Over a mile of guardrails will be replaced next summer in 13 places in West Marin. Locations include Marshall-Petaluma Road, Point Reyes-Petaluma Road, Tomales-Petaluma Road and Panoramic Highway. The $961,200 project is fully funded by a federal grant from the highway safety improvement program. The locations were chosen based on a five-year study of collision trends in Marin, which looked at all 2,756 crashes from 2012 to 2016, with a specific focus on collisions that killed or seriously injured someone. That study found that unincorporated Marin ranks first out of California’s 58 counties in terms of the percentage of car accidents resulting from speeding. Solo vehicle crashes were the most common crash type and represented 23 percent of collisions in which someone was killed or seriously injured.