perhaps 3 or 4 exits per mile).

    Shared paths are often built when there’s no room along a right-of-way for separate, dedicated infrastructure. If you’re going above the right-of-way those constraints no longer exist.

  20. If LA has money for highways it has money for this. It’s just a matter of priorities. The idea London proposed is ridiculous precisely because it mostly doesn’t go where cyclists want to go. It’s also grossly oversized. What I’m thinking of is basically like a slightly wider pedestrian overpass. Not very intrusive, and compared to motor highways not very costly. If we refuse to optimize things at street level for bikes then we need to look elsewhere. The Dutch got rid of a lot of motor traffic and traffic lights in the process. They’re even grade separating bikes at some major junctions.

    If you’re going to wait for bicycling to become significant before carving out more space for it you’ll be waiting forever. Existing low-stress routes on residential streets don’t constitute a comprehensive bike network.

  21. Highways are not the domain of the city of Los Angeles government, that’s taken care of by the state. As I stated the city of LA does not have enough money to maintain their roads and sidewalks. There is not enough money in the city of LA’s transportation budget to build much of anything, let alone something specifically for bicycling. When there is a path built in LA, such as along the LA river or railroad right-of-way, the funds come from grants.

    Most of the street network in the city of Los Angeles is a grid design. A low-stress network for bicycling can be created using mainly residential streets as this report demonstrates using the city of San Jose for the study:


    Ronald Tamse, a traffic engineer for the city of Utrecht, made a presentation at Portland State University in 2011 about bicycling after touring Portland and Eugene. He was asked by a audience member what would he do to improve the rate of bicycling over the next ten years in Portland. His answer essentially was to do the easiest things first, which would be to work on residential streets and avoid the arterial streets due to confrontations. As more people bicycle, then work towards doing more difficult projects. This question and answer starts at 52:50 in this video:


    Creating more bicycling infrastructure in the 70 largest U.S. cities consists mainly of a lot of small steps. Trying to skip that and go right to the more major projects would usually involve a lot of nothing as very little progress would be made in accomplishing anything. Your looking at the 3,000 miles of arterial streets in LA as the only streets available to to make a network for bicycling, when in fact there are 7,500 miles of streets in Los Angeles.

  22. I can think of a number of places here in the San Gabriel Valley where new construction along a street required the developer to build a sidewalk and curb far enough from the center line to allow paved parking spaces, while adjacent lots extended further out and had no curb or sidewalk.

  23. Of course it’s easier to install bike/bus lanes on wider streets, they have more space to work with. But again, a wide street is not a prerequisite for installing them and if indeed, the issue is one of space, then it’s probably appropriate to remove the least efficient mode of travel from the corridor: private automobiles. That’s especially true for residential streets where there’s little reason for anyone who doesn’t live there to be able to drive through in the first place.

    Additionally, trying to blame congestion on bikes is spurious. There are already traffic jams on the streets of many cities, including LA, during the peak hours. This continues to occur even on roads that feature no bike infrastructure or even bicyclists at all such as I-405, I-10, I-5, I-110, etc. It makes no sense to keep blaming bikes, a mode of transportation that is at least six times more space efficient than cars, for problems caused by too many cars.

    Furthermore, even assuming that some projects do cause impacts, I could care less if cars have to wait more than 30 seconds to make it through a light and the state agrees, having already ditched the car-centric LOS standards. If the LOS argument is to be made, then the LOS values need to be tabulated for ALL users, not just the cars.

  24. Yes, we have a scourge of those type of situations here in the Inland Empire too. One parcel is ultimate width, the next lacks even basic curb & gutter improvements and the two extremes jump back and forth for blocks at a time.

  25. “bikes in tunnels” what are you 70 years old? this idea is always thrown around by old farts at public meetings who cant grasp that bikes and walking are a matter of convenience. you ride a bike 1 or 2 blocks sometimes just to get to the coffee shop. a bike tunnel on a commercial street is not only expensive to build enough ingress and egress points it is ludicrous considering bikes are meant to be convenient quick trip devices.

  26. The point isn’t to put bikes in a tunnel (or on a viaduct) just for the sake of doing so. Rather, it’s for the same reason we put trains above or below streets—to speed up travel. So long as we refuse to remove nonessential motor vehicles from city streets getting around by bike will at best be slow and tedious. It’ll often be dangerous besides. The tunnels or viaducts aren’t for someone going 1 or 2 blocks to a coffee shop (honestly it’s ridiculous to take a bike instead of walking in that instance). It’s for the people who might be going 2, 3, 5 even 10 or more miles.

    The general idea here is that I feel with the right infrastructure human-powered transportation can replace a lot of mechanized transportation. Bikes running non-stop in cities can be as faster or faster then subways door-to-door. If you start using velomobiles you can get average speeds of 25 mph or better. That starts to rival commuter rail. For this to happen, you need a combination of street level, “last mile” infrastructure (that also works for the person going a few blocks to the coffee shop), and non-stop, grade-separated infrastructure where people can do most of a longer trip. Note that even on a short trip the time savings can be significant. A 3 mile trip done at an average speed of 15 mph on grades-separated infrastructure takes 12 minutes. The same trip done at typical city streets with stop lights and congestion easily takes 30 minutes. You save 18 minutes each way, 36 for the round trip. It’s also safer, less stressful, less energy intensive.

    Another point is cities are getter ever denser. We’ve going to eventually have to start grade separating modes anyway just to avoid having everything grind to a halt. Just because grade-separated motorways through cities were an awful idea doesn’t mean we should dismiss any form of grade separation. We would probably opt for viaducts instead of tunnels in most instances simply because tunnels generally cost more. However, there may be some instances where we might opt for tunnels for aesthetic or other reasons.

    The “old farts” are the ones who want bikes in tunnels just to get them out of their way when they’re driving. They’re not envisioning that human-powered transportation has the potential to replace most driving.

  27. Barrington Ave in West Los Angeles is a good example of this phenomenon. It widens and narrows sometimes multiple times per block with no substantial benefit now or in the foreseeable future. What it does encourage, however, is drivers to illegally cut around stopped or slower traffic to try to “jump the line” of waiting cars.

  28. For obvious reasons, VMT is unlikely to increase when a bike lane is added to a street, hence “mitigation” (widening) would not be necessary.

    To take it a step further, adding bike lanes can actually be a mitigation measure now and any basically any project that would install them at the expense of general purpose lanes would basically be considered to have no impact at all from a CEQA standpoint. Now, a lot of agencies do still have LOS on their municipal codes, but that’s a separate measure and it still doesn’t preclude them from pursuing other solutions, including bikeways, to achieve the LOS standards.

  29. What you can count on your hands is pretty irrelevant at this point. Numerous studies have shown that better bike facilities attract more riders. Even if those bike facilities come at the expense of general travel lanes, bicycles can easily move six times as many people as the average car does through a space. So in other words, the removal of a general travel lane (or two) to provide space to build high-quality bike facilities can actually provide an increase in capacity of 500% over the lane that is removed.

  30. It doesn’t have to be a long wait. The City (or County) should include standards for transitioning the facilities as well as include budgeting for filling the gaps.

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