The Missing Middle of Transportation

Micromobility and Autonomy fill a critical gap

I deeply appreciated

Andrew Miller

’s series on the effectiveness of mass transit in cities, and recommend reading the whole thing. Part 1 explains why transit systems are structurally unable to fund themselves, Part 2 explains how we could align incentives and fix this. In Part 3 he reminds us that transportation and land use are the same thing and have to go together. Finally, in Part 4 he considers the role of autonomous vehicles and the role they play in the transit systems of the future.

Miller’s series, especially Part 4, triggered some related thoughts I have about how we understand transportation and land use today, and how technology is going to change it.

In my work with Strong Towns I talk to lots of local advocates from around the country. Many of the people in those conversations are enthusiastic fans of transit. This is often awkward for me, because a lot of what American transit fans are championing makes no sense. I also love trains. I want us to build better, more walkable, more human-friendly cities. But I don’t think that North American-style transit expansion has been successful in achieving that. Transit is only good when paired with walkable, high density corridors. We don’t have many of those, nor a clear path to build them.

That brings me to the YIMBY movement, who are actively clearing the path to allow greater density in our cities. I’m a YIMBY. I think the YIMBY movement and the regulatory reform it’s generating is the most transformative pro-urban change we’ve seen since the Suburban Experiment started. But, sometimes, some of my fellow YIMBYs struggle to see that the NIMBY crowd isn’t only made of loud jerks. There are some actual quality of life problems associated with increasing density, and reasonable people can have concerns about that.

Or as

Matthew Yglesias

put it:

I really think people considering the promise and peril of housing reform would do well to log off, ignore the Marxist geographers, and talk to a normal person who doesn’t like development — because that person is going to tell you that he is worried about traffic.

The problem is specifically: when the level of development increases past a certain point, driving everywhere gets less convenient, but the convenience of walking and transit doesn’t catch up until density gets even higher. There’s a “missing middle” of transportation effectiveness.

The Missing Middle of Transportation

Here’s my mental model:

Effectiveness of transportation modes at different levels of development

In the most rural areas, roads are the most effective transportation option we have. A lot of the land doesn’t have a nearby road, so you can’t get everywhere. Things are really spread out, so it’s not convenient to get anywhere, and walking is impractical. But, if you have a car, it works.

As we move into exurban areas there’s more development so the distances between activities shrinks, but there’s tons of space for parking and hardly any traffic, so driving point to point becomes very convenient. Where you have small clusters of development you can probably walk a little bit too, although it’s still not practical for most trips. Cars are great here!

Our suburban areas are specifically designed to house large numbers of people who will drive everywhere for every trip, and they achieve that goal. There’s more traffic, stoplights, and other headaches to deal with than exurbia, but there’s still parking at every destination and there’s a lot more stuff close by, so overall it’s about the same level of convenience. With more destinations in proximity it’s a bit more feasible to walk as well¹.

At any of these densities, transit sucks. I’m sorry, it’s true. Riding on a bus stuck in traffic is strictly worse than riding in your own car stuck in traffic. Stopping for all the stop signs and stop lights and the bus stops is strictly worse than only having to stop at the stop signs and stop lights. Having to drive to a “park and ride,” then pay to park and pay to ride is strictly worse than being able to drive and park directly at your destination.

When we move up to the older streetcar suburb levels of development, the missing middle that most people really like aesthetically, we have a problem. There are a lot more destinations in close proximity so walking is easier and bus rides are shorter. Not everything is close, so driving would still be the best option for many trips. But at this level of development there’s no longer ample parking, so driving door to door becomes iffy. Will you be able to park anywhere near where you’re going? Or will you be able to park near your own home when you come back? It just depends! The overall transportation situation is less predictable and therefore less convenient.

Now, I’ve lived my entire adult life in the streetcar suburbs of various cities. I think life here is great, and think the tradeoff of “iffy parking” is totally worth it for the greatly improved walkability and neighborhood social life. But it is a tradeoff.

If we keep going up the development ladder we get to our truly urban areas and major destinations. These are our downtowns, stadiums, etc. At these places, traffic is a mess and parking is a giant pain. We’ll drive there and make it work if we have to² but it’s not convenient. On the other hand, if you live in a major urban environment you can walk to most things easily and this is no big deal. Transit works great in these environments, and greatly extends the range you can reach without a car. Occasional Ubers fill the gaps nicely.

For the cities that already exist, this is just describing how the world is right now. Each level of development works differently, the people who live there are generally happy with the tradeoffs they’ve picked, and all is well. But, when we talk about places growing and ascending the ladder of development, it’s a different story.

Remember, suburbia is explicitly designed for everyone to drive everywhere for every trip. Incrementally adding more people to mature suburbs requires building types that can’t provide enough parking for that to work. Worse, if we require keeping the same amount of parking, we have to make the leap to giant buildings that can absorb the cost of parking garages—but if the people who live and work in those buildings still have to drive everywhere the streets can’t handle it. This is a recipe for extremely expensive traffic hell.³

“I’m fine with my neighborhood becoming extremely expensive traffic hell,” said no one ever.

Bridging the middle

The bad news about the missing middle is that the way we do transit today can’t fill the gap. But the good news is, we have new technology that changes the equation. Micromobility and Autonomy fill the gap almost perfectly.

First, Micromobility takes the range-extension and time-saving properties of the skilled cyclist and extends them to mere mortals. E-Bikes, scooters, and the like still require some space to park, so they don’t trivially solve major destination traffic⁴, but in the rest of the city they’re easy to fit. In a missing middle neighborhood, traveling by bicycle or other micromobility is often the most convenient (and fun!) way to get around.

To unlock micro mobility we need safe streets. But we also need safe streets morally and economically, so we should make our streets safe anyway. We have a lot of work to do here, but this one isn’t complicated.

Second, Autonomy brings most of the convenience of point to point driving but partially obviates the parking problem. This one is a little more nuanced, so lets unpack it:

• In our rural and exurban areas I don’t think autonomy can be as good as driving because you have to either schedule a ride or wait a while for a self-driving car to come get you. There are good use cases here, but I don’t think they’re transformative. (Maybe I’m wrong, hit reply or leave a comment and let me know!)

• In our suburban and missing middle areas we won’t have to wait very long for a pickup, so assuming self-driving reaches level 5, this potentially looks like a much cheaper Uber. But as Andrew Miller pointed out, the unlocks for transit service might be even greater.

• In our core urban areas and major destinations traffic is as binding as parking, so I don’t think it’s obvious that autonomous vehicles can be as effective as transit, walking, and Micromobility. I think Uber in NYC gives us a preview of the future—Uber has made “getting a taxi” easier thus made overall transportation more convenient, but it seems to have also made traffic worse.

Taken together, Micromobility and Autonomy—not ideas on the whiteboard, real mass produced industrial tech that exists and is being used around all over the world right now—bridge the gap that’s been holding us back for two generations. We can take advantage of this sea change by removing parking requirements, making our streets safe, and allowing our cities to grow again.

1. Unfortunately it’s not very safe to walk in most of American suburbia.

2. Ugh, football games, why do I like you so much!

3. aka Los Angeles

4. Although we can and should build parking facilities for micromobility just as we do for cars.