A Great Big Freeway — Thanks to Induced Demand

Traffic through the Sepulveda Pass is worse, thanks to a widening project. Photo:
Traffic through the Sepulveda Pass is worse, thanks to a widening project. Photo: biofriendly.

Los Angeles is getting what it paid for when it widened 10 miles of its most infamous freeways — another lane of traffic.

The extra lane of the I-405 between the 10 and the 101 freeways that opened in May, 2014, to supposedly alleviate congestion actually ended up adding a minute of travel time for drivers of the 10-mile stretch — and new data shows congestion is even worse.

The $1.6-billion infrastructure investment, known as the I-405 Sepulveda Pass Improvement Project, still resembles the parking lot at a Guns & Roses concert. Average commuting times through the Sepulveda Pass in both directions have gotten even longer in the last four years, according to data analyzed by the traffic analysis film INRIX from 2015 to 2019.

The most frustrating delays occurred during the afternoon rush when SoCal drivers heading north between 3 and 4 pm crawled along the I-405 at 19 miles per hour this year, instead of the jaunty 28 miles per hour they drove in 2015. That’s led to a 50-percent increase in travel time, from 23 minutes through the Sepulveda Pass in 2015 to 34 minutes this year.

The 405 isn’t the only SoCal freeway experiencing grinding delays. Rush hour speeds have slowed on 31 of 52 LA-area highways in the past four years, according to USC’s outlet Crosstown.

The reasons for the slowdowns are simple: The number of drivers on the road in Southern California has increased as 2.3 million more people have moved or grown up in the region and bought 2.1 million new vehicles over the past 15 years, putting more people on freeways and local roads. And widened highways encourage more drivers live further away from city centers, making people more dependent on driving. It’s a phenomenon known as the fundamental law of highway congestion, or induced demand.

For instance, since there’s no cost to getting onto the 405, if you add another lane to the 405, drivers who were taking an alternate route or leaving an hour earlier or later than normal, will instead drive on the highway during rush hour since that’s when they prefer to leave.

“At any given time the latent demand to be on a busy road is very high, so if you make it easier to travel on that road, all you’re going to do is attract some of the people who would be on the road but for the congestion levels,” said UCLA Luskin School of Public Affairs urban planning professor Mike Manville. “So you have a road that is every bid as congested just wider.”

For most Californians, $1.6 billion is a lot of money and it could have gone toward other transit projects that could move people around more efficiently. A proposed rail line could move transit riders from the West Side to the Valley through the Sepulveda Pass in only 15 minutes. It could open as early as 2033.

But the best option for reducing congestion in many transit experts’ opinion is tolling — especially along the 405 between the 10 and the 101.

“The beauty of pricing the road is that you don’t choose the way people behaviorally respond. That gives them an incentive not to do what is causing the problem,” Manville added. “When you do price the road, people switch to transit. We should let people figure out what’s best for them.”

16 thoughts on A Great Big Freeway — Thanks to Induced Demand

  1. Okay, so a question: How many passengers riding heavy-rail passenger trains traversing the Sepulveda Pass during rush-hour (the time when demand reaches its peak) would there need to be so as to reduce congestion on the I-405 for those 10 miles to the point where road traffic at those times would be free-flowing? Has anyone done a study on this that you know of?

  2. Okay, so why is this a major question? Why does transit ridership have to be framed in terms of “making space for you/others to drive?” That is why transit is not working in LA, because everyone thinks everyone else is going to ride transit so their own car trip is unimpeded and everyone else is “out of my way.”

    Public transit is about providing a reliable cost/time competitive travel option, since car travel is wildly variable depending on conditions. Transportation is about moving as many people as possible in different ways along a corridor, including trains and cars. Roadways will always be filled up to capacity as long as they are not priced as such. Where capacity exists and is cheap, it will be utilized. “Free-Flow” means the roadway is lightly used, which isn’t a good use of public resources, nobody wants to build a road that so few cars use that everyone can go 70 mph during the peak demand, that’s a waste of tax money. No single city in the world is both successful and rich without traffic congestion on both roads, sidewalks, and trains. You’ll find empty free-flow roads when people don’t have places to work or money to travel, like Detroit or Dayton.

  3. Tell this to the transportation brains in Marin County, CA. They’ve added a third lane to the Richmond Bridge east bound (actually just commandeered the breakdown lane) because SF commuters going home to the East Bay were backing up traffic on 101 N in the evening commute hours. The backup starts in a one lane section of Sir Francis Drake Blvd. access road and that hasn’t changed. Meanwhile the aging bridge is raining concrete down on drivers and being closed for hours due to lack of maintenance. There are no bridge Tolls for the Golden Gate and Richmond on this homeward commute, only on the inbound commute, so it’s basically free, except of traffic congestion.

  4. $1.6 billion would have paid for 1,000 miles of protected bike lanes ($1.5M each mile).

    But, you know, we don’t have money for that….

  5. Correlation is not causation.

    How do we know it isn’t just more people driving more cars? Isn’t that why Metro believes bus ridership is down, more people choosing to drive thanks to an improved economy?

    I’m not saying free-ways are a good thing but the premise of this article is that 1.6 billion was a big fat waste when the whole idea of “induced demand” relies on all drivers being morons who can’t time their commute (if they have other external constraints then it isn’t “induced” by another lane of traffic).

  6. I mean really?
    Did they not learn from Texas..
    More lanes mean more traffic not less.
    As the moment you add another land people who had previously take a slower route will take the express route as they think there will be more room, but they don’t realise and never do realise that they the only person who was driving on this slower road to notice a new lane on the fast road and the slower road people all move on to the fast road and then there is a new slow road because more lanes introduces the allowance of more traffic.
    This problem that happens all across America can be solved by making multiple 2 or 4 lane roads to the destination from different points, Cycle routes, or by funding public transport.

  7. Identify a problem exist; acknowledge it, takes too long to go, congestion, etc… increased probability of accidents. Formulate some solutions such as safe car pooling, improved safe public transportation, options, incentivize to use same… leave people an out.. cars with added safety features that help prevent accidents and crime…

  8. There is a correlation, building more and denser housing near employment centers… Not everyone will choose to live near their jobs but it should be an option for more people.

  9. Induced demand is a simplistic term. In its purest form, it is what happens when you build a city to rural freeway thereby encouraging greenfield development. The new homes create or “induce” demand.

    One can say that an expanded road “induces” demand, but that demand is already latent to some extent. People in Encino would like to go to Santa Monica more often, and once upon a time probably did go to the beach more often than they do now.

    Transit critics love to point out when rapid transit does not lead to reduced congestion on a parallel road. That may be so, but you probably have new riders that can now go to places, grow the economy etc. Similarly, its not totally fair for us transit advocates to criticize road expansions where there is huge, unfilled, “legitimate” latent demand.

    Yes, rapid transit in the Sepulveda corridor makes more sense from a capacity, environmental, equity-enhancing perspective than further road construction.

    As a value proposition, however, one Billion dollars for a new HOV lane (4000 passengers/hour/direction assuming 2 pers/vehicle) is not terrible compared to the ridiculous costs of rail transit construction in this country. A 10 billion dollar rail tunnel would have to carry 40,000 pphpd to roughly equal the road costs. That is why we need to control transit costs, focus on building elevated vs. subway construction and have oversight over transit consultants and scope creep which makes US costs so much higher than Japan or Scandinavia, never mind France or China.

  10. Let’s induce some demand on 980 in Oakland so they don’t try to rip it out any more. But, obviously, not too much, lest anyone demand they rip it out for too many cars.

  11. People often live significant distances away from jobs in a metroplex because the real estate prices to own or rent are unaffordable for many of them – especially for people in lower income service work jobs. And many with kids just won’t live in a postage-stamp sized apartment to get an affordable rent.
    James C. Walker, National Motorists Association

  12. We need to reduce the need to commute.

    Jobs/schools/shopping should be within walking/biking distance of home, we need to adjust land use/redevelopment policy to facilitate this improvement to urban areas. Think: neighborhood commercial zones, fund high quality schools, etc.  

    Additionally, we need a ‘neighborhood based/hyper local’ minimum wage so that every employee can afford housing within walking/biking distance of work.  This will incentivize maintaining/developing a reasonable range of housing in all neighborhoods and establishing new employment near where people already live.  Achieving a goal of 40%-60% of workers living locally would be game changing.

    We also need to address spiraling housing costs… ideas?
    The tired ol’ answers won’t suffice, we need to think out-of-the-box.  These are interconnected issues, it’s not just about traffic, it’s about jobs, security, environment, education, family… quality of life.  At least, the solutions we choose should improve our quality of life, not make it worse. 

  13. In the U.S. money system banks create and issue money for loans. Any activity that does not support loan repayment will not be funded, but suburban development and cars provide a “wealth” of loans. No establishment politician is advocating change in the money system. Therefore, the ridiculous urban transportation design will continue as is.

  14. A toll that hits hard could help….until the next election when even so-called “progressive” political candidates promise to reduce or, even better for them, remove the toll. Seems to work every time.

  15. Putting a toll on a busy road that has been free for decades is unethical and is Marxism at its worst especially for a freeway that bypasses city centers. Your basically advocating putting an expensive toll on a recently widened free interstate highway just to force car owners onto mass transit which in addition to Marxism is Fascism as well. The best thing about the United States and Capitalism is that people have the right to life, liberty, and the pursuit of happiness. If a person chooses to buy a car that is his Constitutional Right to the pursuit of his or her happiness. It is wrong to force people how they can get to places and where they can and how they can live according to the scientific laws of right and wrong.

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