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. Despite its name, the typical shape of a spiral bridge forms a helix, not a spiral.
Many multi-storey car parks feature such a design as this.
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.
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.
The Historic Columbia River Highway is an approximately 75-mile-long (121 km) scenic highway in the U.S. state of Oregon between Troutdale and The Dalles, built through the Columbia River Gorge between 1913 and 1922. As the first planned scenic roadway in the United States, it has been recognized in numerous ways, including being listed on the National Register of Historic Places, being designated as a National Historic Landmark by the U.S. Secretary of the Interior, being designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers, and being considered a "destination unto itself" as an All-American Road by the U.S. Secretary of Transportation. The historic roadway was bypassed by the present Columbia River Highway No. 2 from the 1930s to the 1950s, leaving behind the old two-lane road. The road is now mostly owned and maintained by the state through the Oregon Department of Transportation as the Historic Columbia River Highway No. 100 or the Oregon Parks and Recreation Department as the Historic Columbia River Highway State Trail.
A hairpin turn 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.
Crown Point is a basalt promontory on the Columbia River Gorge and an associated state park in the U.S. state of Oregon. It is located in eastern Multnomah County, approximately 15 miles (24 km) east of Portland. Crown Point is one of the scenic lookouts along the Historic Columbia River Highway, providing a panoramic view of part of the Columbia River. It stands 733 feet (223 m) above the river and is the remains of a lava flow that filled the ancestral channel of the Columbia River 14 to 17 million years ago. The Point was designated a National Natural Landmark in 1971.
The Beartooth Highway is an All-American Road in the western United States on a section of U.S. Route 212 in Montana and Wyoming between Red Lodge and the Northeast entrance of Yellowstone National Park. It crests at Beartooth Pass in Wyoming at 10,947 feet (3,337 m) above sea level, and was called "the most beautiful drive in America," by late CBS News correspondent Charles Kuralt. Because of heavy snowfall at the top, the pass is usually open for about five months per year, from mid-May to mid-October, weather conditions permitting.
The George Washington Memorial Parkway, colloquially the G.W. Parkway, is a 25-mile-long (40 km) parkway that runs along the south bank of the Potomac River from Mount Vernon, Virginia, northwest to McLean, Virginia, and is maintained by the National Park Service (NPS). It is located almost entirely within Virginia, except for a short portion of the parkway northwest of the Arlington Memorial Bridge that passes over Columbia Island within the District of Columbia.
The James River and Kanawha Canal was a partially built canal in Virginia intended to facilitate shipments of passengers and freight by water between the western counties of Virginia and the coast. Ultimately its towpath became the roadbed for a rail line following the same course.
Clara Barton Parkway is an automobile parkway in the U.S. state of Maryland and the District of Columbia. The highway runs 6.8 miles (10.9 km) from MacArthur Boulevard in Carderock, Maryland, east to Canal Road at the Chain Bridge in Washington. Clara Barton Parkway is a two- to four-lane parkway that parallels the Potomac River and the Chesapeake and Ohio Canal (C&O) in southwestern Montgomery County, Maryland, and the far western corner of Washington. The parkway provides access to the communities of Cabin John and Glen Echo and several units of the Chesapeake and Ohio Canal National Historical Park. The Maryland portion of the George Washington Memorial Parkway was constructed from Carderock past Interstate 495 (I-495) to Glen Echo in the early to mid-1960s. The parkway was proposed to continue west to Great Falls and east to Georgetown. However, these proposals never came to fruition and the parkway was extended only to the Chain Bridge in the early 1970s. The Maryland portion of the George Washington Memorial Parkway was renamed in 1989 for Clara Barton, the founder of the American Red Cross, and whose original headquarters is located in Glen Echo.
The Delaware and Hudson Canal was the first venture of the Delaware and Hudson Canal Company, which would later build the Delaware and Hudson Railway. Between 1828 and 1899, the canal's barges carried anthracite coal from the mines of northeastern Pennsylvania to the Hudson River and thence to market in New York City.
Roebling's Delaware Aqueduct, also known as the Roebling Bridge, is the oldest existing wire suspension bridge in the United States. It runs 535 feet over the Delaware River, from Minisink Ford, New York, to Lackawaxen, Pennsylvania. Opened in 1849 as an aqueduct connecting two parts of the Delaware & Hudson Canal (D&H), it has since been converted to carry automotive traffic and pedestrians.
U.S. Highway 16A (US 16A) is a 36.971-mile-long (59.499 km) scenic United States Numbered Highway. It is an alternate route for US 16. It splits from US 16 in the Black Hills of the southwestern part of the U.S. state of South Dakota. The highway's western terminus is an intersection with US 16, US 385, and South Dakota Highway 89 (SD 89) in Custer. The eastern terminus is at an interchange with US 16 called Keystone Wye south of Rapid City. Portions of US 16A are known as the Iron Mountain Road, named after the peak it summits.
The Lehigh Canal is a navigable canal that begins at the mouth of Nesquehoning Creek on the Lehigh River in the Lehigh Valley and Northeastern regions of Pennsylvania. It was built in two sections over a span of 20 years beginning in 1818. The lower section spanned the distance between Easton and present-day Jim Thorpe. In Easton, the canal met the Delaware and Morris Canals, which allowed anthracite coal and other goods to be transported further up the U.S. East Coast. At its height, the Lehigh Canal was 72 miles (116 km) long.
South Dakota Highway 87 (SD 87) is a 37.894-mile-long (60.984 km) state highway in the southwestern part of the U.S. state of South Dakota. It travels through the Black Hills region. The highway's southern terminus is at an intersection with U.S. Route 385 (US 385), about 6 miles (9.7 km) southeast of Pringle, within the southwestern part of Wind Cave National Park. Its northern terminus is at an intersection with US 16/US 385 about 3 miles (4.8 km) south-southwest of Hill City, within the east-central part of the Black Hills National Forest.
The Meridian Highway Bridge is a bridge that formerly carried U.S. Route 81 across the Missouri River between Nebraska and South Dakota. The Meridian Highway Bridge connects Yankton, South Dakota with rural Cedar County, Nebraska. The Meridian Bridge is a double-deck bridge, with the top level having carried traffic into South Dakota from Nebraska, and the lower level having carried traffic into Nebraska from South Dakota. It was closed to all traffic in 2008, but reopened for use only by pedestrians and bicycles in 2011.
Canal Parkway, which carries the unsigned Maryland Route 61 designation, is a state highway and automobile parkway in the U.S. state of Maryland. The road begins at the West Virginia state line at the North Branch Potomac River opposite Wiley Ford, where the highway continues south as West Virginia Route 28. The parkway runs 1.94 miles (3.12 km) north to MD 51 within the city of Cumberland. Canal Parkway provides a connection between downtown Cumberland and the South Cumberland neighborhood and with Greater Cumberland Regional Airport, which is located in Mineral County, West Virginia.
Tinkers Creek Aqueduct is an aqueduct that was constructed to bridge the Ohio and Erie Canal over Tinkers Creek near its confluence with the Cuyahoga River in Valley View, Ohio. It is a relatively rare surviving example of an Ohio and Erie Canal aqueduct. It was originally constructed in 1825-1827 by, and re-built due to flood damage in 1845 and 1905. Tinkers Creek Aqueduct was included in a National Historic Landmark district established in 1966, and it was separately listed on the National Register of Historic Places in 1979. The original Tinkers Creek Aqueduct was a wood plank, steel truss, and Ashlar-sandstone structure constructed in 1827, south of the present aqueduct's location. Cuyahoga River and Tinkers Creek flooding caused continual damage to the original aqueduct, so successive structures were built in 1845 and 1905 in the present location. Today, Tinkers Creek Aqueduct is the only aqueduct which remains of the four original aqueducts in the Cuyahoga Valley. Of Furnace Run Aqueduct, Mill Creek Aqueduct, Peninsula Aqueduct, and Aqueduct; Mill Creek Aqueduct, of newer construction, is the only aqueduct which still carries Ohio and Erie Canal water. After 102 years of flooding, weathering, and deterioration, Tinkers Creek Aqueduct was removed in 2007. The National Park Service is currently working on Phase II of the project to reconstruct it from newer materials.
The Grand Loop Road is a historic district which encompasses the primary road system in Yellowstone National Park. Much of the 140-mile (230 km) system was originally planned by Captain Hiram M. Chittenden of the US Army Corps of Engineers in the early days of the park, when it was under military administration. The Grand Loop Road provides access to the major features of the park, including the Upper, Midway and Lower geyser basins, Mammoth Hot Springs, Tower Fall, the Grand Canyon of the Yellowstone and Yellowstone Lake.
The Peter Norbeck Scenic Byway is a National Scenic Byway in the Black Hills National Forest in the southwestern part of the U.S. state of South Dakota. It is a loop which is composed of portions of U.S. Route 16A (US 16A), South Dakota Highway 244 (SD 244), SD 87, and SD 89. Parts of the byway enter Black Hills National Forest, Custer State Park, and the Mount Rushmore National Memorial; the byway also travels within five miles of the Crazy Horse Memorial. The byway is named after Peter Norbeck, who served as governor of and senator for South Dakota.
The Zion – Mount Carmel Highway is a 25-mile (40 km) long road in Washington and Kane counties in southern Utah, United States, that is listed on the National Register of Historic Places and is a National Historic Civil Engineering Landmark.
Interstate 90 Business may refer to several business routes of the Interstate Highway System that connects Interstate 90 with the central business district of various cities bypassed by I-90. Each business route can be either a business loop or a business spur, depending on whether both ends connect to I-90. The business route in each community is considered a unique route. In many cases, these routes are a former section of a U.S. Route.
The AJX Bridge is a historic Pratt truss bridge in southwestern Johnson County, Wyoming. The bridge was built in 1931 across the South Fork of the Powder River near Kaycee, Wyoming. AJX Bridge was built to provide a river crossing for U.S. Route 87. It was placed on the National Register of Historic Places in 1985 as part of a Multiple Property Submission devoted to historic bridges in Wyoming.
This article includes a list of general references, but it lacks sufficient corresponding inline citations .(November 2010) |