TDIH: The Eisenhower/Johnson Memorial Tunnel Gets Rocky Mountain High

March 15, 1968: Construction starts on the Eisenhower–Edwin C. Johnson Memorial Tunnel, a dual-bore, 4-lane tunnel that carries Interstate 70 under the Continental Divide in the Rocky Mountains.

When the Eisenhower/Johnson tunnel on I-70 just west of Denver was completed, it was, and still is, the highest tunnel in the United States, allowing some 10 million vehicles a year to pass through it. It is also the longest tunnel and highest point on the Interstate Highway System, and was at the time it was completed in 1979, the highest tunnel on Earth.

The complex is actually two different tunnels with slightly different lengths, and were actually one of the last parts of the Interstate Highway System to be completed.

The tunnels original posted height limit was 13 1/2 feet, with any vehicle higher than that triggering an audible alarm that would turn the traffic signals at the entrance red, stopping all traffic through the tunnel. This meant that frequently, trucks that used air suspensions or had a slight accumulation of snow and ice on the trailer would trigger the alarms unnecessarily, and the trucking industry lobby in 2007 successfully argued for the raising of the height limit, bringing it to 13 feet 11 inches.

Construction begins on America’s highest vehicle tunnel

Eisenhower Tunnel