Stoplights to Mete Out Punishment?

gilrain writes "The San Francisco Chronicle is reporting that traffic engineers have created a stoplight that deals with speeding. According to the article, 'It senses when a speeder is approaching and metes out swift punishment. It doesn't write a ticket. It immediately turns from green to yellow to red.' This is not just a prototype: it is in use now at an intersection in the Bay Area. Does stopping speeders before others serve a purpose other than petty revenge? Is it even safe to change expected stoplight patterns, especially for drivers in a hurry?"