Devil’s Slide Tunnels

As the second and third longest tunnel system in California, these tunnels were constructed to provide a safer, more reliable route of travel between the towns of Pacifica and Montara. Aptly named Devil’s Slide Tunnels, this tunnel system bridges the steep cliff side of Route 1 off the California coast, historically one of the most dangerous roadways in the nation due to land and rockslides in the area.

CTLGroup worked with Kiewit to provide concrete mixture proportion and specification review as well as concrete curing observations.


Civil Infrastructure

Materials & Products


Consulting Services

Concrete + Cement-Based Materials

Concrete Mixture Development & Qualification

Durability & Service Life

Project Specification Review & Development

Mass Concrete & Thermal Control

The tunnels are the second and third longest road tunnels in California, the longest road tunnel currently is in Yosemite National Park at 4,233 feet.

4,149 FT

Northbound Length

4,008 FT

Southbound Length


Project Completion

Learn more about this project

Project Detail Form

Project Detail Form