TRANSPORT officials in California are planning to build an 11-mile tunnel through a mountain range in earthquake country to ease gridlocked traffic between Orange County and the desert suburbs.

The tunnel, a feat of modern engineering, would be the second largest of its kind in the world, take about 25 years to build and cost $9 billion (£5.2 billion). The British company Halcrow is advising on the project, and has told officials that the tunnel is “viable and feasible”.

But opponents say that it is madness to construct an underground motorway barely a mile from a fault that has produced a 6.0-magnitude earthquake. They have nicknamed the project the “terrible tunnel”. Cathryn DeYoung, the Mayor of Laguna Niguel in Orange County, said: “It’s absolutely absurd to have a tunnel 700ft below ground in earthquake country. I mean, would you want to be in that tunnel?” Everyone agrees on one thing, however: something must be done to reduce the gridlock from Orange County, one of the fastest growing areas of California, to housing developments further inland.

Planners have spent 18 months and $15 million studying the issue and officials are expected to choose between three options — two of them involving a tunnel — before the end of this week.

One popular alternative, a “double-decker” motorway, has also been criticised as too risky because of seismic activity.

Forty-thousand people now commute into Orange County daily from the surrounding areas, including Los Angeles. Almost everyone drives. The largest number come from Riverside County, which sends 52,000 cars per day to Orange County, but the two counties are separated by the 25-mile long Santa Ana Mountains.

The only significant road between them, State Highway 91, carries 268,000 cars per day, about 50,000 more than it was built to handle. Officials have estimated that, in another 25 years, the road will be carrying 500,000 cars.

One Highway 91 commuter is Howard Gottesman, a 44-year-old property manager, who says that he can spend 90 minutes travelling the six miles from his job in Orange County to his home in Corona, just inside Riverside County.

“I call it the longest six miles in the world. It’s wear and tear on the car and it’s wear and tear on me,” he said. “They need to do something, whether it’s double-decking the freeway or tunnelling under the mountains. We need relief.”

The tunnel would rank second in length to Norway’s 15-mile Laerdal Tunnel, which opened in 2000, Michael Litschi, a spokesman for the Orange County Transportation Authority, said. But the California tunnel would handle far more traffic than its Norwegian counterpart, which averages 1,000 cars per day.

“A tunnel is actually a very safe place,” Mr Litschi said. “We don’t want to run it through the faults and we’re going to avoid that. If they can do it in Europe, then we can do it here.”

Others say that the tunnel is doomed from the beginning, because what California really needs is more commuter trains. “Every study shows that you can’t build your way out of congestion,” Karl Warkomski, the mayor of Aliso Viejo, in Orange County, said. “Eventually, you’re going to get a point where you’re back to square one — where we are now, or even worse.”

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