Hairpin turn

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Hairpin turn in Oregon, US
A hairpin, after which the feature is named

A hairpin turn (also hairpin bend or hairpin corner) is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn about 180° to continue on the road. It is named for its resemblance to a bent metal hairpin. Such turns in ramps and trails may be called switchbacks in American English, by analogy with switchback railways.

Description

Hairpin turns are often built when a route climbs up or down a steep slope, so that it can travel mostly across the slope with only moderate steepness, and are often arrayed in a zigzag pattern. Highways with repeating hairpin turns allow easier, safer ascents and descents of mountainous terrain than a direct, steep climb and descent, at the price of greater distances of travel and usually lower speed limits, due to the sharpness of the turn. Highways of this style are also generally less costly to build and maintain than highways with tunnels.

On occasion, the road may loop completely, using a tunnel or bridge to cross itself at a different elevation (example on Reunion Island: 21°10′52″S 55°27′17″E / 21.18111°S 55.45472°E / -21.18111; 55.45472). When this routing geometry is used for a rail line, it is called a spiral, or spiral loop.

In trail building, an alternative to switchbacks is the stairway.

Roads with hairpin turns

Some roads with switchbacks (hairpin turns) include:

Europe

United Kingdom:

  • The UK, in particular mountainous Scotland, has many mountain passes with hairpin bends; the Pass of the Cattle (Bealach na Bà) in Scotland has many such turns.
  • Zig Zag Hill in Dorset, England, part of the B3081, is known for being one of the bendiest roads in the country.[1]

Continental Europe:

North America

One of the most famous NASCAR tracks with hairpin turns was the old Riverside International Raceway in Riverside, California
WA 129 in Joseph Canyon
Shafer Trail Road in Canyonlands National Park
See also: Dead Man's Curve

Mexico:

  • Mexican Autopista 95D has a famous hairpin turn which is known as La Pera (The Pear), because it somewhat resembles the shape of that fruit.

Canada:

South America

Chile:

Asia

Nujiang 72 turns/Baxoi 99 turns
Tribhuvan Highway, Nepal
Ancient 18 Hairpin Bends, known as Daha ata wanguwa on the way to/from Kandy/Mahiyanganaya
    • Agumbe Ghat road from Udupi to Teerthahalli in Karnataka have 13 hairpin turns. In fact, most of the Ghats include at least one hairpin turn.
    • Gata Loops, a part of the route from Manali to Leh.
    • Ponmudi Hills in Kerala has 22 hairpin bends to reach the hill top.
    • Valparai-Pollachi road has hairpin bend with 40 bends.
    • Z-Morh in Kashmir has two consecutive hairpin bends, hence the name "Z-Morh" (Z-Bend).
  • In Iraq, the road going up the Sinjar mountains starting from Shangal town to Gune Ezidiya village of the Yazidi sect has between 90–100 hairpin turns over a distance of 20 km (12 mi) from starting point[6] to ending point.[7]
  • In Japan, there is the known Nikkō Irohazaka, a one-way switchback mountain road (there are 2 separate roads; up and down), located at Nikko, Tochigi. This road plays a significant role in Japanese history: The route was popular with Buddhist pilgrims on their way to Lake Chūzenji, which is at the top of the forested hill that this road climbs. There are 48 hairpin turns, each labeled with one of the 48 characters in the Japanese alphabet:[8][9] while the narrow road has been modernized over the years, care has been taken to keep the number of curves constant. Iroha-Zaka ascends more than 1,300 feet (396 m).[citation needed] In Aomori Prefecture, the Tsugaru Iwaki Skyline is a toll road that allows drivers to ascend 2,644 feet (806 m) with an average gradient of 8.66% and sections up to 10%; to 8th station on the stratovolcano, Mount Iwaki. The road is considered to be one of the most dangerous mountain roads in the world due to the gradient and the constant 69 hairpin turns.[10]
  • In Myanmar, The World War II–era Burma Road, constructed over the rugged terrain between the (then) British colony of Burma and China has many hairpin curves to accommodate traffic to supply China, then otherwise isolated by sea and land.

Australia

  • The Mount Hotham Pass on the Great Alpine Road in Victoria has numerous hairpin bends, as do the other roads in the region.
  • Galston Gorge in New South Wales. Vehicles like towed caravans are forbidden on this road, lest the caravan gets jammed and delays other traffic. Special penalties apply if overlength vehicles attempted to take this route.
  • Macquarie Pass in New South Wales, which winds through Macquarie Pass National Park has numerous hairpin bends which used to be so tight that semi-trailers had to stop and reverse to get around.
  • Kangaroo Valley Road in New South Wales, located near Berry.
  • Ben Lomond Road in Tasmania has 6 hairpin bends known as "Jacobs Ladder", which is a popular descent for cyclists.[12]
  • Corkscrew Road in Montacute, South Australia starts at Gorge Road and winds, as its name suggests, up to Montacute Road. This 2.4-kilometre (1.5 mi) road has become famous through the Tour Down Under King of the Mountain climb for the difficulty of riding up the steep and sharp bends.[13]

Motorsports

Grand Hotel Hairpin in Circuit de Monaco.
A WRC car taking a hairpin turn during 2007 Rallye Deutschland

Bicycles

The eastern ramp of the Liniebrug, a bike and footbridge built over the Amsterdam-Rhine Canal near Nigtevecht in the Netherlands in 2018, consists of a pair of hairpin bends.

Railways

If a railway curves back on itself like a hairpin turn, it is called a horseshoe curve. The Pennsylvania Railroad built one in Blair County, Pennsylvania, which ascends the Eastern Continental Divide from the east. However, the radius of curvature is much larger than that of a typical road hairpin. See this example at Zlatoust[14] or Hillclimbing for other railway ascent methods.

Skiing

Sections known as hairpins are also found in the slalom discipline of alpine skiing. A hairpin consists of two consecutive vertical or "closed gates", which must be negotiated very quickly. Three or more consecutive closed gates are known as a flush.

See also

References

  1. ^ "England". Top Hairpin-bends. Retrieved 2019-11-23.
  2. ^ Statens vegvesen, Møre og Romsdal (2001): Vegminner i Møre og Romsdal fylke. Molde.
  3. ^ National Road Authority of Norway http://www.vegvesen.no/binary?id=16315[permanent dead link]
  4. ^ Rødland, Kjartan (2000). Tut og køyr!: vegar og vegplanar i Hordaland 1970–2000. Bergen: Alma mater og Statens vegvesen Hordaland. ISBN 8241902638.
  5. ^ "Travel – National Geographic". www.nationalgeographic.com.
  6. ^ "Wikimapia – Let's describe the whole world!". wikimapia.org.
  7. ^ "Wikimapia – Let's describe the whole world!". wikimapia.org.
  8. ^ "Nikko Travel: Irohazaka Winding Road and Akechidaira Plateau". japan-guide.com.
  9. ^ "NIKKO TOURIST ASSOCIATION". nikko-jp.org. Archived from the original on 2014-08-04.
  10. ^ "About the Tsugaru Iwaki Skyline".
  11. ^ "Wikimapia – Let's describe the whole world!". wikimapia.org.
  12. ^ "The Ben Lomond Descent". mountainbiketasmania.com.au. Archived from the original on 2014-01-25.
  13. ^ "Corkscrew Road for Tour Down Under". adelaidenow.com.au.
  14. ^ "Златоуст - Google Maps". google.com.

External links

Media related to Hairpin turns at Wikimedia Commons

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