How Wide the Streets

Somewhere there’s planning
Show me the deets
Somewhere there’s drafting
How wide the streets

—Folk song of unknown origin

I’ve previously discussed street width primarily in the context of the Midway Village project, where the streets are designed for people rather than for vehicles. In such a context, there is essentially no lower bound on street size aside from issues of aesthetics and comfort.

When implementing small streets urban planning on a larger scale, however, vehicles must be taken into account. Even a walkable, transit-rich city needs to be accessible and navigable to delivery vehicles, emergency vehicles, and yes, people who drive cars. Creating a pedestrian paradise and removing all the subsidies we provide to drivers will not completely obviate the need or the desire for automobiles. Cars, after all, are useful things and can provide a large societal benefit once we remove the goggles that make every inch of urban real estate look like a nail to the car’s hammer.

So how do we achieve a harmonious blend of pedestrian dominance and vehicular accessibility? The answer in some sense already exists within the framework of our current cities. In Chicago’s grid, not all streets are created equal. Every half mile in each direction, there is a wide arterial road designed to handle a high volume of two-way traffic. Between these lie smaller, typically one-way streets designed primarily for use at the beginning and end of longer car trips. This is a sensible system, at least in the (totally insane) context of a city designed for automobile use. It just needs to be scaled down.

The smaller streets of modern-day Chicago should be replaced by very narrow streets, in the vein of those I’ve proposed for the Midway Village. These streets should, for the most part, not prohibit vehicle traffic, but should by design render vehicle traffic slow and rare. While delivery and emergency vehicles will need to be able to access these streets as usual, personal automobile use will be curtailed by the absence of parking.

What about the larger arterial streets? They should have one vehicle lane in each direction, with ample (but not oversized) sidewalks on either side, and definitely no on-street parking. Nathan Lewis shows an excellent example of this sort of street in Tokyo. As Lewis argues, there’s no room for individual buildings to have off-street parking, but the market could provide parking structures as needed. These arterial streets could be spaced more closely than Chicago’s giant arterial roads: one per quarter mile would be reasonable. Locating parking structures on such streets would suffice to keep most car owners and car sharers off the really narrow streets.

Bicycle advocates might object at this point. Where are the bike lanes? Bike lanes are an important feature of our city’s current transportation infrastructure, but I think their costs would outweigh the benefits in a small streets urban design. Both the really narrow streets and the arterial streets, while designed specifically for pedestrians and motor vehicles, respectively, would be much more hospitable to cyclists than today’s sidewalks and arterial roads. Dedicated bike lanes would not add much value for cyclists.

The costs of bike lanes, on the other hand, are large. Grid Chicago’s Steven Vance gives us a good look at what goes into street width calculations, at least under the current regulatory regime. Travel lanes take up 10 feet each. Excessive, perhaps, but let’s go with it. So 20 feet for car traffic. With 5-foot sidewalks, this brings us up to 30 feet. Installing 5-foot bike lanes would bring the total width up to 40 feet. This is still quite narrow compared to most of our streets today. But to put it another way, with arterial streets placed every quarter mile, bike lines would take up 1.5% of our urban real estate! We could place bike lanes on only some arterial streets, and perhaps there are places where it would make sense to do so. But overall, bike lanes would not have a significant role to play.

Of course, retrofitting a city like Chicago with a small streets design would require an enormous effort, involving plenty of infill development. This is why I advocate primarily for urban experiments like the Midway Village. But a small streets village shouldn’t be thought of as an isolated novelty. With sufficient political will, the same principles can guide the (re-)development of an entire functional city.

About Evan Jenkins

I am an algorithmic trader and occasional writer living in Hyde Park, Chicago. I recently received my PhD in mathematics from the University of Chicago.
This entry was posted in Automobiles, Bicycles, Small Streets. Bookmark the permalink.

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