The current section is News & Media

Caltrans Completes Devil’s Slide Tunnel Construction

Caltrans cut the ribbon today for the first new highway tunnels in California in nearly 50 years and the longest tunnels in the state — the new Devil’s Slide Tunnels on State Route 1 in San Mateo County. The tunnels will officially open to the public tomorrow morning.

“Today, we mark the start of a new chapter for both Caltrans and the local communities,” said Caltrans Director Malcolm Dougherty. “No longer will local residents and businesses have to worry about severe winter storms closing the road and disrupting their lives.”

Under construction since 2007, the $439 million project features two 4,200-foot long tunnels, 32 jet-powered fans for ventilation, and 10 fireproof shelters between the tunnels to protect the public. The project includes a 1,500-foot north approach with twin 1,000-foot parallel bridges, and a 1,000-foot south approach road, as well as a nearby operations and maintenance facility. Tunnel portals are designed to blend in with the natural environment.

Located about 15 miles south of San Francisco between Pacifica and Half Moon Bay, the new tunnels bypass a curvy and unstable section of SR-1 built in 1937 that has been plagued by rockslides and that repeatedly erodes and collapses.

“Devil’s Slide has been an enormous undertaking in difficult terrain,” said Brian Kelly, acting secretary of the Business, Transportation and Housing Agency. “Ingenuity, will, and perseverance combined to get this project done. The new tunnels are state of the art structures that blend well into the beautiful, natural surroundings on this stretch of Highway 1. Thanks to the work of the men and women who dedicated themselves to completing this project, motorists and emergency responders will have a safer journey from this day forward.”

Caltrans has closed the road many times for extended periods to make emergency repairs, hampering local residents and businesses. Each closure turns a 7-mile drive from Pacifica to Montara into a 45-mile detour. One of the longest closures happened in 1995 — it lasted 158 days.

MTC Chair Amy Worth was on hand for the opening celebration today. “In addition to expressing MTC’s gratitude to the engineers and construction workers who worked on the tunnels and bridges — as well as to the family of the late great Congressman Tom Lantos who worked so hard and for so long to secure the federal funding that made these magnificent new structures possible — I also want to thank the Coast Side residents and businesses who advocated so passionately, so persistently and so effectively for a safe and enduring solution to the travel challenges along Highway 1, and who have waited so patiently for this great day to come! “

The old 1.2-mile stretch of roadway will be converted into a non-motorized public facility offering breathtaking views of the Pacific Ocean.

For more information about the tunnels,

Tom Lantos Tunnels

Submit your comment

In order to receive a reply to your comment, please provide an email address.

Plain text

  • No HTML tags allowed.
  • Web page addresses and email addresses turn into links automatically.
  • Lines and paragraphs break automatically.