The Simplon Tunnel

February 24, 1905 - It was on this day that two work crews converged deep under the Swiss Alps to form one of the greatest engineering feats of all time, the Simplon Railway Tunnel.

Construction began in 1898. Each day as many as 3,000 workers toiled in the sweltering tunnels that were drilled from opposite ends of the proposed path through the mountains. One entrance was in Italy and the other was in Switzerland.

During the 12.5 miles of drilling and blasting, work crews encountered all kinds of problems, like a subterranean river and temperatures as high as 131 degrees Fahrenheit. For long periods of the operation, the miners had to stand knee-deep in pools of scalding hot water.

On the day the two tunnels were connected, a heavy explosive charge blasted away the last wall of rock. This unleashed a torrent of hot water that killed two sightseers who had come to see the junction. Over the 8 years of construction, 67 men were killed in accidents and many others died from related illnesses.

For over 80 years this would be the longest tunnel in the world. Today, the Gotthard Base Tunnel in Switzerland is the longest at 35 miles through solid rock.