In the U.S., after 30 years of speculation, legal wrangles and other delays, California has been given US$150.3M towards the building of two 1.2km long tunnels to bypass the Devil’s Slide section of its coastal Highway 1.

Reports said the announcement of the financial assistance for the US$230M tunnel between Pacifica and Montara was welcomed by both residents and environmentalists. The highway has been plagued my mudslides after heavy rain ever since it opened, which often led to it being closed for considerable portions of time while clean-up operations got underway.

In January 1995, a major rock slide led to the road being closed for 150 days. Caltrans, the California Department of Transportation, carried out a US$1.5M project to repair and stabilise the road by installing grouted rockbolts that were post-tensioned. Mesh was also installed to catch minor spalling.

The road has remained largely unaffected since then, but Caltrans has always maintained that the measures undertaken were only temporary and a tunnel to the east of Devil’s Slide is the best permanent solution.

Caltrans is hoping to break ground on the five year project in early May. Two 9.14m diameter tunnels will be driven, one for each direction of traffic flow. Each bore will accomodate a single lane with two 2.4m wide shoulders. Caltrans had initially favoured an inland bypass, but environmental lobbying against their proposal changed their stance to advocate the tunnels.

The project will be financed largely by federal emergency funds with less than one percent of the funds coming from the State Transportation Improvement Program. This designation of emergency repairs saves the tunnels from having to compete with other California transportation projects for state funds.