Wikipedia
SFpark is San Francisco's system for managing the availability of on-street parking. Taking effect in April, 2011, the program utilizes smart parking meters that change their prices according to location, time of day, and day of the week, with the goal of keeping about 15% of spaces vacant on any given block. The San Francisco Municipal Transportation Agency launched the system with congestion mitigation funding from the Federal Highway Administration in July 2010 as a fallback from a downtown cordon. It is one of several such systems in the world. The City of Calgary, Canada and the Calgary Parking Authority with their ParkPlus system have been using a similar demand based pricing model since 2008.
The system seeks to reduce the time and fuel wasted by drivers searching for an open space. Parking usage is monitored via sensors placed in the asphalt, and the availability and prices can be checked via SFpark.org, iPhone and Android apps, and cell phone. Prices can range from a minimum of 25¢ to a maximum of $6 per hour during normal hours, with a $18 per hour cap for special events such as baseball games or street fairs. , prices range from 25¢ to $6.00 per hour during normal hours. In addition to the on-street parking, fourteen city-owned garages are included in the program.
This concept of market-based variable pricing or "performance parking" has long been advocated by transportation researcher Donald Shoup, now an adviser on the project.