Motorists in San Diego, California will need hair-trigger reflexes to avoid red light camera tickets after a 6-2 city council vote yesterday to increase the number of red light camera tickets 65 percent by eliminating the system's grace period. The change is meant to trap drivers who cross the stop bar 0.1 seconds -- literally, the amount of time it takes to blink an eye -- after the light turns red, generating an estimated additional $200,000 annual profit, bringing the fiscal 2007 total to $1.52 million. The city will further boost the total with a separate plan to add seven more cameras.

San Diego previously had a 0.5 second grace period. Grace times are implemented in general as a means of not trapping drivers for a split-second, technical violation that is visible only to a machine. San Diego's change only affects those who misjudge a light by 0.4 seconds or less.

The number of motorists trapped by such a short grace period is greatest in the first 0.25 seconds after a light turns red, according to a Texas Transportation Institute chart (below). The Texas study also shows that the probability of a right-angle collision in that time period is almost zero at an intersection with a protected left turn lane. "Given a 1.0-second all-red interval, the probabilities also suggest that crossing through vehicles will not start to enter until after about 4 seconds have lapsed," the study states (page 99).

In 2001, a Superior Court judge condemned San Diego's ticketing system, writing: "The evidence obtained from the red light camera system as presently operated appears so untrustworthy and unreliable that it lacks foundation and should not be admitted."