So it was nice to have an excuse -- a presentation at the CONSTRUCT 2019 conference in the Washington, DC, area last month -- to look at how parking and zoning influence each other.
Starting in the 1920s, American cities had to cope with an exponential influx of cars. Parking lots and garages sprung up ad hoc in response to the new demand. About the same time, municipal zoning codes made their debut as a reaction against the high-density, mixed-use neighborhoods created by urban migration and industrial expansion. Parking and zoning didn't really come together until right after World War II, when zoning-mandated parking minima were promoted as the solution to "the parking problem."
Within the past decade, U.S. cities have realized that copious asphalt is actually the opposite of what people want in urban life, and many cities have sharply reduced parking requirements to encourage the very same high-density, mixed-use neighborhoods that so troubled our predecessors a century ago.
In my research, I came across some unexpected finds:
In cities as different as Des Moines, Seattle, and Philadelphia, downtown parking use typically peaks at about 65% of spaces filled.
While millenials do drive less than previous generations, that has been offset by higher percentages of drivers in older age groups.
The amount we're driving, as measured by vehicles and miles driven per household, may have fallen a bit since before the great recession, but it's now roughly on par with where we were in the mid-1990s.
Uber, Lyft, and bike- and scooter-share programs aren't going to reduce parking demand much: only 1 in 5 of those trips substitute for a personal car. Rideshare vehicles only carry passengers 63% of the time, increasing congestion and total vehicle-miles in cities.
We have a lot of parking! In some cities, 11 off-street spaces for every household. Even the downtowns of compact, mid-size New England cities like Providence use 15% to 20% of this prime real estate as surface lots. These large areas of impervious asphalt and concrete measurably increase pollution, stormwater runoff, and urban temperatures.
Since moving to our new office, my short commute to DUAL, has been through the heart of the American Urban Grayscape. My walk of just 750 feet, takes me through and past 10 separate parking lots, with spaces for (by my rough count) 265 cars.
The most useful parking lots are multifunctional spaces that accommodate more than just cars. Other than my kids doing a few laps in bike-riding weather, these do not. Some fill out with workers' cars for a few hours on weekdays, but most spots are empty most of the time. That's bad for the streetscape, the environment and the tax base, because a large portion of the taxed value comes from "improvements," i.e. buildings.
It's time to seriously consider meaningful incentives for developing lots as buildings or green space, and disincentives for keeping them gray. There's so much potential for beauty (and gold) just under the asphalt.