California's Ambitious 'Last Chance Grade' Tunnel Project Advances to Design Phase
A 6,000-foot tunnel aims to replace a landslide-prone section of Highway 101, with construction expected to begin in 2031.
California is moving forward with plans for its longest-ever tunnel, a $2.5 billion to $3.5 billion project aimed at replacing a hazardous stretch of U.S. Highway 101 in Del Norte County. The "Last Chance Grade" project, which will span 6,000 feet, has entered its design phase, with final design work, property acquisition, and environmental permitting scheduled to continue through 2031.
The current three-mile section of Highway 101 is plagued by active landslides, unstable earthflows, sheer ocean cliffs, and frequent winter storm damage. This has led to decades of disruptions and costly repairs. Caltrans reported that since 1997, landslide repair projects have cost over $100 million, not including the expenses for ongoing work.
The proposed tunnel alignment is designed to bypass these geological hazards, aiming to reduce recurring emergency repair costs, vehicle operating expenses, and minimize highway noise within Redwood National and State Parks. The park attracts approximately 2.5 million visitors annually.
Caltrans held a public open house to present the designs and provide information on the project. The plan, approved in 2014, is intended to create a safer and more reliable connection between Crescent City and Eureka, a critical route linking Southern California to Oregon.
Construction is tentatively scheduled to commence in 2031, with the completed tunnel bypass expected to open to traffic by 2039. While Caltrans has not yet secured full funding for the construction phase, officials anticipate that the building process will create temporary regional employment opportunities in areas such as heavy civil earthmoving, tunnel support, materials hauling, and traffic management.
Caltrans Director Dina El-Tawansy stated in August that "Last Chance Grade is more than a highway—it is a lifeline for the people, businesses and emergency services of California’s North Coast." She added that advancing the project into the design phase brings the state closer to providing the necessary safe and reliable connection for the region.