Colorado DOT Celebrates 50th Birthday of Eisenhower Tunnel

The 1.7-mile long I-70 Eisenhower Tunnel – the highest point on the nation’s interstate system at 11,200 feet – turned 50 years old in March 2023.

[Above photo by the Colorado DOT]

The Colorado Department of Transportation celebrated that historic milestone by with a special news event that included a parade of 1970-vintage vehicles – including a fire truck, state patrol vehicle, and sports car – traveling through the tunnel.

Photo by Colorado DOT

Located about 60 miles west of Denver and under the Continental Divide, over 434 million vehicles have traveled through the Eisenhower Tunnel and its twin – the Johnson Tunnel – since it opened on March 8, 1973.

The Eisenhower Tunnel originally handled both east and westbound traffic. Following the completion of the Johnson Tunnel in 1979, eastbound traffic shifted to its own dedicated two-lane tunnel.

“While motorists drive through the tunnel in a few minutes, they may not realize the monumental effort it took to plan and build such an infrastructure under the most challenging of circumstances,” said Colorado DOT Executive Director Shoshana Lew in a statement.

Shoshana Lew. Photo by Colorado DOT.

“Over a five year construction period, 6,000 people and heavy machinery worked a total of 4.9 million hours to bore through granite under the Continental Divide in harsh weather conditions,” she pointed out.

“When construction started in 1968, it was the largest single federal-aid highway project in the nation’s history. [Since then] it has provided a critical life-saving link for moving goods and services [in] Colorado,” Lew added.

Prior to the construction of those highway tunnels, the east-west mountain routes in Colorado traveled US 6 over Loveland Pass and US 40 over Berthoud Pass, Colorado DOT noted – mountain passes that often proved treacherous during the winter, greatly limiting travel.

Photo by Colorado DOT

The tunnels – which took five years to build at a cost of $110 million – are today served by a dedicated crew of more than 30 full-time employees who monitor around-the-clock television surveillance of the tunnels, provide emergency response, tunnel washing, ventilation maintenance, tunnel sweeping, snow removal, heavy equipment servicing and repair, and water treatment.

The tunnel crew also serves as firefighters, using dedicated fire trucks and firefighting equipment so they can respond immediately to incidents. That capability is complemented by a new tunnel fire suppression system added in 2015.

Currently an average of 35,000 vehicles a day travel the tunnel, with the highest volumes of over 50,000 a day typically in July and August.

Colorado DOT added that is modernizing much of the tunnel’s internal operations systems – electrical, water treatment plant and other functions – and continues to upgrade outdated and aging parts of the structures as part of the agency’s 10-year transportation plan.

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