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Sep 30, 2007 5:41 pm US/Mountain
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Eisenhower Tunnel May Be Widened In Future
Written by Andrea Lopez
by Andrea Lopez
(CBS4)
As the Colorado Department of Transportation explores alternatives or ideas for the future of Interstate 70, widening I-70 and some type of rail system are two options that seem to be generating quite a bit of attention.
Although it may be some time before one, or a combination of the both are chosen, they are both likely solutions for the future. But both of those options would require an additional bore at the Continental Divide where the Eisenhower and Johnson Tunnels currently sit.
The tunnels are located about 60 miles west of Denver on I-70. The Eisenhower Tunnel is the highest auto tunnel in the world. The East Portal sits at an elevation of 11, 013 feet and the West Portal is at 11,158. Construction started on the first tunnel or the westbound bore on March 15, 1968. It wasn't until Decemer 21, 1979 that the entire project was finished and at a cost of $262 million. The average snowfall there at the Continental Divide is about 26 feet a season, and the tunnels divide Clear Creek County from Summit County. At the time, they were the most difficult tunnels in the world to build.
"There were tremendous challenges with trying to build it because there's a fault that goes right through the mountain that they ran into when they were constructing the tunnel," said CDOT Program Engineer Brian Pinkerton. "It shut down construction for over a year. What the fault did is it caused the rock to squeeze around the tunnel that they were boring and it actually squeezed some of the equipment they were using for boring to the point where they couldn't even get it back out. They tried to figure out how to deal with this and came up with a system of tubes that they would excavate around the tunnel, filling those with concrete -- that allowed them to proceed through the fault and ultimately build the tunnel. It was the first time in history that this had been done where they put in these little tubes around what would ultimately be the tunnel, and that actually allowed them to excavate in-between the tubes to pull that material out and build the tunnel."
Constructing a third bore today would be equally as challenging, and may still be the most difficult tunnel in the world to build because of those issues. But it would be likely if either I-70 is widening or if a rail system is built.
"Any expansion of the corridor-there would have to be a third tube," said Pinkerton. "So if we were to widen the highway or build a high speed train up to this point, you're looking at a third tube to the north of the existing tunnels."
If I-70 is widened for four to six lanes in Clear Creek County, traffic would hit a pinch point at the tunnels which are currently two lanes in each direction. Once traffic gets through the tunnels, I-70 again spans into six lanes or three in each direction. CDOT would want I-70 to be a seamless six lanes into the high country. Hence, it would build a third bore.
If, for example, a monorail is built, it would have to have its own bore or new tunnel at the divide. Pinkerton said some people have suggested that a monorail could just go over the divide, but he said it would be too difficult to build the guideway with the grades up there. The land is also national forest service land, and the red tape involved with trying to build a train over the divide would make things extremely difficult if not impossible.
If a combination of widening and a rail system is chosen as the preferred alternative, one tunnel may accommodate both the monorail as well as three westbound lanes.
"If we're looking at highway improvements, the new tunnel, we would want it to have three lanes going westbound," said Pinkerton. "If it's a transit tunnel then we would have two way train traffic in it. If it's some combination of both there are a lot of questions about that because technically, it's not known whether you could build a tunnel big enough to handle both additional lanes of traffic and a train."
This is how a new tunnel would function. It would be built to the north of the existing tunnels, and it would likely be longer than the current 1.69 mile stretch. That new tunnel would handle all westbound traffic with three lanes. The existing tunnels would then handle the eastbound traffic. One tunnel would have two lanes of eastbound traffic, and the other would have just one lane.
"Now a third tunnel would go to the north and have to be longer and have to go through more length of landslide-there's a landslide on the east side of the Eisenhower Tunnel here," said Pinkerton. "It would once again have to go through this fault in the middle of the mountain and probably be bigger in diameter than the two tubes that are here to accommodate the needs. A third tunnel would be extremely difficult to construct, although possible."
The Eisenhower and Johnson Tunnels hold one of the most expensive stretches of interstate in the nation to maintain -- if not the most expensive stretch. They're staffed 24/7, and there are more than 100 cameras to monitor every inch of the tunnels at all times. The electricity bill alone is $800,000 a year. The cost to replace the white, tile panels in just one of the tunnels will cost $10 to $12 million. A third bore would increase the yearly expenses for CDOT at the divide, after it found a way to fund the initial construction costs.
"We are looking at, just for the tunnel itself, at least a half billion dollars," said Pinkerton, "and when you build the approaches…you're probably talking over $1 billion total."
If I-70 is widened in Clear Creek County, Pinkerton said they would likely build the tunnel first. The excavated material like dirt and rock could be used as a base or fill material, aiding in the construction of additional lanes. The construction details are sketchy at this point in time. A plan has to be identified for I-70 first. Only then will CDOT start examining the details of building a third bore, planning exactly how it should be done.
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