Swiss mark opening of world's longest and deepest rail tunnel

GENEVA — Switzerland will celebrate an engineering marvel 20 years in the works on Wednesday: the debut of the world's longest and deepest railroad tunnel.

The new tunnel through the Alps is 35.5 miles long, exceeding by 2 miles the current record-holder, Japan’s Seikan Tunnel. Some sections lie a record 1.4 miles beneath the mountain's peak.

The tunnel will carry 325 passenger and freight trains a day, with each trip taking 20 minutes at speeds up to 150 mph. The goal is to reduce heavy auto traffic that creates pollution.

“We are not showing off,” Transport Minister Doris Leuthard told Swiss Radio International about the $8 million grand opening expected to draw 100,000 people. That's a modest sum to spend to showcase a mammoth project that cost $10 billion and employed thousands of  workers.

The tunnel will go through 7,000-foot Gotthard Mountain. The mountain pass has long served as Europe's main north-south axis through the Alps, handling 6 million vehicles a year.

Trucks hauling cargo across the continent’s most densely populated area, stretching from the United Kingdom to Italy, inevitably pass through the Gotthard, often creating congestion.

To reduce the environmental impact of cars, the Swiss have wanted to shift traffic from the road to rail. In a 1992 referendum, voters approved constructing a tunnel to reduce transit time, hauling costs and air pollution.

Work started in 1996, and the actual excavation using giant rolling drills 1,345 feet long and weighing 300 tons was completed in 2010. A 1,970-foot-long machine laid the concrete lining and drainage pipes. And once 28 million tons of rock were removed, workers began to install the tracks in two tunnel tubes.

The lengthy time to complete the project was not unusual given its complexity, said Kalman Kovari, emeritus professor of tunneling at the Federal Institute of Technology in Zurich and a consultant on the project.

The geology of the Alps means the hardness of the rocks vary, and “the rate of excavation per day depends on rock quality,” Kovari told USA TODAY. Even with high-performance boring machines, “it was clear that the construction time could not have been reduced substantially,” he added.

Engineers knew from the beginning that tunneling through the mountain would not be easy or quick. They’d have to excavate through some hazardous zones that had crumbling rocks or potential flooding.

The engineers solved the problem by using steel arches to support the excavation, a mining technology used for the first time in an underground tunnel.

Other potential problems had to be tackled before construction could begin. One was that temperatures at the deepest spots exceeded 100 degrees. So the air had to be cooled to protect 2,600 workers excavating the rock.

“It was also important to protect the workers from accidents,” Kovari said. “Strategies had to be developed to recognize the nature of the rock and to apply the highest industrial mechanization during excavation.”

Passenger safety also was a priority. According to AlpTransit, the company in charge of the project, a series of sophisticated emergency evacuation sites and alarms are installed along the train route.

The Swiss, known for carefully crafted watches, chocolates and army knives, are just as proud of this gargantuan achievement. As the government boasts on its website, the tunnel “symbolizes Swiss values such as innovation, precision and reliability.”