To prevent shortages, some cities have begun to adjust their meter rates (using trial and error) to produce about an 85 percent occupancy rate for curb parking. The prices vary by location and the time of day. Drivers can usually find a vacant curb space near their destination, and the search time is zero. Cities can adjust the price of curb parking in response to demand to keep roughly one out of every eight spaces vacant throughout the day. Right-priced curb parking can eliminate cruising.

The balance between the varying demand for parking and the fixed supply of curb spaces is the Goldilocks Principle of parking prices: the price is too high if too many spaces are vacant, and too low if no spaces are vacant. But when only a few spaces are vacant, the price is just right, and everyone will see that curb parking is both well used and readily available.

Beyond the transportation and environmental benefits, performance-based prices for curb parking can yield ample revenue. If the city uses a share of this money for added public services on the metered streets, residents and local merchants will be more willing to support charging the right price for curb parking. These funds can be used to clean and maintain sidewalks, plant trees, improve lighting, remove graffiti, bury utility wires and provide other public improvements. Returning the meter revenue generated by a district to the district can persuade residents, merchants and property owners to support right-priced curb parking.

Redwood City, Calif., for example, sets its downtown meter rates to achieve an 85 percent occupancy rate for curb parking (the rates vary by location and time of day, depending on demand). Because the city returns the revenue to pay for added public services in the metered district, the downtown area will receive an estimated $1 million a year for increased police protection and cleaner sidewalks.

The Redwood City merchants and property owners all supported the new policy when they learned what the meter revenue would help pay for, and the City Council adopted it unanimously. Performance-based prices create a few curb vacancies so visitors can easily find a space, the added revenue pays to improve public services, and the improved public services create political support for the performance-based prices.

If cities want to reduce congestion, clean the air, save energy, reduce greenhouse gas emissions and improve neighborhoods — and do it all quickly — they should charge the right price for curb parking, and spend the resulting revenue to improve local public services.

Getting that price right will do a world of good.