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26-632: The three major waterfalls are known as the Upper ( 42°34′43″N 78°02′56″W  /  42.5786°N 78.0489°W  / 42.5786; -78.0489  ( Portage Falls, Upper Falls ) ) , Middle ( 42°34′59″N 78°02′34″W  /  42.5831°N 78.0427°W  / 42.5831; -78.0427  ( Portage Falls, Middle Falls ) ) , and Lower Falls ( 42°35′08″N 78°01′13″W  /  42.58565°N 78.02034°W  / 42.58565; -78.02034  ( Portage Falls, Lower Falls ) ) and pass through Portage Canyon in

52-484: A canoe in the lake; estate of Wm. P. Letchworth, which was later made into Letchworth State Park; a man sitting beside a tent, bridge beyond." A portage is the carrying of a boat between two bodies of water to bypass an impassable stretch. The Buffalo & New York Railroad and Erie Railroads advised passengers: "N.B. Pleasure seekers desirous of visiting Portage Falls and the High Bridge can leave Buffalo on

78-573: A dead-end track, rather than a bridge. One of the longest trestle spans created was for railroad traffic crossing the Great Salt Lake on the Lucin Cutoff in Utah . It was replaced by a fill causeway in the 1960s, and is now being salvaged for its timber. Many wooden roller coasters are built using designs similar to trestle bridges because such a structure can be strong and support

104-454: A high track path while using a relatively small amount of material. Since loads are well distributed through large portions of the structure it is also resilient to the stresses imposed. The structure also naturally leads to a certain redundancy (provided that economic considerations are not overly dominant). Such wooden coasters, while limited in their path (not supporting loops), possess a certain ride character (owing to structural response) that

130-400: A pan/hopper for loading and carrying material. The pan has a tapered horizontal front cutting edge that cuts into the soil like a carpenter's plane or cheese slicer and fills the hopper which has a movable ejection system. The horsepower of the machine, depth of the cut, type of material, and slope of the cut area affect how quickly the pan is filled. When full, the pan is raised,

156-546: A pulled trailer that could excavate and pick up earth as it moved. He approached bulldozer manufacturer Caterpillar in the mid-1930s with his idea, but it was turned down, so he founded his own company . The first Tournapull, called the Model A, was rolled out of his factory and into trials in 1937. This concept was further developed by LeTourneau Westinghouse Company. Most current scrapers have two axles, although historically tri-axle configurations were dominant. The scraper

182-424: A short distance. With the pan set close to the ground, a higher speed will spread the material more thinly over a larger area. In an "elevating scraper" a conveyor moves material from the cutting edge into the hopper. R.G LeTourneau conceived the idea of the self-propelled motor scraper while recovering from a near-fatal auto accident. He was an earth moving contractor dealer in bulldozer accessories and envisaged

208-525: Is a bent . A trestle differs from a viaduct in that viaducts have towers that support much longer spans and typically have a higher elevation. Timber and iron trestles (i.e. bridges) were extensively used in the 19th century, the former making up from 1 to 3 percent of the total length of the average railroad. In the 21st century, steel and sometimes concrete trestles are commonly used to bridge particularly deep valleys, while timber trestles remain common in certain areas. Many timber trestles were built in

234-407: Is a large piece of equipment which is used in mining, construction, agriculture and other earthmoving applications. The rear part has a vertically moveable hopper (also known as the bowl) with a sharp horizontal front edge. The hopper can be hydraulically lowered and raised. When the hopper is lowered, the front edge cuts into the soil or clay like a plane and fills the hopper. When the hopper

260-551: Is a modern structure with a long expected lifetime compared to a wooden trestle. Being less susceptible to fire damage in this brushy location is also an advantage. The approaches to the Kate Shelley High Bridge near Boone, Iowa, are steel trestles. New Orleans utilizes steel trestles to support parts of I-10 , the Pontchartrain Expressway , and Tulane Avenue . Also, trestles support

286-527: Is appreciated by fans of the type. The Camas Prairie Railroad in northern Idaho utilized many timber trestles across the rolling Camas Prairie and in the major grade, Lapwai Canyon. The 1,490-foot (450 m) viaduct across Lawyers Canyon was the exception, constructed of steel and 287 feet (87 m) in height. The floodway of the Bonnet Carré Spillway in St. Charles Parish, Louisiana,

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312-783: Is crossed by three wooden trestles each over 1.5 miles (2.4 km) in length. The trestles are owned by the Canadian National Railway (two trestles) and the Kansas City Southern Railroad. The trestles were completed in 1936, after construction of the Spillway. The trestles may be the longest wooden railroad trestles remaining in regular use in North America. A coal trestle is a rigid-frame trestle supporting train tracks above chutes, used to deliver fuel to boats or trains beneath it. At

338-409: Is full (8 to 34 m or 10 to 44 cu yd heaped, depending on type) it is raised, and closed with a vertical blade (known as the apron). The scraper can transport its load to the fill area where the blade is raised, the back panel of the hopper, or the ejector, is hydraulically pushed forward and the load tumbles out. Then the empty scraper returns to the cut site and repeats the cycle. On

364-587: The Great Lakes ports of Buffalo (on Lake Erie ), Sodus Point and Oswego, New York (both on Lake Ontario ). In the United Kingdom, timber trestles were relatively short-lived as a structural type, one of their major uses being to cross the many deep valleys in Cornwall on the spinal rail route through the county. These were all replaced by masonry viaducts. Few timber trestles survived into

390-427: The 'elevating scraper' the bowl is filled by a type of conveyor arrangement fitted with a horizontal flights to move the material engaged by the cutting edge into the bowl as the machine moves forward. Elevating scrapers do not require assistance from push-tractors. The pioneer developer of the elevating scraper was Hancock Manufacturing Company of Lubbock, Texas USA. Scrapers can be very efficient on short hauls where

416-404: The 19th and early 20th centuries with the expectation that they would be temporary. Timber trestles were used to get the railroad to its destination. Once the railroad was running, it was used to transport the material to replace trestles with more permanent works, transporting and dumping fill around some trestles and transporting stone or steel to replace others with more permanent bridges. In

442-514: The 20th century. Two that did, and which are still in daily use, cross the Afon Mawddach on the coast of Wales only a few miles apart, at Barmouth and Penmaenpool . The former, built in 1867, carries trains on the heavy rail Cambrian Coast Line travelling from England via Shrewsbury to the various small towns on Cardigan Bay . It also carries a toll-path for pedestrians. Road traffic at this location has to travel many miles around

468-519: The Lightening train at 6:15 or Mail at 9:35 A.M., and returning, leave Portage at 5:35 and arrive in Buffalo at 9:00, giving them over nine hours at Portage for the enjoyment of scenery unsurpassed in wild and picturesque beauty and sublimity." The Genesee Valley Canal was constructed to allow boat traffic to bypass the falls, A 400 foot viaduct was built across the river. In 1853, a wooden bridge

494-401: The apron is closed, and the scraper transports its load to the fill area . There the pan height is set and the lip is opened (the lip is what the bottom edge of the apron is called), so that the ejection system can be engaged for dumping the load. The forward momentum or speed of the machine affects how big an area is covered with the load. A high pan height and slow speed will dump the load over

520-532: The elevated railroad leading to and from the Huey P. Long Bridge . The first major prestressed concrete trestle railroad bridge built was the Atlantic Coast Line's Salkehatchie River trestle. Wheel tractor-scraper In civil engineering , a wheel tractor-scraper (also known as a land scraper , land leveler or tournapull ) is a type of heavy equipment used for earthmoving . It has

546-656: The estuary to cross at either (for light traffic) the second trestle bridge, at Penmaenpool, which is a toll bridge; or (for heavy traffic) at Dolgellau even further up the estuary. Trestles in cast- or wrought-iron were used during the 19th century on the developing railway network in the United Kingdom. These generally carried decking consisting of some form of trussed girder, as at Crumlin Viaduct, Belah and Meldon ; though two rare examples, at Dowery Dell (demolished in 1962), and Bennerley had lattice girder decks. The steel trestle at Martinez, California, shown below,

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572-612: The falls. A collection of stereoscopic views from 1875 in the New York Public Library's collection includes: "Views of Portage and vicinity including the Genesee River; waterfalls; wooden and iron railroad bridges, including ruins of the wooden bridge; a "canalduct" (Genesee Canal?); Genesee Valley Sand Stone quarry showing men working; Catlin House, Cascade House, and Glen Iris, including group playing croquet and

598-414: The later 20th century, tools such as the earthmover made it cheaper to construct a high fill directly instead of first constructing a trestle from which to dump the fill. Timber trestles remain common in some applications, most notably for bridge approaches crossing floodways , where earth fill would dangerously obstruct floodwater. For the purposes of discharging material below, a coal trestle carried

624-572: The southern section of the state park. A stone bridge just below the Lower Falls is part of a trail in the park. The Middle Falls are the highest. Above the Upper Falls, an active railroad trestle passes over the gorge. Thomas Cole painted the falls in 1839. Stereoscopic views of the falls were also created. In 1843, geologist James Hall studied the rock formations and strata in the area. His publication included hand colored drawings of

650-411: The top of the trestle, rolling stock (typically hopper cars ) open doors on their undersides or on their sides to discharge cargo. Coal trestles were also used to transfer coal from mining railroads to rail cars. They were prominent when coal was an important fuel for rail locomotion and steamships , before they were replaced with mechanical coal loaders during the 20th century. Coal trestles were used in

676-433: Was constructed across the gorge. Trestle bridge A trestle bridge is a bridge composed of a number of short spans supported by closely spaced frames. A trestle (sometimes tressel) is a rigid frame used as a support, historically a tripod used to support a stool or a pair of isosceles triangles joined at their apices by a plank or beam such as the support structure for a trestle table . Each supporting frame

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