For San Francisco, the process of setting parking meter rates has always been a bit like reading tea leaves. It was anyone's guess what the proper fee should be for motorists.
But now, at last, some science and statistics are coming to the rescue to make sure that the city is charging optimal rates.
New "smart" meters installed around the city collect detailed data about the occupancy of each spot. A sensor in the pavement and a computer in the meter know how many cars stop by, and adjust rates accordingly.
If the parking spot is always empty, rates will go down. If it's always full, rates will go up to encourage people to move along quickly and make room for other people.
The new program will start this month in a variety of high-traffic areas around the city. Eventually, the sensors will be connected to a mobile phone app that shows drivers where empty spaces can be found. A warning will pop up if the phone detects that the user is traveling more than five miles an hour while using it.
The prices will fluctuate very slowly -- just 25 cents at a time. The easiest way to anticipate the changing prices is to get a pre-paid meter card, which saves you from having to carry change. Or you could just get a bike.