PIERCING THE CONTINENTAL DIVIDE -- THE EISENHOWER TUNNEL by Pam North Approximately sixty miles west of Denver, on Interstate 70, is the Eisenhower Tunnel. With an elevation of 11,013 feet at its east portal, and 11,158 at its west portal, it has the distinctions of being the highest vehicular tunnel in the world and the longest tunnel built with interstate funds. While lying entirely within the Arapaho National Forest, it straddles two counties, Clear Creek on the east and Summit on the west. Traveling through the Eisenhower tunnel saves the public the 9.1-mile distance over Loveland Pass on Highway 6. The Eisenhower Tunnel is of twin bore design, and was completed in two phases. The westbound bore (North Tunnel) was begun on March 15, 1968, and was completed five years later on March 8, 1973. This bore was originally called the Straight Creek Tunnel, (the name stemming from the valley where the west portal is located), and later was officially named the Eisenhower Memorial Bore to reflect former president Dwight D. Eisenhower's connections to Denver (his wife was born and reared in Denver, the Eisenhowers were married there in 1916, and they were frequent visitors to Colorado). The second bore's construction was started August 18, 1975, and was finished four years later on December 21, 1979. The eastbound bore was named after Edwin C. Johnson, a past governor and U.S. senator who had actively supported an interstate highway system across Colorado. During construction approximately 1 million cubic yards of material were cleared from each bore, and over 190,000 cubic yards of concrete were used for each tunnel lining. Nearly 6,000 people were employed on the tunnel project throughout its construction. They worked about four million manhours, and during the construction, there were three fatalities on the first bore, and six fatalities on the second bore. Centerline to centerline, the two tunnels are approximately 115 feet apart at the east entrance, 120 feet apart at the west entrance, and some 230 feet apart at the widest point of separation under the mountain. The length of the westbound (north) tunnel is 1.693 miles, and the length of the eastbound (south) tunnel is 1.697 miles. The average grade of both tunnels is 1.64 percent rising toward the west. The westbound tunnel curves slightly to the left about midway into the mountain. The approach grades are steep, 7 percent on the west approach and 6 percent on the east approach. The width of the tunnels is 40 feet, and the actual excavated height for the tunnels is 48 feet, a distance not apparent to motorists. The exhaust and air supply ducts are located above a suspended porcelain enamel panel ceiling, and drainage is provided by a system beneath the road surface. Motorists passing through the tunnel see only the vertical distance, 16 feet, 4 inches, from roadway surface to ceiling, and because of message boards mounted from the ceiling, actual clearance is 13 feet, 6 inches. A total travel width of 26 feet is provided by two traffic lanes of 13 feet in each bore. A walkway running adjacent to the vehicle lanes allows access by tunnel maintenance personnel, and also provides connection between the westbound or eastbound tunnels through three cross-passageways, spaced at 2,000 foot intervals. A reverse lane is periodically implemented on Sunday afternoons during peak traffic weekends to provide uninterrupted traffic flow for eastbound motorists. The nerve center of the tunnel complex is the control room, oufitted with thirty 18-inch color television screens and eight 32-inch color monitors; the cameras can tilt, zoom, and pan left and right. Video monitoring and variable message boards allow maintenance personnel to observe and control traffic inside the tunnels. The tunnel operates 24 hours a day, 365 days a year, with 52 full-time employees. The staff duties include around-the-clock television surveillance, emergency response, tunnel washing and sweeping, ventilation maintenance, heavy equipment servicing and repair, water treatment, and snow removal (annual snowfall in the area averages 315 inches for the months of November through April). The electric bill for tunnel operation averages approximately $70,000 per month. The Eisenhower Tunnel unexpectedly became a flashpoint in the women's liberation movement when a woman named Janet Bonnema sought employment on the project. After meeting the testing qualifications for the job, she was accepted to work on the tunnel, but some error had registered her as male rather than female. After 18 months as an engineering technician, Bonnema still had not been allowed into the tunnel, despite acknowledgement by the state that she was as qualified as any male to work within it. In November, 1972, after the state constitution was amended to guarantee equal rights for women, Bonnema entered the tunnel for the first time, much to the consternation of many male workers who superstitiously believed it was bad luck for women to work in the tunnel. Seventy of the 100 male workers walked off the job in protest, costing the state an estimated $10,000, but they returned the next day to continue the project. The first driver through the Eisenhower tunnel received a summons for trespassing. He had been drinking, and had decided that he should have the honor of being the first person to drive through the tunnel rather than Governor Love. The charge was later dismissed on the grounds that the signs prohibiting entrance to the tunnel were inadequate. In 2002, an annual total of 10.3 million vehicles passed through the Eisenhower Tunnel (about 29,000 per day). On March 23, 2003, just days before the tunnel turned thirty years old, 200 million cars had passed through it since its completion in 1973, without a single traffic fatality. Traffic on the I-70 corrider has increased every year, and the current estimates of 94,00 eastbound and westbound vehicles on any given winter weekend day are expected to increase to 125,000 by 2025. The initial challenge was to build the tunnel - the new obstacle to surmount will be how to handle the rising traffic flow through it. Resource: Colorado Department of Transportation Photo to accompany article is at: http://www.dot.state.co.us/eisenhower/phototour.asp (photo at left -- entrance to tunnel) Caption: Entrance to the Eisenhower Tunnel.