Spiral bridge

A spiral bridge, loop bridge, helix bridge, or pigtail bridge is a road bridge which loops over its own road, allowing the road to climb rapidly. This is useful in steep terrain, or where the approach road to a bridge would terminate too far from the bridge's end. The shape of the bridge forms a helix, not a spiral.

Hastings Spiral Bridge, 1895

Many multi-storey car parks feature such a design as this.

Spiral ramp to Nanpu Bridge in Shanghai, China

Pigtail bridge
A pigtail bridge on Iron Mountain Road

In the Black Hills of South Dakota, a particular form of spiral bridge, locally called a 'pigtail bridge', was introduced in 1932 by Cecil Clyde Gideon, the self-taught superintendent of Custer State Park turned highway designer. He called them “spiral-jumpoffs”. During the planning for Iron Mountain Road, there was a need to negotiate sudden elevation drops while preserving natural features for this scenic highway; the corkscrew design allowed for a spectacular—albeit expensive—solution to this problem. In order to blend the bridges with their surroundings, natural materials such as local timber were used.

Most pigtail bridges were built by the Civilian Conservation Corps in the 1930s.

List of spiral road bridges
Name Location Year Comment
A-7000 (previously C-345) Málaga-Colmenar road, Spain 2 spiral tunnels at 36.775796°N 4.379339°W / 36.775796; -4.379339
A6 Highway Italy 44.320409°N 8.377118°E / 44.320409; 8.377118
Antirio to Lamia highway (E65) Greece on the climb of Mount Parnassos to Delphi, Greece. 270° spiral using an overpass.
Astoria–Megler Bridge south approach (U.S. Route 101) Astoria, Oregon, United States 46.187590°N 123.853260°W / 46.187590; -123.853260
Cahill Expressway Sydney, New South Wales, Australia. Spiral turns left in order to turn right.
Caiyuanba Bridge South Approach Chongqing, China 29.5360605°N 106.551513°E / 29.5360605; 106.551513
Canal Road Flyover Victoria City, Hong Kong 22.2816003°N 114.1800447°E / 22.2816003; 114.1800447
Corkscrew Bridge, Old East Entrance Road, Yellowstone National Park (abandoned)[1] Wyoming, United States 1904, 1919 44.460000°N 110.117500°W / 44.460000; -110.117500
Eastern Harbour Crossing Victoria City, Hong Kong 22.2886114°N 114.2126683°E / 22.2886114; 114.2126683
G329 South Bridge Approach Shaoxing, China 30.0218999°N 120.7308062°E / 30.0218999; 120.7308062
G4011 Runyang Yangtze River Bridge Shiye Exit Zhenjiang, China 32.2201231°N 119.3682047°E / 32.2201231; 119.3682047
General Artigas Bridge Uruguay and Argentina From Colón, Entre Ríos, Argentina to Paysandú, Paysandú Department, Uruguay, across the Uruguay river. Cantilever bridge with a spiral on the Uruguay side.
Huanggang Port Approach Shenzhen, China
Isenfluh Bern, Switzerland
Jialing Jiahua Bridge Approach Chongqing, China 29.5606004°N 106.5174331°E / 29.5606004; 106.5174331
Jinchang Road Bridge Wuxi, China Double loop bridge on each approach 31.556633°N 120.330889°E / 31.556633; 120.330889
Kawazu-Nanadaru Loop Bridge Kawazu, Japan 1981 Double loop bridge. 34.791°N 138.938°E / 34.791; 138.938
Lincoln Tunnel approach road to west portal (New Jersey Route 495). Weehawken, New Jersey, United States Known locally as "The Helix"
40.767037°N 74.021383°W / 40.767037; -74.021383
Mizukami Loop Bridge Mizukami, Kumamoto, Japan 32.315°N 131.01°E / 32.315; 131.01
N8 Bypass Brienzwiler Switzerland 46.750521°N 8.108833°E / 46.750521; 8.108833
Nanpu Bridge Puxi Approach Puxi, Shanghai, China 2004
Nansha Bridge Hai'ou Exit Guangzhou, China Interchange made of ramps from spiraling up to the Nansha Bridge. 22.889226°N 113.543465°E / 22.889226; 113.543465
New Clear Water Bay Road New Kowloon, Hong Kong 22.331717°N 114.224617°E / 22.331717; 114.224617
Prefectural Road 53 Onawaba Bridge east approach Gifu, Japan 35.423410°N 136.744817°E / 35.423410; 136.744817
Rongqiao Road Spiral Bridge Chongqing, China Triple Loop Bridge 29.5262731°N 106.5449174°E / 29.5262731; 106.5449174
Route de Cilaos Réunion 21.181180°S 55.454704°E / -21.181180; 55.454704
S232 Bridge South Approach Changzhou, China 31.715834°N 120.068168°E / 31.715834; 120.068168
Sa Calobra Majorca, Spain 39.831968°N 2.81574°E / 39.831968; 2.81574
Sembon Matsu Bridge Approaches Osaka, Japan Double loop bridge on each approach 34.6324803°N 135.4759645°E / 34.6324803; 135.4759645
Shinkizugawao Bridge North Approach Osaka, Japan 34.62866°N 135.4623977°E / 34.62866; 135.4623977
South Dakota Highway 87 in Wind Cave National Park[2] South Dakota, United States 1930s 43.601215°N 103.494340°W / 43.601215; -103.494340
SP99 just north of Bolzano Italy Named Schneckentunnel, German for snail tunnel
Steinmen Crossing on Oregon Highway 273, part of Historical U.S. Highway 99 through the Siskiyou Mountains Oregon, United States 42.092091°N 122.589541°W / 42.092091; -122.589541
Tianmen Shan Big Gate Road, Tianmen Mountain National Park (2 bridges) Hunan, China 29.05424°N 110.48344°E / 29.05424; 110.48344
29.06547°N 110.48211°E / 29.06547; 110.48211
Tianxingzhou Yangtze River Bridge Tianxingzhou Exit Wuhan, China 30.674541°N 114.387798°E / 30.674541; 114.387798
Thames Tunnel (planned, not constructed) England 1825-1843 Originally planned to have an underground spiral giving access to road traffic, but this was never built.[3]
The Loop Over Bridge, on U.S. Route 441 between Gatlinburg, Tennessee, and Cherokee, North Carolina, at Bearpen Hollow in the Great Smoky Mountains National Park[4] Tennessee, United States[5] 35.635036°N 83.466047°W / 35.635036; -83.466047
Three bridges on Iron Mountain Road/U.S. Route 16A South Dakota, United States 1930s Known locally as "pigtail bridges"
From south to north:
43.861849°N 103.437623°W / 43.861849; -103.437623
43.869383°N 103.435572°W / 43.869383; -103.435572
43.874979°N 103.439530°W / 43.874979; -103.439530
U.S. Route 61 across Spiral Bridge at Hastings High Bridge Hastings, Minnesota, United States 1895-1951 former location: Approximately 44.745137°N 92.853034°W / 44.745137; -92.853034
Weidun Road Bridge Changzhou, China 31.722803°N 120.059752°E / 31.722803; 120.059752
Wiadukt Stanisława Markiewicza Warsaw, Poland 1904 In Ulica Karowa which connects Krakowskie Przedmiescie to river level,
Yanbai Yellow River Bridge North Approach Lanzhou, China 36.0789724°N 103.8814573°E / 36.0789724; 103.8814573
Yurikamome approach to Rainbow Bridge Tokyo, Japan From the mainland.
Zhoutouju Tunnel Approach Guangzhou, China 23.0985181°N 113.2520531°E / 23.0985181; 113.2520531
Zuidweg Bridge Zoetermeer, Netherlands 52.047468°N 4.475218°E / 52.047468; 4.475218

Spiral bicycle bridges

Spiral pedestrian bridges
  • 1998–2004, Glass Spiral Bridge, Millennium Place, Coventry, England

Turnover bridges

Turnover bridges were a feature of some early British canals such as the Macclesfield. The boats were pulled by a horse, and in locations where the towpath crossed to the opposite bank, the spiral on one side allowed the horse to continue without detaching the tow rope. They were not universally provided as they were more expensive to build, needing to span both the canal and the towpath.

See also

References
  1. Historic American Engineering Record (HAER) No. WY-86, "Corkscrew Bridge, Old East Entrance Road, Sylvan Pass, Lake, Teton County, WY"
  2. Historic American Engineering Record (HAER) No. SD-54, "Pigtail Bridge, Hot Springs, Fall River County, SD"
  3. J.W. Parker, The roads and railroads, vehicles, and modes of travelling, of ancient and modern countries, p. 154
  4. Historic American Engineering Record (HAER) No. TN-35-Q, "The Loop Over Bridge, Gatlinburg, Sevier County, TN"
  5. "Google Maps". Google Maps.

Further reading
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