This Week in Urbanism: Road Diets | NOW AVAILABLE TO STREAM

Missouri Metro’s weekly podcast, This Week in Urbanism, just released its second episode titled “The Problem with the Suburbs”. You can listen to the podcast on Spotify Fridays at 7AM and supporters on Patreon have exclusive access to the content one day early. If you would like to support the channel, head over to

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You’re listening to This Week in Urbanism from Missouri-Metro.

I’m your host, Brian Adler. This Week in Urbanism is designed to bring you up to speed on the latest in urban developments, infrastructure, policy, politics, rumors, and more that influence the urban experience in St. Louis. So, stick around and subscribe so you don’t miss the Friday morning shows as we take you on a journey showing how St. Louis is moving forward. If you want to listen a little early, check out our Patreon supporter page at to support this podcast.

Today is February 18th, 2022, and today, we’re going on a diet. Or should I say, a Road Diet?

Here’s a question for all my listeners – How many of you regularly drive on these massive city roads with, say, 6-8 lanes total? I can think of several here in St. Louis where we have just massive roads with several lanes going in each direction, and boy, it’s utterly insane.

But that’s just the price to pay for reducing traffic, right? Surely adding lanes reduces congestion, right? Common sense, it seems, may just be a common trap for bad policy.

*Insert Traffic Noise*

Traffic is cringeworthy. It gives us anxiety, makes us late for work, and probably makes us all pull our hair out. It also leads to some pretty darn bad behavior. A 2019 study from the National Institute of Health showcased a U-Shaped curve indicating that increased traffic congestion also leads to increased traffic accidents. It’s not too hard to see how that might be the case when mere inches separate cars amidst stop and go traffic while tensions and anxiety run high. I probably don’t need to work all that hard to convince you that traffic congestion is bad when we all hate long commutes, but I also definitely want to point out the impact of traffic congestion on the environment too. There’s a standard emissions curve that showcases vehicle speed in relation to carbon emissions, and the picture it paints isn’t very pretty. What ends up happening is that cars stay on the road for longer idling or moving slowly, which exacerbates the impact on the environment because it is at very low speeds that vehicles release a significantly higher amount of carbon dioxide. So inefficient speeds combined with longer times on the road leads to worse air quality and more greenhouse gases in the atmosphere.

We all probably want to tackle this, and it’s absolutely frustrating to do nothing. Generally, we think about traffic as an issue directly connected to the number of lanes and considering the number of lanes really becomes the only variable that cities and neighborhoods consider changing. It makes sense, but, as I’ll discuss in a moment, only furthers auto dependency, and digs the community deeper and deeper into a worsening traffic congestion problem.

You may not yet believe me, and you may have previously advocated for more lanes. Don’t stop playing this just yet! I’m not coming after you, but here to shed light on this solution not giving us the solutions that we all want. In fact, before diving deeper into academic studies and progressing in my graduate program, I clearly remember advocating for more lanes to reduce traffic. So, there’s no judgement here.

Let’s start with the recognition that this science and research is not new. Researchers have been looking into traffic for decades simply because it has been a continually worsening problem that we all hate. In 1989, The Southern California Association of Governments concluded that adding lanes or creating double decker freeways would have no impact on traffic save for a cosmetic appearance of solving a problem that isn’t being affected. Crazy, right? How could we build so much more capacity only to not have a large impact on the problem?

Well, a study from UC Berkeley studied traffic in 30 California counties between 1973 and 1990 which showed that each 10% increase in traffic capacity, so essentially increasing lanes, traffic congestion increased by 9% within just four years. An analysis of dozens of studies suggested a very similar result finding that within just a few years, a 10% increase in capacity leads to a 10% increase in usage and vehicle miles traveled. In the few studies that showed reduced congestion, it was a very small benefit compared to the amount of space that simply was absorbed by increased usage. This is problematic for so many reasons. We spend so much time and money trying to relieve congestion, only to end up with stagnant or increased traffic and emissions. That sucks!

What occurs is something called “Induced Demand”. There are some great resources to understand how this process works, and I’m going to do my best to summarize the core elements of induced demand. We’re going to dive into some simple economics for a moment.

Let’s start here. In introductory economics, one of the first things you learn about is the supply and demand curve. For those unfamiliar, imagine a graph with price on the y-axis (that’s the vertical one) and quantity demanded on the x-axis (that’s the horizontal one). There’s a curve, called the Demand Curve, that showcases for most normal goods that quantity demanded of a particular item is low when price is high and high when prices are low. In other words, demand is elastic in that it is responsive to price.

The same is true for driving. The cost of road travel decreases in the initial months after a road expansion is completed. That’s because congestion initially decreases, so you spend less time commuting and thus spend less on gas commuting. There is also a lower opportunity cost for your time as the total time spent commuting is lower. So, there is less of value you could do in that shorter commute than, say, if you spent 2 hours on the road instead of working for a certain wage or spending time with family, which is probably worth some value to most people. This reduced cost makes driving more attractive and INDUCES more demand, pushing more drivers onto the new roads that they hear are reducing commute times. There is also a body of research that showcases how driving demand really is elastic! So, we’re not just making this up.

In effect, traffic ends up being diverted toward the new lanes. In addition, it induces traffic that did not occur in the first place because driving is initially more competitive than other options, or at least more so than just before the road expansion occurred. As such, new vehicle trips are generated in addition to diverted trips.

Once we understand how induced demand ultimately can increase road usage and traffic, we can use the same framework to perhaps work toward the real and perhaps less ideologically comfortable solutions.

It may seem like ages in this podcast episode since I seemed to arbitrarily say something about roads and diets, but we’re finally getting back to that point. An emerging strategy that cities have been using to calm streets is really the exact opposite of what we’ve been talking about. Cities have been employing “Road Diets”, essentially purposefully reducing capacity usually in the form of lane reductions. Say you have 2 lanes in each direction, in some of the better road diets you may see this reduced to one lane in each direction for cars, one lane for a bus-rapid-transit route, and protected bike lanes. You still have the same amount of space, but you’re adjusting it to serve more uses and reduce room for individual cars. Ultimately, you will often find that road diets move more people. By making transit and biking more convenient, they become more attractive and induce demand for those services. On the other hand, you can dissuade demand for driving by making the cost of road travel increase. Demand decreases and traffic ultimately decreases as well. This is related to behavioral economics and is well rooted in empirical research. People will switch their behaviors to public transit, biking, carpooling, biking, or even moving closer to their jobs.

I’m not making this stuff up. A 1998 study combined 150 sources of evidence and 60 case studies from the US and other similar countries and found that traffic was significantly reduced when road capacity had been reduced, of which less than half could be detected simply being diverted to other roads, indicating that behavior had really changed. The study concluded that reallocating bloated roads for other purposes like pedestrians, bikes, and more can improve the experience for all uses without significantly increasing congestion. This doesn’t mean that everyone will change their behavior, but that many people will and may even find better solutions along the way.

Of course, this has a bunch of real-world positive externalities. Businesses will find calmer streets to place their tables against. Room for protected bike lanes saves lives, induces healthy and environmentally friendly demand for biking, and fewer pedestrians will be hit. Less traffic means fewer greenhouse gas emissions and fender benders along the way. Dedicated transit lanes mean reduced costs, better access, opportunity for transit-oriented development, and of course, fewer emissions.

This isn’t a pipe dream, folks. This is the future and the present. It’s happening now, and despite lots of pushback when these plans are proposes, communities where road diets take place will often be the first to tell you after the fact how much of a positive difference it makes.

Here in St. Louis, we just saw a major road diet completed on Hampton from Gravois to Chippewa – a big stretch of road! The road diet entered the public consciousness several years ago after jay drivers were smashing into businesses and harming pedestrians. As the owner of Abigail’s Gift Boutique mentioned in a St. Louis Public Radio feature, a car smashed into her business at 45 miles per hour alongside Hampton a few years ago and ended up destroying most of the store. Thankfully none were injured. Of course, she mentioned that nearly every day she heard the screeching sound of accidents outside. Just a couple years ago, a cyclist was hit and killed along this stretch as well. This was not a safe place to drive.

The Road Diet took the formerly four-lane road and limited traffic to one lane in each direction with a center lane and wider parking lanes. Honestly, in my view, they could have done a whole lot more to provide incentives to other forms of transportation, but this is still a step in the right direction. The owner of Abigail’s Gift Shop already sees more pedestrians outside and feels her commute is probably affected by less than a minute. She mentions that her customers feel significantly more comfortable crossing the street too.

This is just a start, and a whole bunch of St. Louis arterial roadways are congested and frankly dangerous for drivers, pedestrians, and bikers alike. Kingshighway, for example, would be an absolute nightmare to bike on. I do not bike on this street, and I bike around the city a lot. I avoid it, and my wife does too because we don’t want to die. But it’s not just biking, the sidewalks feel plainly unsafe as cars recklessly speed by or perform gymnastics around one another to see who can hit the next red light the fastest. Taking the #95 bus along this route is also an exercise in frustration, as you must cross a horrible street to reach your destination half the time with far too few crosswalks, your bus gets cut in front of or not let out of its lane, or otherwise finds itself in the same gridlocked traffic as everyone else.

To make our cities better and more livable, we must be able to think outside the box and work toward solutions that don’t fit the mold of common sense. We have empirical research, and a lot of it, that showcases the standard strategies of reducing congestion simply do not work. Our streets should not be endless lanes of car-traffic. Our cities should be flexible and meet the needs of all types of commuters, and they should do so safely. While it may surprise some listeners, not everyone wants to drive a car, and already many people commute by other means. We can cater to them and make traffic better.

Remember, solutions aren’t always comfortable or expected. But that’s life. Life is full of nuance, and we’re lucky that life is full of researchers who choose to investigate these practical topics. So, here’s what I want you to do – next time you see plans to address congestion, go to those meetings. Be bold enough to stand up to bullshit anecdotes because our cities don’t need more of those. We have evidence backed solutions that have been formed for decades, and we simply don’t have the time to be held back by traditionalists whose vision for cities will trash our planet, kill pedestrians and bikers, and harm businesses. If this sounds harsh, well it is. People don’t realize the importance of this topic until you do your research and see how many people have died and will continue to die until we get our stuff together.

People, this stuff is serious. If we want to combat climate change, address equity, provide for opportunity, and save lives, then we must be committed and stop messing around. I’m not talking about this to simply make our cities look prettier or to make a silly suggestion to reduce traffic, but to address real problems on top of them. So, show up to these meetings and be the voice of reason that we need to change hearts and minds. We have direct, local democracy in cities so let’s use it – because we need a seat at the table.

This Week in Urbanism, I want you to help me create a better world. Let’s get on this, together. This was our mission last week as well, but we have a lot on our plate.

Stay tuned for an exciting interview with a Dr. Todd Swanstrom, a leading academic who studies St. Louis, gentrification, neighborhoods, anchor institutions, and more next week.

Have a great day, St. Louis. To the rest of the country, we’re here in the middle, finding our place in the 21st century. Get ready.

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