Spiral bridge

A spiral bridge, loop 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
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
South Dakota Highway 87 in Wind Cave National Park	South Dakota, United States		43.601215°N 103.494340°W
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
A bridge on US Route 441 between Gatlinburg, Tennessee and Cherokee, North Carolina at Bearpen Hollow in the Great Smoky Mountains National Park	Tennessee, United States[1]		35.635036°N 83.466047°W
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 43.869383°N 103.435572°W 43.874979°N 103.439530°W
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
Astoria–Megler Bridge south approach (U.S. Route 101).	Astoria, Oregon, United States		46.187590°N 123.853260°W
Zuidweg Bridge	Zoetermeer, Netherlands		52.047468°N 4.475218°E
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.
Wiadukt Stanisława Markiewicza	Warsaw, Poland	1904	In Ulica Karowa which connects Krakowskie Przedmiescie to river level,
A-7000 (previously C-345)	Málaga-Colmenar road, Spain		2 spiral tunnels at 36.775796°N 4.379339°W
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.[2]
Route de Cilaos	Réunion		21.181180°S 55.454704°E
Sa Calobra	Majorca, Spain		39.831968°N 2.81574°E
N8 Bypass Brienzwiler	Switzerland		46.750521°N 8.108833°E
Isenfluh	Switzerland
A6 Highway	Italy		44.320409°N 8.377118°E
SP99 just north of Bolzano	Italy		Named Schneckentunnel, German for snail tunnel
Antirio to Lamia highway (E65)	Greece		on the climb of Mount Parnassos to Delphi, Greece. 270° spiral using an overpass.
S232 Bridge South Approach	Changzhou, China		31.715834°N 120.068168°E
Weidun Road Bridge	Changzhou, China		31.722803°N 120.059752°E
Caiyuanba Bridge South Approach	Chongqing, China		29.5360605°N 106.551513°E
Rongqiao Road Spiral Bridge	Chongqing, China		Triple Loop Bridge 29.5262731°N 106.5449174°E
Jialing Jiahua Bridge Approach	Chongqing, China		29.5606004°N 106.5174331°E
Zhoutouju Tunnel Approach	Guangzhou, China		23.0985181°N 113.2520531°E
Nansha Bridge Hai'ou Exit	Guangzhou, China		Interchange made of ramps from spiraling up to the Nansha Bridge. 22.889226°N 113.543465°E
New Clear Water Bay Road	Hong Kong, China		22.331717°N 114.224617°E
Tianmen Shan Big Gate Road, Tianmen Mountain National Park (2 bridges)	Hunan, China		29.05424°N 110.48344°E 29.06547°N 110.48211°E
Yanbai Yellow River Bridge North Approach	Lanzhou, China		36.0789724°N 103.8814573°E
Nanpu Bridge Puxi Approach	Puxi, Shanghai, China	2004
G329 South Bridge Approach	Shaoxing, China		30.0218999°N 120.7308062°E
Huanggang Port Approach	Shenzhen, China
Tianxingzhou Yangtze River Bridge Tianxingzhou Exit	Wuhan, China		30.674541°N 114.387798°E
Jinchang Road Bridge	Wuxi, China		Double loop bridge on each approach 31.556633°N 120.330889°E
G4011 Runyang Yangtze River Bridge Shiye Exit	Zhenjiang, China		32.2201231°N 119.3682047°E
Sendonmatsuo Bridge Approaches	Osaka, Japan		Double loop bridge on each approach 34.6324803°N 135.4759645°E
Shinkizugawao Bridge North Approach	Osaka, Japan		34.62866°N 135.4623977°E
Prefectural Road 53 Onawaba Bridge east approach	Gifu, Japan		35.423410°N 136.744817°E
Kawazu-Nanadaru Loop Bridge	Kawazu, Japan	1981	Double loop bridge. 34.791°N 138.938°E
Mizukami Loop Bridge	Mizukami, Kumamoto, Japan		32.315°N 131.01°E
Yurikamome approach to Rainbow Bridge	Tokyo, Japan		From the mainland.
Cahill Expressway	Sydney, New South Wales, Australia.		Spiral turns left in order to turn right.

Spiral bicycle bridges

• the bridge over the mainline and narrow-gauge railways just west of Wernigerode Hauptbahnhof station in the Harz, Germany has a spiral at each end

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

• Hairpin turn
• Roads section of railway spiral article

References

1. "Google Maps". Google Maps.
2. J.W. Parker, The roads and railroads, vehicles, and modes of travelling, of ancient and modern countries, p. 154

Further reading

• Bernie Hunhoff, The Man Who Designed the Pigtails, South Dakota Magazine, 27 July 2006,
• Jim Pisarowicz, Pigtail Bridge, Wind Cave National Park, National Park Service
• Brochure, Welcome to the Peter Norbeck Scenic Byway, United States Forest Service
• Missouri River Bridges of South Dakota, 1920 to 1980, interview of Kenneth R. Scurr, Former South Dakota Bridge Engineer, by Emory Johnson, So. Dakota State University