Zion – Mount Carmel Highway

The Zion – Mount Carmel Highway is a 25-mile (40 km) long road in Washington and Kane counties in southern Utah, United States, that is listed on the National Register of Historic Places and is a National Historic Civil Engineering Landmark.[1][2]

Zion – Mount Carmel Highway
The east portal of the Zion-Mt. Carmel Tunnel, September 1929
Zion – Mount Carmel Highway is located in Utah
Zion – Mount Carmel Highway
Zion – Mount Carmel Highway is located in the United States
Zion – Mount Carmel Highway
LocationBetween South Entrance of Zion National Park (on the border with Springdale
Nearest citySpringdale
Coordinates37°13′19″N 112°55′58″W
Built1930
ArchitectMacDonald,Thomas; et al.
MPSZion National Park MRA
NRHP reference No.86003709
Added to NRHPJuly 07, 1987[1]

Description

The highway consists of the eastern half of Utah State Route 9. It begins northeast of Springdale and runs east into Zion National Park, where it passes through the 1.1 miles (1.8 km) long Zion-Mount Carmel Tunnel. After exiting the park, the highway continues east to U.S. Route 89 at Mount Carmel Junction. The road became part of a loop tour of Zion, Bryce Canyon National Park, Cedar Breaks National Monument, and the North Rim of Grand Canyon National Park.[3]

Design and construction
West end of the Pine Creek Bridge and the east portal of the Zion-Mt. Carmel Tunnel, c. 2006
A horseback party at the western entrance to the Zion-Mt. Carmel Tunnel, September 1929. The tunnel shortened the distance from Zion National Park to Bryce Canyon National Park by 70 miles (110 km).

The route was surveyed in 1923 by B.J. Finch, district engineer of the US Bureau of Public Roads, Howard C. Means, a Utah state engineer, and John Winder, a local rancher. The National Park Service evaluated alternative routes, including one that used Parunuweap Canyon (following the East Fork Virgin River), but settled on the Pine Creek route, which required a tunnel through the Great Arch. Detailed design work on the road was carried out by the Bureau of Public Roads. Details including bridges, retaining walls, culverts, and other features were designed by the National Park Service Branch of Plans and Design under the supervision of Thomas Chalmers Vint. Work began in 1927 on a total of 25 miles (40 km) of road, which was completed in 1930.[4]

The highway features a 5,613-foot (1,711 m) tunnel that follows the profile of the Pine Creek Canyon wall at a consistent distance of 21 feet (6.4 m) from the outside face of the rock to the centerline of the tunnel. The west portal is framed by a masonry facade of cut sandstone, while the east portal is a naturalistically formed hole in the rock, entered directly from a bridge. Construction proceeded using mining techniques rather than traditional tunneling techniques, starting from a stope and working outward to the portals.[5] The tunnel uses galleries to provide light and ventilation through the canyon wall to the outside air. The galleries also provided a place to dispose of rock generated during construction, which was dumped through the galleries into the canyon. Parking spaces were originally provided at the galleries, but were discontinued due to safety concerns. Some galleries have been repaired and partially closed with concrete due to damage from rockslides. The interior of the tunnel is rock-faced, with concrete reinforcement at selected locations.

Work on the tunnel was started in 1927 by the Nevada Construction Company and was completed in 1930 at a cost of $503,000 (equivalent to $9.64 million in 2022).[4] At the time of its completion it was the longest non-urban road tunnel in the United States.[6] The tunnel's restricted dimensions require that vehicles over 11.33 feet (3.45 m) in height or 7.83 feet (2.39 m) in width give advance notice so that two-way traffic can be shut down in the tunnel, allowing oversize vehicles to proceed down the center of the tunnel. Vehicles over 13.08 feet (3.99 m) tall and semi-trailers as well as bicycles and pedestrians are prohibited in the tunnel.[7]

Other significant structures include the Pine Creek and Virgin River Bridges and a second, short tunnel through a rock spur east of the main tunnel.

The Zion – Mount Carmel Highway was added to the National Register of Historic Places on July 7, 1987.[1] The Zion Mt. Carmel Tunnel and Highway was designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers in 2011.[2]

See also

References
  1. "National Register Information System". National Register of Historic Places. National Park Service. March 13, 2009.
  2. "Zion Mt. Carmel Tunnel and Highway, Utah Historical Marker". The Historical Marker Database. Retrieved March 6, 2021.
  3. "PARKitecture in Western National Parks". nps.gov. National Park Service. Retrieved September 2, 2009.
  4. "Classified Structure Inventory: Zion-Mt. Carmel Highway". National Park Service. Retrieved June 19, 2009.
  5. Culbertson, Laura J.; Croteau, Todd A. (1993). "Zion-Mount Carmel Highway Tunnel 1930". Historic American Engineering Record. p. 1. Retrieved June 19, 2009.
  6. "New Mountain Highway Has Mile Long Tunnel" Popular Mechanics, June 1930, pages 926 and 927
  7. "Zion Tunnel". Zion National Park. National Park Service. Retrieved June 19, 2009.
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