Eisenhower Tunnel
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The Eisenhower Tunnel, officially the Eisenhower–Edwin C. Johnson Memorial Tunnel,<ref name=ejmt/> is a dual-bore, four-lane vehicular tunnel in the western United States, approximately Template:Convert west of Denver, Colorado. The tunnel carries Interstate 70 (I-70) under the Continental Divide in the Rocky Mountains. With a maximum elevation of Template:Convert above sea level, it is one of the highest vehicular tunnels in the world. The tunnel is the longest mountain tunnel and highest point on the Interstate Highway System. Opened in 1973, the westbound bore is named after Dwight D. Eisenhower, the U.S. President for whom the Interstate system is also named. The eastbound bore was completed in 1979 and is named for Edwin C. Johnson, a Colorado governor and U.S. Senator who lobbied for an Interstate Highway to be built across Colorado.
DescriptionEdit
The Eisenhower Memorial Bore (westbound tunnel) is Template:Convert long, while the Edwin C. Johnson Memorial Bore (eastbound tunnel) is Template:Convert long. The tunnels are sloped with a 1.64% grade, with an elevation of Template:Convert at the east portal and Template:Convert at the west portal.
At its dedication, the Eisenhower Tunnel was the highest vehicular tunnel in the world.<ref name=ejmt>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> While it remains the highest vehicular tunnel in the US, and longest mountain tunnel and highest point on the Interstate Highway System, higher tunnels have since been constructed elsewhere, such as the Fenghuoshan Tunnel, a rail tunnel in China.<ref name=rts>Template:Cite magazine</ref><ref name=highwaystothesky/>
The tunnel bores measure Template:Convert. The traveled portion is a rectangular shape just over Template:Convert tall. The space above is used for forced air ventilation while the space below the roadway is used for drainage.<ref name=ejmt/>
Template:As of, more than 434 million vehicles had passed through the tunnel. This figure includes a significant number of visitors to Colorado's ski resorts.<ref>Template:Cite press release</ref>
Height restrictionEdit
Due to additional height restrictions from variable-message signs and lighting systems, the original posted clearance of the tunnels was Template:Convert.<ref name=ejmt/> The trucking industry lobbied the Colorado Department of Transportation (CDOT) to increase the vertical clearance. In 2007, the tunnel was retrofitted with lower-profile lighting and signs, increasing its clearance by Template:Convert to Template:Convert.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
A height detector near each tunnel entrance sounds a siren and turns traffic signals red, stopping all traffic, if an overheight vehicle attempts to enter the tunnel. The entrance will remain closed until the vehicle is removed from the freeway, which can cause severe delays. CDOT noted that prior to the retrofit, about 20,000 vehicles per year tripped the alarm. The trucking industry argued that many of these trucks were under the height requirement but tripped the alarm due to their air suspensions (which can be lowered during their journey through the tunnel) or due to snow and ice atop the trailer. During this time, the trucking industry estimated the number of alarms would drop by as much as 80% if the clearance could be raised even a few inches.<ref name="rmn1">Template:Cite news</ref>
The 2007 retrofit also added a weigh-in-motion system that calculates a safe speed for trucks on the 7% grades and curves on the departures from the tunnels and displays it to each driver.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Alternate routeEdit
While the tunnel has largely supplanted the older route of U.S. Highway 6 over Loveland Pass, hazardous material carriers (hazmats), bicycles, and pedestrians are prohibited from the tunnel and must use the pass, which is longer, steeper, and Template:Convert higher at Template:Convert. And while the tunnel's route is less formidable than the pass, its approaches are steep nonetheless and have runaway truck ramps.<ref>Template:Cite news</ref>
If Loveland Pass is closed—such as for construction or storms—the hazmat prohibition is temporarily lifted and the tunnel is closed to regular traffic once per hour to allow hazmats to be escorted through the tunnel in a convoy.<ref>Template:Cite news</ref>
HistoryEdit
The idea for a tunnel under Loveland Pass existed since at least the 1950s.<ref name=lticws>Template:Cite news</ref> William A.H. Loveland had an idea of a tunnel under the divide in 1867, but instead got the wagon road now known as Loveland Pass built.<ref name="gjds_pt1">Template:Cite news</ref> Serious discussion began when the state of Colorado lobbied for the Interstate Highway System to route a transcontinental highway across Colorado. After a round of negotiations with Utah officials, it was decided the best option was to follow the US Route 6 corridor. Engineers recommended tunneling under the pass, rather than attempt to build a route across conforming to Interstate Highway standards.<ref name=rambler/>
The Eisenhower–Johnson Memorial Tunnel was known as the Straight Creek Tunnel during construction,<ref name=stcrtnp>Template:Cite news</ref> named for the waterway that runs along the western approach to the tunnel. Before the tunnel was dedicated, it was renamed to honor Dwight D. Eisenhower and Edwin C. Johnson. The original Pioneer bore to access the two larger bores was "holed through" in late 1964, after fourteen months.<ref name=tunhtir>Template:Cite news</ref> Construction on the first bore of the tunnel was started on March 15, 1968.<ref name=ejmt/> Construction efforts suffered many setbacks and the project went well over time and budget.<ref name=stcrtnp/> One of the biggest setbacks was the discovery of fault lines in the path of the tunnel that were not discovered during the pilot bores.<ref name=Cdoteisenhower2/> The first construction contractor went bankrupt excavating rock in this fault zone.<ref>Template:Cite news</ref> These faults began to slip during construction and emergency measures had to be taken to protect the tunnels and workers from cave-ins and collapses.<ref name=highwaystothesky>Template:Cite book</ref> Despite the best efforts of engineers, three workers were killed boring the first tube and four in boring the second.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Further complicating construction, the boring machines could not work as fast as expected at such high elevations and so the productivity was significantly less than planned. The frustration prompted one engineer to comment, "We were going by the book, but the damned mountain couldn't read."<ref name=Cdoteisenhower2/> Though the project was supposed to take three years, the tunnel was not opened to traffic until a March 8, 1973, dedication ceremony by Governor John Love.<ref name="gjds_pt2">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Initially, the northern Eisenhower bore was used for two-way traffic, with one lane for each direction. The amount of traffic through the tunnel exceeded predictions, and efforts soon began to expedite construction on the southern bore. Construction began on the eastbound Edwin C. Johnson tunnel on August 18, 1975, and finished on December 21, 1979. The initial engineering cost estimate for the Eisenhower bore was $42 million, but the actual cost was $108 million (equivalent to $Template:Inflation million in 2025). Approximately 90% of the funds were paid by the federal government, with the state of Colorado paying the rest. At the time, it set a record for the most expensive federally aided project. The excavation cost for the Johnson bore was $102.8 million (equivalent to $Template:Inflation million in 2025). Not included in the figures is about $50 million in non-boring expenses during the construction of both tunnels.<ref name=Cdoteisenhower2>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=Cdoteisenhower3>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Upon opening, it became the highest-elevation tunnel in the world, taking the title from the Salang Tunnel in Afghanistan.<ref>Template:Cite news</ref>
The tunnel's construction highlighted issues relevant to the feminist movement. When Janet Bonnema applied for a position as an engineering technician with the Colorado Department of Transportation she was given an assignment on the Straight Creek Tunnels project. Her supervisor misread her resume and thought that he was hiring "James." When the supervisor discovered that the department had hired a woman, she was tasked with doing support work from the office. There was opposition to a woman entering the construction site. One supervisor stated that if she entered, "Those workers would flat walk out of that there tunnel and they'd never come back." The workers, most of whom had a mining background, expressed a common superstition that a woman brought bad luck to a mine.<ref name=stbwfm>Template:Cite news</ref> One worker insisted, "It's a jinx. I've seen too many die after a woman was in the tunnel."<ref name=rambler>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Bonnema sued the department for the right to work inside the tunnel. She countered she was in better shape and more agile than most of the men who were working on the tunnel. Emboldened by the passage of an equal rights law in Colorado, she finally entered the tunnel, with an entourage of reporters, on November 9, 1972. Some workers walked off the job, and at least one of them yelled, "Get those women out of here."<ref name=rambler/> She remained determined and re-entered the tunnel a few days later. The next time, she dressed in coveralls and was even assigned tasks on the roof of the tunnel overlooking the men below. Surprised that nobody had apparently noticed that she was a woman, she stated, "I had a good disguise."<ref name=rambler/> Bonnema continued to dress in coveralls during her subsequent work in the tunnel so as not to attract attention.<ref>Template:Cite encyclopedia</ref>
In November 2023, CDOT opened an updated operations center and new garage bays at the tunnels.<ref>Template:Cite press release</ref>
Plane crash during constructionEdit
Template:Main article On Friday, October 2, 1970, during the tunnel's construction, workers constructing the tunnel were among the first on scene of a plane crash that had occurred less than Template:Convert northeast of the east portal.<ref name=gplcrk>Template:Cite news</ref> A Martin 4-0-4 charter aircraft, one of two carrying the college football team of Wichita State University, crashed just north of the highway (Template:Coord). Of the 40 passengers and crew on board, only nine survived.<ref name="NTSB">Template:Cite book </ref> The team was on its way to a game with Utah State University in Logan and had recently refueled at Denver's Stapleton International Airport. The plane carrying the team's starters departed Denver and traveled a poorly planned scenic route. The other plane, carrying reserve players, followed the original route and landed safely in Logan.<ref name=pccwsgt>Template:Cite news</ref>
Water diversionEdit
While the Eisenhower Tunnel was primarily intended as a transportation tunnel, it also serves as a water tunnel for water diversion from the western side of the Continental Divide to the eastern side. Water from the Straight Creek watershed (a tributary of the Blue River), along with all seepage entering the tunnel, is discharged into Clear Creek for delivery to the Coors Brewing Company. Typically, the tunnel delivers over Template:Convert of water per year.<ref>Template:Cite book</ref>
See alsoEdit
- Lists of tunnels
- List of tunnels in the United States
- Moffat Tunnel, the equivalent for rail traffic, opened in 1928
- Salang Tunnel, another among the highest vehicular tunnels at altitude of Template:Convert, in Afghanistan
ReferencesEdit
External linksEdit
Template:Sister project Template:Attached KML
- Eisenhower Tunnel by Colorado Department of Transportation
- Eisenhower Tunnel traffic camera by Colorado Department of Transportation