Future-Proofing Parking

By Jake Blumgart

Houston's transportation and land-use patterns are driven by cars. America's third most populous city became the behemoth it is today after World War II, and its built environment reflects that legacy.

But a future looms where the private automobile is no longer king, thanks to the development of autonomous vehicle technologies, as well as ever-improving transit, bicycle, and pedestrian infrastructure and adoption. In a small way, Houston is readying itself — by building a handful of new parking garages designed for conversion to other uses should parking demand drop.

As part of a larger six-story project called the Fairview District, a five-story garage is being built that can transition to housing or offices, should the demand for its original purpose ever dwindle. The company behind the mixed use project, SFT Investments, is not betting against the car. But it is betting that driverless cars could revolutionize personal transportation just as the advent and proliferation of private automobiles once did. If that happens, a lot of valuable downtown real estate could suddenly be open to more profitable development than parking constraints currently allow.

"Everyone is beginning to think about it," says Peter Merwin, who is based in Houston and is the architect and principal in charge of the Fairview District project. He also is a practice area leader for Gensler, an international architecture and design firm.

Merwin doesn't like to make precise predictions about autonomous vehicles. But he wants his clients to understand that there is the potential for profit in building for flexibility. Merwin calls this "future- proofing."

"We can't control the speed of adoption of autonomous vehicles," he says. "But we can control how we react to the industry and the architecture. Now on every project we talk about the marginal costs associated with future-proofing structures."

With driverless technology — paired with app-based hailing services — personal car ownership could decline, perhaps significantly. Especially in dense areas, a small fleet of driverless cars could patrol city streets at all times, available to anyone with a phone. In that case, cities could do with 80 percent fewer parking spaces — according to one study based around Austin, Texas — and that could free up huge swaths of urban land for more valuable uses.

"The reason it's so compelling is that you are working on narrow margins for profit as a developer," says Merwin. "This is a way you can get a greater rate of return on a piece of land because you have minimized the effects of the automobile on the development. You can convert space that would otherwise be a net loss into something that is revenue generating."

Merwin is no dreamy revolutionary, and he does not predict that all parking garages will become obsolete in the near future. But ubiquitous driverless vehicles aren't the only trend pushing garages toward a future with fewer cars. It's possible that as Houston and other sprawling Sun Belt cities turn to densification and urban infill, and consumers call for more walkable spaces, developers will have plenty of incentive to pursue the trend even before autonomous vehicles become widespread. That's why the Fairview District garage will begin life with six retail shops on the ground floor.

"We aren't there yet in the Houston market, but we are planning [convertible garages] into all our mixed use projects," says Merwin. Similar projects are planned or under way in Los Angeles, Seattle, and Denver.

Fairview District, Houston

Five floors of parking in this mixed use building can transition to other uses if parking demand drops.

Source: Gensler

Building Section 1

The design employs flat floor plates and speed ramps, accommodating parking for 38 cars on floors 2 through 6 and retail space on the ground floor. Once the ramps are removed, the floors can be leveled and repurposed for alternate uses.

Source: Gensler

Building Section 2

Opportunities for retail and residential programming open up in a flat-floor parking structure once ramps are removed, as shown in the reconfigured drawing of the Fairview District's garage.

Source: Gensler

Design differences

For now, parking is still in demand and, in most cities, it is required — although a movement toward reducing parking minimums has gathered steam in the past decade. While surface parking lots are easily convertible to a different use, building parking garages for current demand while preparing for the future requires new designs.

For the past half-century, parking garages have been built with low ceilings, sloping floors, and an indifference to natural light. All of that has to be rethought if the garage is to be converted to housing, offices, or another use in the future.

The convertible garage concept "makes a great deal of sense and I'm beginning to see it in developer considerations of the kind of parking decks they are going to build," says Christopher Leinberger, chair of the Center for Real Estate and Urban Analysis at the George Washington University School of Business.

"It's being discussed, and more and more it is being discussed as a certainty," says Leinberger. "I'm not sure if there are any [completed] examples you can point to because of course it takes three or four years from the start of a project to it actually being delivered. This is a relatively new idea that hasn't played out on the ground."

There are three principal areas where developers will need to build differently.

FLOORS

Typically, the floors of a parking garage are sloped, which allows the snow and rain that vehicles bring in with them to trickle toward the drains. Ramps are obtrusive and omnipresent as well, and present another logistical difficulty. A convertible garage model will need to do away with sloped floors and install ramps or car elevators — which can be removed or altered to another use if the building is converted into an apartment building.

CEILING HEIGHTS

Parking garages typically only provide 10 feet or less between the floor and ceiling. Convertible parking spaces will have to measure between 10 and 15 feet instead, as most other uses require taller ceilings.

SUPPORT

Greater reinforcement, such as steel, is needed in the floors of convertible garages because all the accumulated components in a house or office, including corridors, can weigh more than the loads parking garages usually have to bear, says Thomas Fisher, director of the Urban Design College at the University of Minnesota.

Other modifications will be needed as well, including the necessity of future lighting and heating. Enormous concrete pillars common to so many parking garages will need to be maneuvered into places that will not impede future development.

In the garage project at Fairview District in Houston, the design calls for 15-foot ceilings at the ground level, which can accommodate retail, and 10 feet for the rest of the floors to allow conversion to uses like housing.

Designing a garage for a second life down the road adds to upfront costs, of course, notes Fisher. "Some developers don't want to spend extra money on something they don't see as essential. But it's much less expensive to spend a little extra money up front than to tear the building down later." He adds, "Unadaptable parking garages will become a huge liability and will affect the value of a property over the long term."

Rendering of Fairview District's "future-proofed" parking garage. Rendering courtesy Gensler.

What's old is new again

By the beginning of next decade, the first fully convertible garages should be completely operational. Such garages are under construction not just in Houston, but at the World Trade Center in Denver, the soon-to-be-tallest building in Seattle, and a huge housing project in Los Angeles's Arts District.

This idea isn't as novel as it appears. Convertible parking garages were also being built in the early decades of the 20th century, another time when architects and planners didn't know what the future demand for parking would be, says Fisher.

Fisher says that back then, cars were just beginning to assert themselves on the urban scene — a landscape already crowded with pedestrians, horses (and stables), and streetcars. Early garages did not have sloping floors and obtrusive ramps that would hamper their convertibility later. In many cases, automobiles were moved by using an elevator.

"Cars were just becoming common, but they still weren't sure how common," says Fisher. He points to a Saint Paul, Minnesota, building built as a garage with an elevator for cars. It is currently home to apartments, but has done stints as office and warehouse space in between. "So 100 years ago we were in the same position," says Fisher. "We were starting to build garages for cars with the idea that they might need to have another use."

With the future of the automobile again uncertain, perhaps it pays for planners and communities to keep their options open when it comes to parking garages — and the rest of the built environment.

Jake Blumgart is a reporter with WHYY's PlanPhilly.