California is building a $400M shield for Yosemite's most dangerous highway

California is building a $400 million, 675-foot rock shed to protect a vulnerable stretch of Highway 140 where the Ferguson Slide buried the road in 2006. The design is a vaulted concrete arch made of massive, precisely fitted segments - about 6,000 tons of concrete and rebar - that function like a “tunnel with windows” to let traffic pass safely while withstanding catastrophic rock avalanches and being buried up to 40 feet. Caltrans is batching concrete on site and erecting large piers intended to last a century; the agency expects the restored segment to reopen in roughly five years. The project replaces a temporary bypass of bridges controlled by traffic lights and aims to keep this critical access route open even under extreme slope failures.

The highway carries millions of visitors to Yosemite and supports the tourism economies of towns such as Mariposa, El Portal and Midpines, but the landscape that makes the route scenic also makes it precarious. Residents and workers welcome the engineering feat yet fret that climate change and an expected El Niño will increase slides elsewhere along 140, leaving other stretches still exposed. Historic accounts show the road’s risky construction a century ago, and locals compare the canyon’s hazards to notorious coastal failures; the shield solves a massive local threat but does not eliminate broader regional vulnerability.