Building the world's greatest rail tunnels

Taking a rail journey invariably means going through a tunnel at some point. Most of the time it's over in a flash, the darkness racing by as quickly as the passing countryside. But have you ever wondered what it takes to build a railway tunnel? Today, modern technology makes it a far easier and safer undertaking. But how did they manage back in the day, when engineering even the shortest tunnel involved a high degree of risk and often cost lives?

Click through, get on track, and enter the world of the railway tunnel.

Gotthard Base Tunnel, Switzerland

The Gotthard Base Tunnel is the world's longest and deepest rail tunnel. The 57-km (35-mi) twin-bore tunnel provides a high-speed rail link under the Swiss Alps, linking Erstfeld with Bodio.

Seikan Tunnel, Japan

At 53 km (32 mi), the Seikan Tunnel in Japan is the second-longest rail tunnel in the world. The dual-gauge tunnel opened on March 13, 1988, having cost US$7 billion (£5.5 billion). 

Channel Tunnel, England-France

The Channel Tunnel, also known as the Eurotunnel, is a 50-km (31-mi) railway tunnel that connects Folkstone in Kent, England, with Coquelles in France. It is the third-longest tunnel of its kind in the world. It was inaugurated on May 6, 1994 and cost US$6.2 billion (£5 billion).

Staple Bend Tunnel, USA

The Staple Bend Tunnel in Pennsylvania was the first railway tunnel constructed in the United States. Completed in June 1833, it was the third tunnel of any kind built in the country. It's pictured abandoned in 1911.

North River Tunnels, USA

An excavation team pictured in 1906 pose with the steam shovel used to excavate the North River Tunnels, a pair of railway tunnels beneath the Hudson River. Built between 1904 and 1908 by the Pennsylvania Railroad to allow its trains to reach Manhattan, the lines linked Weehawken in New Jersey with Pennsylvania Station in New York City and are still operational today.

Simplon Rail Tunnel, Switzerland-Italy

The Simplon Rail Tunnel traversing the Lepontine Alps between Switzerland and Italy consists of two single-track tunnels built nearly 15 years apart. The east tunnel opened in 1906; the west tunnel was inaugurated in 1921. For most of the 20th century this was the longest railway tunnel in the world until the Daishimizu Tunnel in Japan was completed in 1982. The Simplon Rail Tunnel is pictured here in 1956.

Central Pacific Railroad Summit Tunnel, USA

A small army of Chinese immigrants working for the Central Pacific Company in the late 1860s blasted their way through California's Sierra Nevada to build 15 tunnels while completing a transcontinental railway that would unite the nation. The most daunting cavern was the Donner Summit Tunnel (pictured), bored through 505 m (1,659 ft) of solid granite.

St. Paul Pass Tunnel, USA

Opened in 1908, the St. Paul Pass Tunnel went through the Bitterroot Range of the Rocky Mountains on the Montana-Idaho border. One of the so-called Milwaukee Road tunnels set along its Pacific Coast Extension, the St. Paul Pass, nearly 1.6 km (1 mi) in elevation and roughly the same in length, ceased to be used in 1980. Today it serves as a rail trail route for hikers and bicyclists, the Route of the Hiawatha Trail.

Moffat Tunnel, USA

Named after Colorado industrialist and railroad pioneer David Moffat (1839–1911), the Moffat Tunnel cuts through the Continental Divide in the north-central region of the state. Opened in 1928, it also serves as a water tunnel, delivering a portion of Denver's water supply. The tunnel is pictured in 1978, a year before it was was designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.

Hoosac Tunnel, USA

Work began on the Hoosac Tunnel in Massachusetts in 1851 to pass through the Hoosac Mountain range and connect the town of Florida with the city of North Adams. After its completion in 1875, Hoosac was the world's second-longest tunnel after the Mont Cenis Tunnel through the French Alps. It's still active today.

Summit Tunnel, England

Constructed between 1838 and 1841 by the Manchester and Leeds Railway, Summit Tunnel in England is one of the world's oldest railway tunnels. It was bored beneath the Pennine Hills to provide a direct line between Leeds and Manchester and was once the longest rail tunnel on the planet. It has remained in continuous use since 1841.

Connaught Tunnel, Canada

The Connaught Tunnel in southeastern British Columbia carries the Canadian Pacific Railway main line under Mount Macdonald in the Selkirk Mountains. Opened in 1916, the Connaught Tunnel is one of two tunnels set under Rogers Pass, the other being the Mount Macdonald Tunnel.

Zugspitz Tunnel, Germany

Pictured: railroad workers in 1929 boring the tunnel through the Zugspitz, at 2,962 m (9,718 ft) the highest mountain in Germany. They were advancing the line from Garmisch to the Zugspitzplatt, approximately 300 m (984 ft) below Zugspitze. The Bavarian Zugspitze Railway is one of four rack railways still working in Germany, along with the Wendelstein Railway, the Drachenfels Railway, and the Stuttgart Rack Railway.

Spiral Tunnels, Canada

The Spiral Tunnels were built in 1909 as a means of overcoming the "Big Hill" on the Canadian Pacific main line in British Columbia. The most difficult piece of railway track on the route due to its steep elevation, the Big Hill posed a dangerous challenge to passenger and rolling stock. The two Spiral Tunnels lessened the gradient by effectively lengthening the track.