By rosebell
Caltrans has progressed the Last Chance Grade Tunnel to the design phase, moving the proposed road project in northern California closer to construction.
The progress follows completion of the environmental approval phase, public consultation and the selection of the preferred alignment.
The tunnel would take US Highway 101 east of the existing road, bypassing areas prone to landslides which can force drivers onto an eight-hour detour through Oregon and inland northern California.
The 1.83km-long bore would be the longest tunnel and most complex project Caltrans District 1 has undertaken. Construction is scheduled to commence in 2031.
The delivery approach will include specialized tunnel designers, early construction manager/general contractor involvement, independent cost estimating, geotechnical investigations and phased design checks to manage risk and refine costs.
Caltrans anticipates using advanced underground construction technologies to improve safety, precision and efficiency while reducing surface disturbance. Technologies could include precision excavation equipment, robotic shotcrete and real-time monitoring.
During the design phase, Caltrans will develop concepts for 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.
Current California Transportation Commission estimates put the construction costs at US$2.5-3.5bn and approximately US$225m for design and right-of-way support. Construction funding has not yet been secured, and Caltrans expects to pursue a mix of federal, state and financing opportunities during design.
Caltrans will also work with local tribes on Native American employment and workforce development, including co-ordination with Yurok Construction Corporation and investigation of training educational opportunities for tribal youth.
“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 travellers deserve.”
