- Hairpin turn
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 180º to continue on the road. Such turns in ramps andtrails may be called switchbacks inAmerican English , by analogy with switchback railways. InBritish 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.
Highway s 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. Highways of this style are also generally less costly to build and maintain than highways withtunnel s.On occasion, the road may loop completely, using a tunnel or bridge to cross itself (example on
Reunion Island : coord|21|10|52|S|55|27|17|E).In trail building, an alternative to switchbacks is the
stairway .Roads with hairpin turns
Some roads with switchbacks (hairpin turns) include:
Europe *
Alpe d'Huez in the French Alps, famous for its 21 hairpin bends
*Stelvio Pass with its 48 "Spitzkehren" on the northern ramp is one of the most famous
* Inrallying , the cars slide sideways around hairpins in spectacular style, e.g. at theCol de Turini of theRallye Automobile Monte Carlo
*Hillclimbing is a special kind of automobile racing mainly held of mountains roads with hairpins, which keeps average speeds lower than on tracks
* In bicycle racing, climbs up mountains roads with many U-turns are considered the most difficult, and often feature inTour de France ,Giro d'Italia ,Tour de Suisse and alsoVuelta a España
* The roads aboveMonaco , on the foothills of theAlps ; also seen in Hitchcock's "To Catch a Thief"
* The road up fromLysefjord is famous for its 27 hairpin bends
* TheTrollstigen road from Åndalsnes to Valldal is famous for its 11 characteristic bends
* TheGeiranger road from the famousGeirangerfjord to the mountain pass won the gold on the world exhibition, Paris 1900USA
* City streets:
**Lombard Street (San Francisco)
** Winters Street (Sacramento, California )
* U.S. Highways:
** US 6 throughLoveland Pass over theContinental Divide inColorado .
** US 44/NY 55 inUlster County, New York .
** US 93 on both theNevada andArizona sides ofHoover Dam , though these sections will be bypassed by a new highway alignment and bridge south of the dam, scheduled to open in 2010.
** US 129 around theTennessee /North Carolina border, 318 curves in 11 miles.
** US 191 (Coronado Trail Scenic Byway) inArizona between Morenci and Alpine), has a few switchbacks and about 460 curves. [ [http://www.nationalgeographic.com/traveler/deals/coronado.html?fs=plasma.nationalgeographic.com Coronado Trail, Arizona, Driving Tour @ National Geographic Traveler] ]
** US 441 throughGreat Smoky Mountains National Park on theTennessee /North Carolina border.
* State Highways:
** AZ 89A as it entersOak Creek Canyon inArizona .
** AR 7 in various places inArkansas
** CA 1 south ofBodega Bay, California ; it is shown inAlfred Hitchcock 's film "The Birds", is still in use, and looks much as it did during the filming in the early 1960s
** CA 198 on the ascent from theKaweah River canyon to the Giant Forest area ofSequoia National Park . This portion of CA 198 is known asGenerals Highway .
** MA 2 in theBerkshire Mountains
** WA 20 just east ofWashington Pass inOkanogan County .
** WA 410 betweenCayuse Pass andChinook Pass inMount Rainier National Park , eastern Pierce County.
* Other roads:
**Beartooth Highway inMontana andWyoming
**Blue Ridge Parkway inNorth Carolina andVirginia
**Cherohala Skyway inTennessee andNorth Carolina
**Pali Highway ,Hawaii , connecting WindwardOahu withHonolulu /Leeward Oahu
** Though not a particularly tight one,New York 'sTaconic State Parkway has a hairpin turn in Putnam County, and is signed as an S-curve.
** Historic US 66 (Oatman Highway) between Kingman and Oatman, throughSitgreaves Pass in the Black Mountains,Arizona .Americas
* Mexican
Autopista 95D has a famous hairpin turn known as "La Pera" (The Pear), due to its loose resemblance with that fruit's shape.Asia
* The
World War II -eraBurma Road , constructed over the rugged terrain between the (then) British colony ofBurma andChina has many hairpin curves to accommodate traffic to supply China, then otherwise isolated by sea and land.
* InJapan , there is the known Nikkō Irohazaka, a 1-way switchback mountain road (of course there are 2 separate roads; up and down), located atNikko, Tochigi .
* InMacau , a part of the Guia Circuit is a hairpin turn.
* InIndia , the Gata Loops, a part of the route fromManali to Leh.Australia
* The
Mount Hotham Pass on theGreat Alpine Road in Victoria has numerous hairpin bends, as do the other roads in the region.Motorsports
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 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. See
Hillclimbing (railway) for other railway ascent methods.kiing
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 aflush .)External links
References
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