A tunnel with a road from the outside.

California launches design phase of $2.1B coastal tunnel project

July 9, 2025

The California Transportation Commission has jumpstarted the Last Chance Grade Project into the design phase with a $40 million injection. With the design phase set to begin, construction on the $2.1 billion Del Norte County tunnel project is set to begin in 2030.

The California Department of Transportation (Caltrans) recently selected the project’s preferred alternative, opting for a 6,000-foot underground tunnel that bypasses the landslide complex and realigns the highway.

Avoiding the landslide area protects the route from seismic activity, chronic landslides, coastal erosion and impacts on old-growth redwood trees, according to project officials. Once completed, the tunnel will be the longest of its kind in California history.

The tunnel will feature one lane going in each travel direction, eight-foot shoulders and a separate bicycle and pedestrian facility. Caltrans will also build an Operations and Maintenance Center to meet ongoing maintenance needs. Compared to the other alternatives considered, the tunnel will provide a significantly more reliable route along the coast for years to come.

The three-mile section of Highway 101 is a critical connection between Del Norte County and the rest of the state. However, it has been deteriorating for years, vulnerable to landslides and failures. Inclement weather has significantly contributed to the road’s condition as it has crumbled, slid and washed away by swathes of heavy rain.


Photo by Ansel Lee from Pexels

Adam Rollins

Adam Rollins brings his expertise as a Researcher and Writer to the Managing Editor role for several of SPI's key publications, including Government Contracting Pipeline, Texas Government Insider, and the latest addition, Government Market News. With a rich background as a freelance Content Specialist, Adam has honed a passion for learning and information gathering, delving into various industries. His research and writing have spanned a range of topics, from artificial intelligence (AI) technology, conservation, and project outsourcing, to managed IT services and software development.

Holding a bachelor's degree in English from Texas State University, Adam's proficiency in message development is complemented by his robust research skills and seasoned writing experience. These attributes make him an invaluable asset to SPI, ensuring the delivery of insightful and impactful content to the company's clientele.

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