Hairpin turn

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Hairpin turn in Oregon (May 1973)
Road D2204 ascends to the Col de Braus using hairpin bends in the Alpes Maritimes in the French Alps (43°51′48.53″N 7°25′55.83″E / 43.8634806°N 7.4321750°E / 43.8634806; 7.4321750)
The type of hair pin (bobby pin) from which a 'hairpin turn' takes its name
Some of the 48 hairpin turns near the top of the northern ramp of the Stelvio Pass in Italy.
Hairpin turn on the Mont Ventoux in France
Hairpins on a track to the south of Mont Valier, Pyrenees
One of the most famous NASCAR tracks with hairpin turns was the old Riverside International Raceway in Riverside, California.

A hairpin turn (also hairpin bend, hairpin corner, etc.), named for its resemblance to a hairpin/bobby pin, is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn almost 180° to continue on the road. Such turns in ramps and trails may be called switchbacks in American English, by analogy with switchback railways. In British English 'switchback' is more likely to refer to a heavily undulating road—a use extended from the rollercoaster and the other type of switchback railway.

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 (example on Reunion Island: 21°10′52″S 55°27′17″E / 21.18111°S 55.45472°E / -21.18111; 55.45472).

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

Roads with hairpin turns

Some roads with switchbacks (hairpin turns) include:

Europe

USA

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

Chile

  • The Paso Internacional Los Libertadores has several switchbacks on the Chilean side of the pass. 26 below the tunnel entrance alone.

Asia

  • 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.
Nujiang 72 turns/Baxoi 99 turns
  • In Japan, there is the known Nikkō Irohazaka, a 1-way switchback mountain road (of course 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 Chuzenji, 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: 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).
  • In Macau, a part of the Guia Circuit is a hairpin turn.
  • In India, the Gata Loops, a part of the route from Manali to Leh. And the Agumbe Ghat road from Udupi to Teerthahalli in Karnataka have 13 hairpin turns.
Western Ghats, Kerala
Ancient 18 Hairpin Bends, known as Daha ata wanguwa on the way to/from Kandy/Mahiyanganaya

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. Penalties apply.
  • 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". It is a popular descent for cyclists [6]
  • Corkscrew Road in Montacute,South Australia starts at Gorge Road and winds, as its name suggests, up to Montacute Road. This 2.4 km 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. [7]

Motorsports

Fairmont Hotel Hairpin in Circuit de Monaco.
A WRC car taking a hairpin turn during 2007 Rallye Deutschland.
  • Fairmont Hotel Hairpin is the slowest turn in Formula One
  • Many venues used for motor racing incorporate hairpin turns in the racecourse even if the terrain is relatively level. In this case the purpose is to provide a greater challenge to the drivers, to increase overtaking opportunities or simply increase the lap length without increasing the area occupied by the track.

Railways

If a railway curves back on itself like a hairpin turn, it is called a horseshoe curve. The diameter of the curve, however, is much larger than that of a road hairpin. See this example at Zlatoust[8] 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

  • pigtail bridge

References

  1. ↑ National Road Authority of Norway http://www.vegvesen.no/binary?id=16315
  2. ↑ Coronado Trail, Arizona, Driving Tour @ National Geographic Traveler
  3. ↑ Starting point
  4. ↑ Ending point
  5. ↑ Daha ata wanguwa
  6. ↑ The Ben Lomond Descent
  7. ↑ Corkscrew Road to feature in Santos Tour Down Under
  8. ↑ Zlatoust

External links

Media related to Hairpin turns at Wikimedia Commons

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