I-70's Eisenhower/Johnson
Memorial Tunnel

Milestones
September/October 1999

A Look Back

Twenty years after the four lane began, the second bore of the Eisenhower/Johnson Memorial Tunnel complex approaches its 20th birthday this December.  Some 26,362 vehicles roll through the Continental Divide on any given day, and on peak summer weekends the figure is about 47,000 just during a Sunday.   For all the "new campers" in Colorado, and for the generation of drivers born after the blasting and smoke cleared, here is a question and answer review

Trivial Pursuit? 

Not to the more than 50 dedicated employees who keep the complex operating 24 hours a day...fan maintenance, snow plowing, water and electrical, maintenance, round the clock television surveillance...employees who keep the 1.7 miles among the safest on America's highways or Interstate.

By the way, each tunnel has 2,000 light fixtures with 8-ft. bulbs in each fixture.

Why is the complex named after a couple of presidents?

Just one president.  The first bore was dedicated to the memory of President Dwight D. Eisenhower, "father of the Interstate Highway System" who as a young second lieutenant in a 1919 cross-country Army convoy saw the need for a wide, interconnecting system which he later (signing the Federal-Aid Highway Act of 1956) launched as the National System of Interstate and Defense Highways.   We view the wide, well-shouldered routes as good routes for cross country trucks and automobiles.  Eisenhower saw a design which would carry tanks, troops and heavy military equipment during wartime.

The first bore carried one lane of traffic in each direction.  Democrats won the name game when the second bore was opened.  The twin tunnel was dedicated to Edwin C. Johnson, 1884-1970, who served as a state legislature, lieutenant governor, and governor and as a U.S. Senator and had fought successfully for and Interstate route across Colorado.

Pilot bore engineers know the complex as the Straight Creek Tunnel, for the creek on the west side of the continental Divide which runs toward Dillon Reservoir.  (On the east side, Clear Creek begins its run eastward toward Georgetown and Denver.)

When were the twin tunnels built?

A pilot bore for Straight Creek Tunnel was finished in 1964, to see what kind of geology miners would face to support a hole some 50 feet high and 45 feet wide.

In 1968 mining began for the first bore, dedicated and opened to two way traffic March 8, 1973.  Work on the second (eastbound) bore began in 1976; the complex went to four lanes December 23, 1979.

Plans for a tunnel under the Continental Divide date back to 1867, when W.A. Loveland had a railroad charter under the Territorial Legislature.   Building a railroad tunnel turned out to be too large a task for early engineers and technology, so Loveland opted to build over the top.  His railroad never made it past Silver Plume, but he did build a wagon road which later became the highway over Loveland Pass.

The idea of tunneling was resurrected in the early 1940s.   But it was not until the 1960s that suitable technology and funding existed to make tunnel construction a reality.

What were the costs back then?

For the Eisenhower Tunnel, $116.9 million.   For the Edwin C. Johnson Bore, $144.9 million.

What do I, the driver, save by using the tunnels instead of Loveland Pass?

By going through the tunnel, each driver saves about $4 compared with driving U.S. 6 over Loveland Pass...along with saving 9-1/2 miles distance and about half an hour's time.

The elevation going over U.S. 6, Loveland Pass, reached 11,992 feet.   What about through the tunnel complex?

There's a slight uphill incline from the eastern portal, at 11,012 feet, to the west side at 11,158 feet elevation above sea level.   The Eisenhower/Johnson Memorial Tunnel complex is the highest vehicular tunnel in the world.

How does CDOT keep the air so clear inside?

Large ventilation fans (with blades 10-1/2 feet across) at each end of the tunnel complex assure that carbon monoxide levels stay at a low level --- usually in the range of 15 to 20 parts per million.  The Department of Public Health requires that levels of carbon monoxide not exceed 100 PPM for extended lengths of time.  The westbound Eisenhower tunnel has 16 fans; for eastbound (Johnson bore), on a slight downhill grade, there are 12.

Got any ghost stories?

How about superstition?  About men thinking women working underground was bad luck?

The first woman ever to be employed on a tunnel project was Janet Bonnema of Georgetown, hired as an underground technician when officials misread her name ("James") and thought she was a man.  When she showed up for work November 9, 1972, sixty miners walked off the job.  Bonnema was immediately assigned to an office job.

She sued the state and won the right to work underground on the tunnel project.

Are there television cameras inside, watching me?

Not just inside, but on both approaches.   In full color.  Workers watch for oversize trucks, for example, or haulers of hazardous materials (who stop and wait to proceed in convoy, at the top of the hour, when U.S. 6 is closed).  Let's say a truck runs past the warning red light and siren: the truck description and license number is radioed to Colorado State Patrol, so the driver gets a ticket down the road.

The tunnel control room has thirty 18" color TV screens and eight 32" monitors whose cameras can tilt, zoom, and pan left-right.  Safety crews can quickly react when a vehicle stalls, catches on fire, or otherwise needs help in a hurry.

There has not been a baby born inside the tunnels but over the years numerous events have required the highly trained employees to provide emergency medical care, stop vehicle fires (one had ammunition popping while the crew doused the fire), and tow/haul disabled vehicles out of harm's way.

Okay, what if the lights go out?

Two 24,900-volt power lines serve the complex, one coming in from each side of the mountain.  If a partial outage occurs, a single line can serve both side until power is restored.  If a total outage were to happen, an emergency generator would start, to keep the tunnel operating.

You're going to ask next about the cost.  The electricity bill for the tunnel is budget at about a million dollars a year.  (Tunnel management people are presently working with a consultant to identify any potential cost saving to this large utility expenditure.)

When did CDOT start the crossover plan running three lanes eastbound and one westbound on Sunday afternoons?

About ten years ago, traffic volumes built to a point where more weekend capacity was needed eastbound.  The westbound tunnel is coned for one lane each direction, just as it served in its initial 6-1/2 years.  But tunnel engineers try to avoid the switch unless absolutely necessary.

I-70 is getting SO congested.  Why can't CDOT dig those tunnels wider for six lanes?

The rectangle shape you drive through is just the bottom 1/3 of a horseshoe shape.  Your suspended ceiling is 16 feet, four inches high but the excavation is 48 feet high. There are air ducts above, and drainage provided below the rectangle you drive through.

The oval shape is reinforced with steel sets rock-bolted into the mountain.  Top, bottom, and sides...the tunnels are encased against geologic pressures, faults and shear zones under the Continental Divide.  Steel sets were then concrete lined.  No, you don't just "dig wider" after building this way inside a mountain that vexed engineer with its weak rock and shifting load pressures.

It took twelve years construction time to achieve the tunnels we have today.