Video: Caltrans

Press release from Caltrans District 1:

Caltrans today announced that a landmark project has advanced into its design phase. The “Last Chance Grade” 6,000-foot tunnel project, once completed, will improve travel times and safety through Del Norte County on U.S. 101.

This stunning newly released drone footage highlights the area where the tunnel will protect travelers along this vital corridor from chronic landslide activity.   

“By addressing climate instability and landslides with world-class engineering, California is redefining how we safeguard critical mobility connections,” said California Transportation Secretary Toks Omishakin. “Energized by Governor Newsom’s commitment to major infrastructure projects, this bold tunnel project in the North Region provides enduring resilience for generations to come.”

The landmark tunnel project would mitigate the threat of future long-term closures and save drivers an eight-hour detour through Oregon and inland Northern California should a landslide close the roadway in this area. Repair projects and associated closures create significant impacts for commuting residents, emergency responders, local businesses, commercial freight movement and the tourism industry—vital components to the regional economy in the north state.

The selected alternative would construct an approximately 6,000-foot tunnel east of the existing highway, bypassing areas prone to repeated landslides. At roughly 1.1 miles, the tunnel would be about 1,800 feet longer than each of the twin Tom Lantos Tunnels at Devil’s Slide, which similarly bypass an unstable stretch of coastal highway. This effort marks the largest and most complex project Caltrans District 1 has ever undertaken and would become the longest tunnel constructed in Caltrans history.

The Tom Lantos Tunnels at Devil’s Slide are twin tunnels carrying two lanes of traffic and are approximately 4,300 feet long, as the project spanned 2005 to 2013. Environmental measures included groundwater treatment, excavated-material management, habitat protection and conversion of the former highway into the Devil’s Slide Trail.

At Last Chance Grade, Caltrans anticipates using advanced underground construction technologies to improve safety, precision and efficiency while reducing surface disturbance, including precision excavation equipment, robotic shotcrete and real-time monitoring.

In collaboration with local transportation agencies, Caltrans has delivered three major highway tunnel projects in the past 20 years: the Tom Lantos Tunnels, the Caldecott Fourth Bore, and the Doyle Drive and Presidio Parkway tunnels.

Delivering a project of this scale in a rural coastal county presents considerable engineering, environmental, permitting and funding challenges. Caltrans remains focused on keeping the project on schedule, with construction currently anticipated to begin in 2031.

The completion of the Project Approval and Environmental Document (PA&ED) phase included environmental studies, the completion of the draft and final environmental document, engineering analysis, public and agency coordination, the selection of a preferred alternative and the acquisition of the formal approvals needed before detailed project designs can begin. “Last Chance Grade is more than a highway—it is a lifeline for the people, businesses and emergency services of California’s North Coast,” said Caltrans Director Dina El-Tawansy. “Advancing this tunnel into the design phase brings us closer to providing the safe, reliable connection Del Norte County and travelers deserve.”

The Last Chance Grade Project is crucial to the continued vitality and economic future of Del Norte County. Landslides have plagued this stretch of highway for decades, requiring repeated repairs, traffic delays and emergency closures. 

Caltrans is working diligently with local and statewide stakeholders to deliver the dependable connection Del Norte County while maintaining the momentum necessary to fund and construct this project.

Current CTC materials identify about $225 million for design and right-of-way support, with construction estimated at $2.5 billion to $3.5 billion. Construction funding has not yet been secured, and Caltrans expects to pursue a mix of federal, state and financing opportunities during design.

The project’s oversight approach includes specialized tunnel designers, early Construction Manager/General Contractor involvement, independent cost estimating, geotechnical investigations and phased design checkpoints to manage risk and refine costs.

“This significant progress highlights our sustained commitment to delivering a safe and reliable solution for people who rely on travel through the Last Chance Grade,” said Caltrans District 1 Director Matt Brady. “Projects of this magnitude require a bold, shared vision from all stakeholders, and we appreciate their support as we advance this effort to the design phase.”

“A project of this magnitude requires diligently working with community stakeholders to develop the best options to preserve the vital coastal U.S. Highway 101 corridor for the West Coast and Del Norte and Humboldt counties,” said U.S. Representative Jared Huffman. “Caltrans admirably continues to work with my Last Chance Grade Stakeholders Group to advance this project and ensure the best possible outcome is achieved. I strongly urge that collaboration to continue to reach consensus on important issues.”

“Getting this damn project off the ground has been an all-hands-on deck effort,” said State Senator and California Senate President Pro Tempore Emeritus Mike McGuire. “But with major state investments over the past five years, we’re closer than ever to solving one of our biggest transportation challenges on the North Coast. With the environmental review for the project now complete, the state is ready to move forward with another $185 million investment that will complete the design phase. This means that Last Chance Grade will be shovel ready for construction by 2031. This is big news for all of us who call Northern California home.”

“Completing the environmental phase marks the point where the permanent solution Del Norte County has pursued for decades moves into detailed design,” said Del Norte County Supervisor Chris Howard. “Last Chance Grade is the lifeline connecting our communities, emergency services, businesses, and visitors to the rest of California, and a long-term closure would have consequences our region simply cannot absorb. This milestone reflects years of sustained advocacy by the Del Norte County Board of Supervisors, together with the work and support of Caltrans, state and federal elected officials, tribal governments, agencies and community partners. We must now maintain that urgency, secure construction funding, and finally build it.”

During this next phase, Caltrans will further develop design concepts for several project elements, including the tunnel, portals, connecting roadway, bridge, drainage, safety systems and operations and maintenance facilities. Work will also continue with permitting, mitigation implementation, geotechnical investigations, cost refinements and securing project funding.

Construction is expected to create temporary regional jobs in areas such as heavy civil and earthwork, tunnel support, hauling, material supply, traffic control and restoration. A specific job estimate has not yet been developed.

Caltrans is also working with local tribes to expand Native American hiring and workforce development, including studying successful tribal hiring programs elsewhere, coordinating with the Yurok Construction Corporation and exploring educational opportunities for tribal youth.

The project has advanced through years of engineering, environmental study and coordination with tribal governments, agencies, elected officials, community members and other partners. That continued engagement will remain essential as Caltrans works toward construction.

Additional information and project updates are available at lastchancegrade.com.

For more information about transportation and other infrastructure projects funded with state and federal investments, visit build.ca.gov.