No one knows more about parking than UCLA’s Donald Shoup, the so-called “prophet of parking” and author of the 2005 book The High Cost of Free Parking. Shoup’s insights have led to a greater appreciation for the benefits of charging a market rate for parking—namely, less time spent searching for a spot, and thus less traffic congestion. In a piece for ACCESS magazine, adapted from an op-ed in the San Francisco Chronicle, Shoup points to several parking innovations that every city should consider adopting.

1. Pay-By-Plate Technology

Many if not most big cities have done away with individual parking meters, replacing them with kiosks that accept credit cards. Shoup suggests taking the additional step of making license plate numbers part of the parking-kiosk transaction.

Pittsburgh began citywide implementation of pay-by-plate meters in 2012. Drivers punch in their plate numbers at the kiosks, then pay by credit card or cash, then go on their way—no need to go back to the car and display a receipt in the dash. Better still, drivers can re-park within the same zone without re-doing the whole transaction. Enforcement officials have an easier time, too; they simply scan a plate, see if it’s paid, and move on or print a ticket.

The system led to a reported increase in parking revenue for Pittsburgh, even as it led to a big decline in the number of tickets being issued. That might sound contradictory, but it actually makes sense. As pay-by-plate technology made it easier to pay—especially when combined with smartphone payment apps—more people actually paid for parking rather than risk a ticket (which might never be issued or paid anyway).

Shoup also points out that pay-by-plate kiosks make it easier for cities to customise parking discounts for some drivers or surcharges for others. More on that below.

2. Pollution Surcharge

To encourage cleaner cars and improve local air quality, Madrid imposed pollution-based parking fees that vary based on a car’s environmental impact. The new charge is applied via pay-by-plate technology: drivers input their plate numbers, which tells the city system the make and model of the car, which then spits out a parking rate based on emissions. Hybrids, electrics, and fuel-efficient cars reportedly get up to a 20 percent discount; gas guzzlers pay up to a 20 percent surcharge. Here’s Shoup:

3. Length-Based Fees

[infobox]According to the head of Madrid’s sustainability division, “We thought it would be fair if the cars that pollute more pay more, and compensate those who use more efficient vehicles.”[/infobox]

While we’re charging cars based on emissions, why not charge them based on length, too? After all, curb space is a limited commodity along city streets, and not all cars occupy it equally. (Additionally, shorter cars tend to be more fuel-efficient.) Shoup has worked out a basic framework for the length-based charges, ranging from a 56 percent discount for those cute little Smart cars to no discount for a Rolls Royce. “Most people who can afford to buy a longer car can probably afford to pay more to park it,” he writes.

4. Special Resident Rates

In Miami Beach, residents pay a lower meter rate than non-residents and tourists pay—$1 and $1.75 an hour, respectively. That fee (again, implemented with the help of plate-kiosk technology) might seem unfair in the abstract. But Shoup justifies the approach because local residents, unlike visitors, already pay taxes to maintain streets and parking enforcement services. The system also encourages people to shop closer to home, which in turn reduces driving and congestion.

5. New Local Services

Along similar lines, parking revenue doesn’t all have to go into the city’s general pocket—it can be invested back into the neighborhoods where it originated in smarter ways. A few years ago, for instance, Ventura, California, installed parking meters where none existed previously, but used the revenue to pay for local street patrols as well as public WiFi. This approach fosters political good will among shop owners who typically oppose meters, as well as drivers who tend to see meter hikes as taxpayer gouging.

Shoup concludes:

[infobox]By changing the politics of parking, cities can meter more of their valuable curb space, producing more money, less traffic, cleaner air, and a cooler planet. Parking meters can then do a world of good.[/infobox]

This article originally appeared in CityLab.