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26-719: The Grand Trunk Bridge is a Canadian steel trestle railway bridge that spans the South Saskatchewan River in Saskatoon , Saskatchewan . It was built in 1908 as part of the Grand Trunk Pacific Railway project. The GTP was merged into the Canadian National Railway (CN) in 1920; as such, the structure is also referred to informally as the CN Railway Bridge . The bridge is the southernmost of

52-428: A fixed roof, are used for cargo like grain , sugar , and fertilizer , and Portland cement that must be protected from exposure to the weather. Open hopper cars, which do not have a roof, are used for commodities such as coal , which can suffer exposure with less detrimental effect. Removable canvas covers are sometimes used to protect moisture sensitive commodities in open hopper cars. Closed hopper cars have

78-507: A machine for grinding grain into flour . Historically, open hopper cars were used to carry coarse mined products like coal , ore , and gravel , while boxcars were used for granular materials requiring protection from the elements. Weatherproof covers were added to hopper cars, creating the covered hopper. Early production emphasized two-bay cars very similar to open coal hoppers and suitable for materials of similar density, like Portland cement or rock-salt . Some cars were available in

104-538: A metal top with waterproof loading hatches, which provides superior protection. These loading hatches along the top of the covered hopper may be a single long opening along the centerline or a pattern of multiple round or square openings positioned to allow uniform weight distribution when loading the car. Some covered hoppers have two to four separate bays, with chutes at the bottom to direct unloading contents. Hopper cars have been used by railways worldwide whenever automated cargo handling has been desired. "Ore jennies"

130-478: 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 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

156-487: A whole train, or may be sent back in smaller quantities on manifest trains (trains which carry just about any type of freight). These trains are used primarily for hauling products such as corn , wheat and barley . The word "hopper", meaning a "container with a narrow opening at bottom", goes back to the thirteenth century, and is found in Chaucer 's story " The Reeve's Tale " (written late fourteenth century) in reference to

182-651: 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 the elevated railroad leading to and from the Huey P. Long Bridge . The first major prestressed concrete trestle railroad bridge built

208-435: 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 is appreciated by fans of the type. The Camas Prairie Railroad in northern Idaho utilized many timber trestles across

234-548: Is predominantly a term for shorter open hopper cars hauling taconite by the Duluth, Missabe and Iron Range Railway on Minnesota 's Iron Range . The Coke Express , a CSX unit train of hopper cars loaded with coke , with the words "Coke Express" painted on the sides of the hoppers. Large unit trains of various grain crops are a common sight in North America , reaching up to 125 cars long. These predominantly haul grain from

260-502: 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 a high track path while using a relatively small amount of material. Since loads are well distributed through large portions of the structure it

286-436: The 1910s, and became more common by the 1940s. These early cars were volume-limited for less dense commodities like grain or sugar , so later designs include longer covered hopper cars with higher sides and three or more bottom bays. Increasing axle load limits have allowed some of the heavier loads formerly assigned to two-bay hoppers to be assigned to larger, more efficient three-bay hoppers. Some covered hopper cars retain

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312-429: 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 the 19th and early 20th centuries with the expectation that they would be temporary. Timber trestles were used to get

338-768: 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 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

364-685: The city's Circle Drive freeway included the Gordie Howe Bridge , built parallel to the Grand Trunk Bridge. In 2016, the city's original Traffic Bridge , opened in 1907, was disassembled to make way for a replacement bridge. As of that moment, the Grand Trunk Bridge became Saskatoon's oldest surviving bridge (it opened several months before the city's second rail bridge ). [REDACTED] Media related to Grand Trunk Bridge (Saskatoon) at Wikimedia Commons Trestle bridge Timber and iron trestles (i.e. bridges) were extensively used in

390-515: The city's two rail bridges and is situated between the Queen Elizabeth Power Station on the upstream (west) side and Diefenbaker Park on the downstream (east) side. CN placed a chain link fence on both sides of the bridge as a result of people trespassing on the walkways. Based upon anecdotal evidence – that is, visual inspection of city maps – it appears to have the longest span of any Saskatoon bridge. The 2012 southwest extension of

416-446: The conventional centersill as a strength member transmitting compression and tension forces from one car to the next. Beginning in the 1960s, designs distributing these forces along the sides of the car eliminated the centersill beam to simplify bulk material handling with wider hopper openings reducing the tendency for bridging to restrict gravity flow when unloading the car. Increase in wheel loads has important implications for

442-514: 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, is a modern structure with a long expected lifetime compared to

468-581: The development of automated handling of such commodities, including automated loading and unloading facilities. Hopper cars are distinguished from gondola cars , which do not have opening doors on their underside or sides. Gondola cars are simpler and more compact because sloping ends are not required, but a rotary car dumper is required to unload them. Some "dual-purpose" hoppers have a rotary coupler on one or both ends, so they can be used in both rotary and bottom-dump operations. Two main types of hopper car exist. Covered hopper cars, which are equipped with

494-672: The large farming areas of the Great Plains to various markets, but a number of unit trains originate from other major farming areas, such as Illinois and Indiana as well as the Canadian provinces of Alberta , Saskatchewan and Manitoba . These trains may originate from a single grain elevator , or may be marshaled in a yard from various locals (short trains which serve nearby industries). The destinations tend to be large flour mills or ports (for export), or they may be split up and delivered to multiple locations. The empty cars may return as

520-566: 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 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

546-399: The rail infrastructure needed to accommodate future grain hopper car shipments. The weight of the car is transmitted to the rails and the underlying track structure through these wheel loads. As wheel loads increase, track maintenance expenses increase and the ability of a given rail weight, ballast depth, and tie configuration to handle prolonged rail traffic decreases. Moreover, the ability of

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572-420: 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 the later 20th century, tools such as the earthmover made it cheaper to construct a high fill directly instead of first constructing

598-614: 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, 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

624-409: 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 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

650-468: 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 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

676-483: Was the Atlantic Coast Line's Salkehatchie River trestle. Hopper car A hopper car ( NAm ) or hopper wagon ( UIC ) is a type of railroad freight car that has opening doors on the underside or on the sides to discharge its cargo. They are used to transport loose solid bulk commodities such as coal , ore , grain , and track ballast . The hopper car was developed in parallel with

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