As part of this week's feature, "Rocky Mountain High," we went inside the control room of the Eisenhower Tunnel, the world's highest vehicular tunnel, which famously crosses the Continental Divide. More than 300 million cars have passed through since 1973, and the rate today is twice what is was thirty years ago. But detailed traffic counts show that in recent years, there has actually been a slight decline in cars.
The 1.7-mile tunnel on I-70 -- located sixty miles west of Denver at 11,155 feet above sea level -- saw a record high of 11,735,362 vehicles in 2009. That number dropped to 11,391,704 in 2010 and to 10,760,470 in 2011. The total from last year is actually lower than the total in 2005 (see counts for the past ten years below).
"We started wondering about it," says John Wilson, a tunnel supervisor for sixteen years. "Our biggest months are in the summer and those have been lower a little bit."
The Colorado Department of Transportation's first guess was that fewer people were skiing or vacationing in the mountains because of the recession. But when traffic counts continued to decline even as the economy recovered slightly, their answer became more complicated.
"The resorts are still getting good bookings, but the number of cars is going down," Wilson says. "That indicates carpooling."
Mike Salamon, a superintendent at the tunnel, adds, "Prior...it was just a steady increase of about 3 percent. I think [it's] due to fuel costs and the economy, and I think we're seeing in the wintertime a little bit more carpooling."
While the numbers have dropped a bit, that doesn't make the job maintaining the tunnel and monitoring thirty large screens any easier for the fifty employees who rotate through on a 24/7 basis. The tunnel and the one-acre attached control room are cut off from emergency services in either direction. That means the tunnel must be self-sufficient in many respects. It has its own water treatment facility and fire emergency equipment.
"We still have the same challenges," Wilson says.
Page down to see more photos from inside the control room and more traffic count data. Total annual traffic counts from the last two decades, courtesy of the Eisenhower Tunnel:
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1990 -- 6,900,963
1991 -- 7,279,287
1992 -- 7,643,696
1993 -- 7,882,333
1994 -- 8,315,443
1995 -- 8,480,253
1996 -- 8,883,930
1997 -- 9,186,153
1998 -- 9,586,857
1999 -- 9,876,677
2000 -- 10,296,755
2001 -- 10,614,957
2002 -- 10,872,341
2003 -- 10,617,377
2004 -- 10,692,957
2005 -- 10,812,205
2006 -- 11,092,693
2008 -- 11,550,601
2009 -- 11,735,362
2010 -- 11,391,704
2011 -- 10,760,470
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Page down to see more photos behind the scenes at the Eisenhower Tunnel. Page down to see more photos behind the scenes at the Eisenhower Tunnel.
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