Officially known as the Eisenhower–Johnson Memorial Tunnel, the Eisenhower Tunnel is situated in Region 1 of the Colorado Department of Transportation, in Maintenance Section 9. Lying entirely in the Arapaho National Forest, the facility is separated by Summit County and Clear Creek County at the West and East portals respectively. This four-lane and dual-bore vehicular tunnel makes the transport of goods and people from the Rocky Mountains’ Eastern Slope to the Western Slope easier. It is one of the nine Maintenance and Operations Section committed at maintaining the best transportation system for the state.
Currently, the Eisenhower Tunnel is the highest vehicular tunnel in the US and one of the world’s highest, with an elevation of 3,401 m above sea level. It is also the longest mountain tunnel as well as the highest point on the Interstate Freeway System. Construction of the tunnel was completed in 1979, which made it one of the last main parts of the Interstate to be completed.
Named after former president Dwight D. Eisenhower, the westbound bore stretches 1.693 mi, while the eastbound bore, named after former US senator Edwin C. Johnson, is 1.697 mi long.
While the tunnel bores measure 12 m by 15 m, the part that can be accessed by the public measures only 4.9 m, with the rest of the bore used for water drainage systems and forced air ventilation.
Through a retrofit utilizing lower profile lighting and signs, trucks with a height of 13.92 ft can already enter the Eisenhower Tunnel, an increase of five inches from the initial 13.5 ft. Once vehicles above the posted height try to go into the tunnel, audible sirens located near every entrance are activated, and all traffic signal at the said entrance turn red to stop all traffic. The entrance remains close unless the over-height truck is taken away from the freeway.
In order to alleviate the dangers posed by fire in the tunnel, vehicles hauling dangerous materials are barred from entering the tunnel. Prohibited pedestrians, bicycles, trucks and those who want to see the scenery can take the steeper and longer climb and descent of the US Highway 6 located across Loveland Pass, which is 254 m higher than the Eisenhower Tunnel. The approach to the Eisenhower Tunnel on both sides is steep, with runaway truck ramps available for truckers losing control.
Eisenhower Tunnel is manned 24/7 to provide an adequate and safe level of service to the public.