FORT BRAGG — Train tunnel Number One on the old California Western Railroad has endured a lot of punishment since it was hacked out of the serpentine and metasandstone rock east of Fort Bragg by Chinese and Italian laborers a century ago.
It has endured earthquakes, landslides that blocked the tunnel openings, most recently in 1997 and 2006, broken timbers and even an oversized boxcar that got wedged inside and had to be cut up and removed piece-by-piece in the 1970s.
But now it is facing a threat that could shutter the 128-year-old rail line and Mendocino County's beloved tourist attraction, the Skunk Train.
Sometime overnight between April 12 and 13, a 40-foot length of the tunnel collapsed for reasons still unexplained, dumping thousands of tons of rock onto the track, rubble that Skunk Train officials say they cannot afford to remove.
"What happened, I don't know; even the geotechnical engineers don't know," said Mendocino Railway Vice President Robert Pinoli. "Was there a shift in the mountain? Was it a small earthquake?"
The train, now run by Mendocino Railway, is launching a campaign to raise the estimated $300,000 it will take to remove the largest blocks of rock sitting on the rails, offering special "Save Our Skunk" passes and opening a fundraising campaign through the website Kickstarter.
Unless that tunnel is reopened, Pinoli said, the future of the railroad is bleak.
The 40-mile historic railroad connects Fort Bragg and Willits, winding along the redwood-lined Noyo River and passing through two mountain tunnels. The collapse came in the tunnel just three miles outside Fort Bragg.
"We can do tunnel repairs, but this is far larger than anything we have ever encountered before," Pinoli said.
The scale of the collapse is difficult to describe. The neat 13-by-16-foot tunnel, lined with huge redwood beams bracing walls of 3-inch-thick redwood planks, now suddenly ends about 300 feet from the eastern end at a tangled pile of boulders and rubble. At the center is a huge, square chunk of rock, at least 15 feet across.
"We've pulled out some big pieces, broken them up" during the preliminary cleanup, Pinoli said, nodding toward the huge boulder, "but this is a monster."
The best estimate is that once the rocks are hauled away, the cave-in will leave a cavern more than 50 feet wide, 40 feet long, and 30 feet high. That's about the size of the Skunk Train's headquarters building in Fort Bragg.
Inspectors had noticed some bulging in a retaining wall in the 1,122-foot-long tunnel two days before the collapse, indicating a problem, but they didn't expect a massive collapse before repair crews could shore it up. Such bulges occur once every few years, Pinoli said, and they usually indicate just a small shift in the rocks behind the redwood planking that is easily cleaned out and shored up.
After the collapse, railroad crews did their best to remove the rubble, Pinoli said, but after hauling out at least six dump-truck loads of rock, they concluded the scale of the damage was so great, they would need outside help.
Bids are coming in, he said, but it appears the remaining work will cost more than $300,000 and require several weeks.
The privately run company won't release its financial information, but Pinoli said its reserves are drained after suffering a series of expensive blows in recent years. Heavy rains in 2006 caused mudslides that cost a great deal to clear, he said. A 2011 manhunt for an armed killer hiding in the woods along the tracks dragged on for more than a month and cost the company $200,000, none of which has been reimbursed by the law enforcement agencies that used the tracks and trains for the search.