San Francisco now has a traffic light that detects when someone is speeding and turns red when it senses someone speeding.
In a move unprecedented in the Bay Area, the city's traffic engineers have created a traffic signal with attitude. 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.

Residents and commute-jockeys said Tuesday that the light, which the city plans to unveil today on Vineyard Avenue at the intersection of Montevino Drive, is either an inspired leap into the future or a blatant example of government overzealousness.
Read more about it here and encourage your local commuties to get these traffic lights. Cutting down on speeders is essential if there is to be any safety while cycling. A friend of mine got plowed by a speeder and broke their wrist. Now they have permanent nerve damage to their wrist and they say it hurts all the time.
http://sfgate.com/cgi-bin/article.cg...NG8N61MGG1.DTL