Here's something you already know: Speeding Kills.
But under California's deadly 85th Percentile Rule, agencies are required to set high speed limits.
Specifically they are required to measure the speeds of existing traffic in free-flowing conditions (i.e. with at least five seconds between cars), then set the speed at the nearest 5 mph increment of the 16th fastest car out of 100 (the 85th percentile speed). In other words, if the speed limit is currently 25 mph, but they measured the 85th percentile speed at 33 mph, the engineers are required to increase the speed limit to 35 mph! There are a few exceptions that allow agencies to reduce the speed limit by 5 mph, but a high crash rate—the rate of fatalities and injuries—can't be factored into the decision-making process.
Legislative Update: April 2018
AB 2363, by Assemblymember Laura Friedman (D-Glendale), allows agencies to round to within 5 mph of the 85th percentile speed, so that agencies can round down if necessary. It also adds the "potential for, and frequency of, traffic collisions resulting in death or injury" as another reason to reduce the speed limit by 5 mph. Learn more: AB 2363 Fact Sheet.
This is a small but important step in the direction of giving California's communities the authority to set speed limits that are safe. But making any changes to the 85th percentile—even for the safety of our most vulnerable users—is going to be a fight.
We can't let the speed demons kill this important bill.