The Eisenhower Tunnel, officially the Eisenhower–Edwin C. Johnson
Memorial Tunnel, is a dual-bore, four-lane vehicular tunnel in the
western United States, approximately sixty miles (97 km) west of
Denver, Colorado. The tunnel carries Interstate 70 (I-70) under the
Continental Divide in the Rocky Mountains.
With a maximum elevation of 11,158 feet (3,401 m) 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. With the completion of the second bore in
1979, it was one of the last major pieces of the Interstate system to
Opened 45 years ago 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 governor and U.S. Senator who lobbied
for an Interstate Highway to be built across Colorado.
1.1 Height restriction
1.2 Alternate route
2.1 Plane crash
3 Water diversion
4 See also
6 External links
The Eisenhower bore (westbound tunnel) is 1.693 miles (2.72 km)
long while the Johnson bore (eastbound tunnel) is 1.697 miles
(2.73 km) long. The tunnels are sloped with a 1.64% grade, with
an elevation of 11,013 feet (3,357 m) at the east portal and
11,158 feet (3,401 m) at the west portal. At the time of
dedication, they were the highest vehicular tunnels in the world.
While the Eisenhower
Tunnel remains the highest vehicular tunnel in
the United States, higher tunnels have since been constructed
elsewhere, such as the Fenghuoshan Tunnel, a rail tunnel in China.
The Eisenhower tunnel is noted as the longest mountain tunnel and
highest point on the Interstate Highway System. The tunnel bores
measure 48 by 40 feet (15 by 12 m); however, the portion
accessible to the public is a rectangular shape measuring just over 16
feet (4.9 m) tall. The rest of the bore is used for forced air
ventilation and water drainage systems.
Eastern portal of the tunnel in 2008
Due to additional height restrictions from variable-message signs and
lighting systems, the tunnels' original posted clearance was 13.5 feet
(4.1 m). The trucking industry lobbied the
of Transportation (CDOT) to increase the vertical clearance. With a
2007 retrofit that used lower profile lighting and signs, trucks 13.92
feet (4.24 m) can navigate the tunnel, an increase of 5 inches
(13 cm) over the original limit.
Sensors activate audible sirens near each entrance of the tunnel if a
vehicle above the posted height attempts to enter the tunnel. Traffic
signals at that entrance will turn red, stopping all traffic. The
entrance will remain closed until the vehicle is removed from the
freeway, sometimes causing severe delays for all traffic. 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. Another
feature of the retrofit monitors truck weight—a safe speed for each
truck on the 7% grades and curves just outside the tunnel is
calculated and displayed for each driver.
Inside the tunnel in 2008
To mitigate the dangers posed by a fire inside the tunnel, trucks
hauling hazardous materials are also prohibited from using the tunnel.
Prohibited trucks, bicycles, pedestrians and those who wish to stop
and view the scenery must take the longer and steeper climb and
descent of the older U.S. Highway 6 across Loveland Pass, 834 feet
(254 m) higher at 11,992 feet (3,655 m) above sea level.
Other than the above exceptions, the tunnel has replaced the pass for
general vehicular traffic. While less formidable than the older route,
the approach to the tunnel on both sides is steep, and runaway truck
ramps are available for truckers who lose control.
During construction or winter storms that require closing Loveland
Pass, there is a procedure in place to allow hazardous material trucks
to use the tunnel. Once per hour, the tunnel bores will be closed to
regular traffic, and the trucks will be guided through the tunnel in a
convoy with escorts.
As of December 2009, almost 276 million vehicles have passed through
the tunnel. This figure includes a significant number of visitors to
Colorado's ski resorts.
Western portal to the tunnel. The traffic signal is controlled by a
truck height sensor and control personnel.
The idea for a tunnel under
Loveland Pass existed at least since the
1940s. Serious discussion began when the state of
Interstate Highway System
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 U.S. Route 6 corridor.
Engineers recommended to tunnel under the pass, rather than attempt to
build a route across it that conformed to Interstate Highway
The Eisenhower–Johnson Memorial
Tunnel was known as the Straight
Tunnel during construction, 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
Dwight D. Eisenhower and Edwin C.
Johnson. Construction on the first bore of the tunnel was started on
March 15, 1968. Construction efforts suffered many setbacks and the
project went well over time and budget. 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. 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. Despite the best efforts of engineers, three workers
were killed boring the first tube, and four in boring the second.
Further complicating construction, the boring machines could not work
as fast as expected at such high elevations; 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". Though the project was supposed to take three
years, the tunnel was not opened to traffic until March 8, 1973.
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
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; the actual cost was $108 million (equivalent to
$595 million in 2018). Approximately 90% of the funds were paid by the
federal government, with the state of
Colorado paying the rest. At the
time, this figure set a record for the most expensive federally aided
project. The excavation cost for the Johnson bore was $102.8 million
(equivalent to $347 million in 2018). Not included in these figures is
about $50 million in non-boring expenses in the construction of both
Portal in summer 1978
The tunnel construction became unintentionally involved in the women's
rights 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, but
her supervisor misread her resume and thought he was hiring "James".
When the supervisor discovered the department had hired a woman, she
was instead 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. One worker insisted, "It's a jinx.
I've seen too many die after a woman was in the tunnel." 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
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 did walk off the job; at
least one yelled, "Get those women out of here". 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 apparently
noticed she was a woman, she stated, "I had a good disguise".
Main article: Wichita State University football team plane crash
During construction in 1970, a plane crash occurred less than two
miles (3 km) northeast of the east portal on Friday, October
Martin 4-0-4 charter aircraft, one of two carrying the
college football team of Wichita State University, crashed just north
of the highway (39°41′37″N 105°52′57″W / 39.6935°N
105.8825°W / 39.6935; -105.8825). Of the 40 passengers and crew on
board, only nine survived. 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 incident 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. Workers constructing
the tunnel were among the first on scene at the crash site.
As with the Moffat Tunnel, 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 300 acre-feet (370,000 m3) of
water per year.
Lists of tunnels
Moffat Tunnel, the equivalent for rail traffic, opened in 1928
Salang Tunnel, another among the highest vehicular tunnels at altitude
11,200 feet (3,400 m), in Afghanistan
Rohtang Tunnel, another among the highest vehicular tunnels (length
5.5 miles (8.8 km), altitude 10,200 feet (3,100 m)), in
eastern Himalayas in North India
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