Real estate developers and the municipal codes they’re operating under can’t seem to nail the parking-space formula — putting the right number in the right places — at multifamily housing and commercial projects in cities and suburbs.

And because there’s been flawed policy in place for decades, at least according to some urban-planning groups, there’s actually an ample inventory of parking in most high-density, or otherwise highly traveled, areas. Those spaces just need smarter use.

That solution may lie in part with parking matchmaker apps that, by closing the gap between supply and demand, generate supplemental income for listers, convenience and cost-effectiveness for drivers, and improved neighborhood liveability. The apps aren’t new, nor are they exclusive to the U.S. (U.K.-based Just Park operates there and elsewhere), but their acceptance is broadening, with help from big thinkers on planning.

“One-size-fits-all parking standards from transportation engineers and municipal ordinances apply the same guidelines whether the development sits two blocks from transit or covers the needs of two to three cars in a far-flung suburb,” said Linda Young, a managing director focused on urban analytics at the Center for Neighborhood Technology. The Chicago-based nonprofit has studied the parking patterns of the Chicago; Seattle; Washington, D.C.; and San Francisco metro areas in particular.

In Chicago, for example, rental buildings oversupply 0.27 parking spaces for every unit. Center for Neighborhood Technology

Urban-planning organizations, which previously may have been willing to wait, or had little choice but to wait, for building-code policy to catch up to trends see the “sharing economy” helping to alleviate the problem sooner, especially when used as part of a broader plan that includes mass-transit subsidies, car-share programs and bicycle-friendly design.

Rethinking the parking economy

Parking-rental apps, much like an Airbnb for parking, are helping, including the app from Chicago-based ParqEx. These apps differ from apps that inform drivers of their proximity to available parking garages and lots, such as ParkWhiz and SpotHero. Even Google Maps now lets users know if parking will be easy or limited at their destination.

Instead, these apps play matchmaker between building managers, individual owners and companies that wish to generate revenue from leasing out their parking spaces when not in use. That covers short-term use, like when drivers are headed to a restaurant, and longer-term use, perhaps securing a space near work that’s otherwise empty during the day. ParqEx even received some accelerator support, $20,000, from real estate-minded venture financing source Elmspring, reinforcement that smart parking must be part of smart planning. (It also raised $90,000 from the Milwaukee-based accelerator called gener8tor to secure a total round of $1.3 million in seed-round funding in December.)

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“Rather than paving more land with parking lots, we could help each other by using what we already have,” said Vivek Mehra, chief executive officer of ParqEx, which operates in Chicago, Milwaukee and Madison, Wis., in an interview with MarketWatch.

“If you don’t park in your spot all day, why not list it when you aren’t using it so that someone who needs a spot can use it and you collect supplemental income?” he said. That rings up at an average of $116 a month in Chicago.

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Rival app SPOT, which operates in eight cities, including Miami, Philadelphia and notoriously car-dependent Los Angeles, offers going rates as guidelines on its site. For instance, right now in Boston’s Back Bay, average monthly rental rates are $285 to $325 for a single space, weekly rates are at $75 to $90, and hourly rates run $2.25 to $4.

The legality of renting out, essentially subleasing, private parking spots varies by location. San Francisco famously went after a firm called Money Parking and others a few years ago, charging that the sites were selling first rights to public spots on the street.

Why the need anyway?

The parking formula shouldn’t be so hard to crunch. Yet it is. Building requirements demand a certain number of spaces per resident, often at the behest of neighbors worried that residents in a new development will gobble up scarce street parking. Undersupply can risk real-estate marketability, too. But reality shows that the number of spaces poured often overshoots actual space needs and that parking spots are often underused, by residents leaning on public transportation, for instance, the Center for Neighborhood Technology said. At the same time, empty private spots historically have been off-limits to car-dependent commuters or shoppers who head into a neighborhood.

Parking lots at commercial locations, or even revenue-starved schools, have traditionally remained closed off-hours for trolling drivers headed to a restaurant or a movie. The sharing economy can change that, too. ParqEx’s Mehra confirmed interest from schools among his client base.

The parking supply-and-demand gap bothers the Center for Neighborhood Technology because excess or misused parking capacity hurts neighborhood affordability, the center argues; the cost to manage underused spaces is passed on through rent.

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Technology can provide relatively nimble solutions to matchmaking challenges. Already, ParqEx has cracked one big setback to on-demand sharing: locked or security-protected parking spots hidden behind doors or gates. Internet-of-things capability built into its app opens up 98% of gates and garage doors (after permission is granted), Mehra explained. Security overall can leave some users reluctant, and ParqEx argues that its lease application and vetting elevates the service compared with direct listings from owners on Craigslist or similar personal-ad sites.

For now, acceptance of widespread parking sharing may be increasing at a trickle as growing pains are worked out and as awareness spreads. ParqEx, for example, says it has about 15,000 users; 80% are space seekers and 20% are space listers. So, clearly there is some supply-and-demand imbalance as users warm to the concept. ParqEx won’t release company revenue figures but said it has seen 25% monthly growth in revenue for the last 12 months.

In light of the lumbering pace of policy making in this area, urban-planning groups are embracing the fact that the sharing economy, sufficiently nimble to keep pace with changes in transportation and living habits, is eagerly taking on some of the burden.

“Right after the [2008-09] recession, alternative transportation really had gripped a new generation, whether that was a reduction in number of cars per household, car-free biking or ride sharing, such as with Uber and Lyft — not as an alternative to a taxi, but as an alternative to [owning] a car itself,” added Erin Grossi, CEO of the Center for Neighborhood Technology.

“So preferences change, but cultural measurement systems are often lagging,” she said. “Technology can be out in front.”