Located on the boundary of Summit and Clear Creek counties, in the U.S. state of Colorado, the famous Eisenhower–Edwin C. Johnson Memorial Tunnel is one of the highest vehicular tunnels in the world, at 3.401m (11,158ft) above the sea level.
Set high in the Rocky Mountains of Colorado, within the Arapaho National Forest, the tunnel carries the paved Interstate 70. The tunnel was originally going to be called the Straight Creek Tunnel. The approach grades are steep, being 7 percent on the west approach and 6 percent on the east approach. Weekends and holidays have the highest traffic volumen. Building the tunnels through the Continental Divide was tough. Seven workers died during construction, and many dozens suffered amputations or other life-changing injuries. The air quality is monitored 24 hours a day, seven days a week in a control room by two to three tunnel employees at all times.
Some 10 million vehicles drive through the tunnel each year. The westbound tunnel is called Eisenhower Memorial Bore. It’s 1.693 mi (2.72 km) long. Its construction started March 15, 1958 and was completed in March 8, 1973. The eastbound tunnel is called Edwin C. Johnson Bore. It’s 1.697 mi (2.73 km) long. Its construction started August 18, 1975 and was completed in December 21, 1979. Hazardous material vehicles are not allowed through the tunnel unless Loveland Pass is closed. Traveling through the tunnels the public saves 9.1 miles by not having to travel over U.S. Highway 6, Loveland Pass.
The Eisenhower–Edwin C. Johnson Memorial Tunnel is NOT the highest vehicular tunnel in the world as some websites state. Check here the list of the highest tunnels in the world.