A railroad tie, crosstie (American English), railway tie (Canadian English) or railway sleeper (British English) is a rectangular support for the rails in railroad tracks. Generally laid perpendicular to the rails, ties transfer loads to the track ballast and subgrade, hold the rails upright and keep them spaced to the correct gauge.
Railroad ties are traditionally made of wood, but prestressed concrete is now also widely used, especially in Europe and Asia. Steel ties are common on secondary lines in the UK;plastic composite ties are also employed, although far less than wood or concrete. As of January 2008, the approximate market share in North America for traditional and wood ties was 91.5%, the remainder being concrete, steel, azobé (red ironwood) and plastic composite.
The crosstie spacing of mainline railroad is approximately 19 to 19.5 inches for wood ties or 24 inches for concrete ties. The number of ties is 3,250 wooden crossties per mile (2019 ties/km, or 40 ties per 65 feet) for wood ties or 2640 ties per mile for concrete ties.Rails in the US may be fastened to the tie by a railroad spike; iron/steel baseplates screwed to the tie and secured to the rail by a proprietary fastening system such as a Vossloh or Pandrol which are commonly used in Europe.
The type of railroad tie used on the predecessors of the first true railway (Liverpool and Manchester Railway) consisted of a pair of stone blocks laid into the ground, with the chairs holding the rails fixed to those blocks. One advantage of this method of construction was that it allowed horses to tread the middle path without the risk of tripping. In railway use with ever heavier locomotives, it was found that it was hard to maintain the correct gauge. The stone blocks were in any case unsuitable on soft ground, such as at Chat Moss, where timber ties had to be used. Bi-block ties with a tie rod are somewhat similar.
Historically wooden rail ties were made by hewing with an axe, called axe ties, or sawn to achieve at least two flat sides. A variety of softwood and hardwoods timbers are used as ties, oak, jarrah and karri being popular hardwoods, although increasingly difficult to obtain, especially from sustainable sources.Some lines use softwoods, including Douglas fir; while they have the advantage of accepting treatment more readily, they are more susceptible to wear but are cheaper, lighter (and therefore easier to handle) and more readily available. Softwood is treated, while creosote is the most common preservative for railway ties, preservatives are also sometimes used such as pentachlorophenol, chromated copper arsenate and a few other preservatives. Sometimes non-toxic preservatives are used, such as copper azole or micronized copper. New boron-based wood preserving technology is being employed by major US railroads in a dual treatment process in order to extend the life of wood ties in wet areas. Some timbers (such as sal, mora, jarrah or azobé) are durable enough that they can be used untreated.
Problems with wooden ties include rot, splitting, insect infestation, plate-cutting, also known as chair shuffle in the UK (abrasive damage to the tie caused by lateral motion of the tie plate) and spike-pull (where the spike is gradually loosened from the tie). Wooden ties can catch fire; as they age they develop cracks that allow sparks to lodge and more easily start fires.
Concrete ties are cheaper and easier to obtain than timber[ dubious ] and better able to carry higher axle-weights and sustain higher speeds. Their greater weight ensures improved retention of track geometry, especially when installed with continuous-welded rail. Concrete ties have a longer service life and require less maintenance than timber due to their greater weight, which helps them remain in the correct position longer. Concrete ties need to be installed on a well-prepared subgrade with an adequate depth on free-draining ballast to perform well. Concrete ties amplify wheel noise, so wooden ties are often used in densely populated areas.
On the highest categories of line in the UK (those with the highest speeds and tonnages), pre-stressed concrete ties are the only ones permitted by Network Rail standards.
Most European railways also now use concrete bearers in switches and crossing layouts due to the longer life and lower cost of concrete bearers compared to timber, which is increasingly difficult and expensive to source in sufficient quantities and quality.
Steel ties are formed from pressed steel and are trough-shaped in section. The ends of the tie are shaped to form a "spade" which increases the lateral resistance of the tie. Housings to accommodate the fastening system are welded to the upper surface of the tie. Steel ties are now in widespread use on secondary or lower-speed lines in the UK where they have been found to be economical to install due their ability to be installed on the existing ballast bed. Steel ties are lighter in weight than concrete and able to stack in compact bundles unlike timber. Steel ties can be installed onto the existing ballast, unlike concrete ties which require a full depth of new ballast. Steel ties are 100% recyclable and require up to 60% less ballast than concrete ties and up to 45% less than wood ties.
Historically, steel ties have suffered from poor design and increased traffic loads over their normally long service life. These aged and often obsolete designs limited load and speed capacity but can still be found in many locations globally and performing adequately despite decades of service. There are great numbers of steel ties with over 50 years of service and in some cases they can and have been rehabilitated and continue to perform well. Steel ties were also used in specialty situations, such as the Hejaz Railway in the Arabian Peninsula, which had an ongoing problem with Bedouins who would steal wooden ties for campfires.
Modern steel ties handle heavy loads, have a proven record of performance in signalized track, and handle adverse track conditions. Of high importance to railroad companies is the fact that steel ties are more economical to install in new construction than creosote-treated wood ties and concrete ties. Steel ties are utilized in nearly all sectors of the worldwide railroad systems including heavy-haul, class 1s, regional, shortlines, mining, electrified passenger lines (OHLE) and all manner of industries. Notably, steel ties (bearers) have proven themselves over the last few decades to be advantageous in turnouts (switches/points) and provide the solution to the ever-growing problem of long timber ties for such use.
When insulated to prevent conduction through the ties, steel ties may be used with track circuit based train detection and track integrity systems. Without insulation, steel ties may only be used on lines without block signaling and level crossings or on lines that use other forms of train detection such as axle counters.
In more recent times, a number of companies are selling composite railroad ties manufactured from recycled plastic resinsand recycled rubber. Manufacturers claim a service life longer than wooden ties with an expected lifetime in the range of 30–80 years, that the ties are impervious to rot and insect attack, and that they can be modified with a special relief on the bottom to provide additional lateral stability. In some main track applications the hybrid plastic tie has a recessed design to be completely surrounded by ballast.
Aside from the environmental benefits of using recycled material, plastic ties usually replace timber ties soaked in creosote, the latter being a toxic chemical,and are themselves recyclable. Hybrid plastic railroad ties and composite ties are used in other rail applications such as underground mining operations, industrial zones, humid environments and densely populated areas. Hybrid railroad ties are also used to be partly exchanged with rotten wooden ties, which will result in continuous track stiffness. Hybrid plastic ties and composite ties also offer benefits on bridges and viaducts, because they lead to better distribution of forces and reduction of vibrations into respectively bridge girders or the ballast. This is due to better damping properties of hybrid plastic ties and composite ties, which will decrease the intensity of vibrations as well as the sound production. In 2009, Network Rail announced that it would begin replacing wooden ties with recycled plastic. but I-Plas became insolvent in October 2012.
In 2012, New Zealand ordered a trial batch of "EcoTrax" brand recycled composite ties from Axion for use on turnouts and bridges,and a further 3-year order in 2015, but then Axion filed for bankruptcy in December 2015, though it continues to trade. These ties are developed by Dr. Nosker at Rutgers University.
Ties may also be made from fiberglass.
An unusual form of tie is the Y-shaped tie, first developed in 1983. Compared to conventional ties the volume of ballast required is reduced due to the load-spreading characteristics of the Y-tie.Noise levels are high but the resistance to track movement is very good. For curves the three-point contact of a Y steel tie means that an exact geometric fit cannot be observed with a fixed attachment point.
The cross section of the ties is an I-beam.
As of 2006 less than 1,000 km (621 mi) of Y-tie track had been built, of which approximately 90 percent is in Germany.
The ZSX Twin tie is manufactured by Leonhard Moll Betonwerke GmbH & Co KG and is a pair of two pre-stressed concrete ties longitudinally connected by four steel rods.The design is said to be suitable for track with sharp curves, track subject to temperature stress such as that operated by trains with eddy brakes, and bridges, and as transition track between traditional track and slab track or bridges.
Concrete monoblock ties have also been produced in a wider form (e.g. 57 cm or 22 1⁄2 in) such that there is no ballast between the ties; this wide tie increases lateral resistance and reduces ballast pressure. The system has been used in Germany where wide ties have also been used in conjunction with the GETRAC A3 ballastless track systems.
Bi-block (or twinblock) ties consist of two concrete rail supports joined by a steel bar. Advantages include increased lateral resistance and lower weight than monobloc concrete ties, as well as elimination of damage from torsional forces on the ties center due to the more flexible steel connections.This tie type is in common use in France, and are used on the high-speed TGV lines. Bi-block ties are also used in ballastless track systems. Gauge convertible by cutting bar and welding extra bar to suit new gauge.
Frame ties (German: Rahmenschwelle) comprise both lateral and longitudinal members in a single monolithic concrete casting.This system is in use in Austria; in the Austrian system the track is fastened at the four corners of the frame, and is also supported midway along the frame. Adjacent frame ties are butted close to each other. Advantages of this system over conventional cross increased support of track. In addition, construction methods used for this type of track are similar to those used for conventional track.
In ladder track the ties are laid parallel to the rails and are several meters long. The structure is similar to Brunel's baulk track; these longitudinal ties can be used with ballast, or with elastomer supports on a solid non-ballasted support.
Various methods exist for fixing the rail to the railroad ties. Historically spikes gave way to cast iron chairs fixed to the tie, more recently springs (such as Pandrol clips) are used to fix the rail to the tie chair.
In recent years, wooden railroad ties have also become popular for gardening and landscaping, both in creating retaining walls and raised-bed gardens, and sometimes for building steps as well. Traditionally, the ties sold for this purpose are decommissioned ties taken from rail lines when replaced with new ties, and their lifespan is often limited due to rot. Some entrepreneurs sell new ties. Due to the presence of wood preservatives such as coal tar, creosote or salts of heavy metals, railroad ties introduce an extra element of soil pollution into gardens and are avoided by many property owners. In the UK, new oak or pine beams of the same length (2.4m) as standard railway sleepers, but not treated with dangerous chemicals, are now available specifically for garden construction. They are about twice the price of the recycled product. In some places, railroad ties have been used in the construction of homes, particularly among those with lower incomes, especially near railroad tracks, including railroad employees. They are also used as cribbing for docks and boathouses.
The Spanish artist Agustín Ibarrola has used recycled ties from Renfe in several projects.
In Germany, use of wooden railroad ties as building material (namely in gardens, houses and in all places where regular contact to human skin would be likely, in all areas frequented by children and in all areas associated with the production or handling of food in any way) has been prohibited by law since 1991 because they pose a significant risk to health and environment. From 1991 to 2002, this was regulated by the Teerölverordnung (Carbolineum By-law), and since 2002 has been regulated by the Chemikalien-Verbotsverordnung (Chemicals Prohibition By-law), §1 and Annex, Parts 10 and 17.
Rail transport is a means of transferring passengers and goods on wheeled vehicles running on rails, which are located on tracks. In contrast to road transport, where vehicles run on a prepared flat surface, rail vehicles are directionally guided by the tracks on which they run. Tracks usually consist of steel rails, installed on ties (sleepers) set in ballast, on which the rolling stock, usually fitted with metal wheels, moves. Other variations are also possible, such as slab track. This is where the rails are fastened to a concrete foundation resting on a prepared subsurface.
The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, railroad ties and ballast, plus the underlying subgrade. It enables trains to move by providing a dependable surface for their wheels to roll upon. For clarity it is often referred to as railway track or railroad track. Tracks where electric trains or electric trams run are equipped with an electrification system such as an overhead electrical power line or an additional electrified rail.
HO or H0 is a rail transport modelling scale using a 1:87 scale. It is the most popular scale of model railway in the world. The rails are spaced 16.5 mm (0.650 in) apart for modelling 1,435 mm standard gauge tracks and trains in HO.
The permanent way is the elements of railway lines: generally the pairs of rails typically laid on the sleepers or ties embedded in ballast, intended to carry the ordinary trains of a railway. It is described as permanent way because in the earlier days of railway construction, contractors often laid a temporary track to transport spoil and materials about the site; when this work was substantially completed, the temporary track was taken up and the permanent way installed.
A railgrinder is a maintenance of way vehicle or train used to restore the profile and remove irregularities from worn tracks to extend its life and to improve the ride of trains using the track. Rail grinders were developed to increase the lifespan of the tracks being serviced for rail corrugation. Rail grinding is a process that is done to stop the deformation due to use and friction on railroad tracks by removing deformations and corrosion. Railroad tracks that experience continual use are more likely to experience corrugation and overall wear. Rail grinders are used to grind the tracks when rail corrugation is present, or before corrugation begins to form on the tracks. Major freight train tracks use rail grinders for track maintenance based the interval of tonnage, rather than time. Transit systems and subways in major cities continue to use scheduled rail grinding processes to combat the corrugation common to heavily used tracks. Rail-grinding equipment may be mounted on a single self-propelled vehicle or on a dedicated rail-grinding train which, when used on an extensive network, may include crew quarters. The grinding wheels, of which there may be more than 100, are set at controlled angles to restore the track to its correct profile.
A utility pole is a column or post used to support overhead power lines and various other public utilities, such as electrical cable, fiber optic cable, and related equipment such as transformers and street lights. It can be referred to as a transmission pole, telephone pole, telecommunication pole, power pole, hydro pole, telegraph pole, or telegraph post, depending on its application. A Stobie pole is a multi-purpose pole made of two steel joists held apart by a slab of concrete in the middle, generally found in South Australia.
Track ballast forms the trackbed upon which railroad ties (sleepers) are laid. It is packed between, below, and around the ties. It is used to bear the load from the railroad ties, to facilitate drainage of water, and also to keep down vegetation that might interfere with the track structure. Ballast also holds the track in place as the trains roll over it. It typically consists of crushed stone, although other, less suitable, materials have sometimes been used such as burnt clay. The term "ballast" comes from a nautical term for the stones used to stabilize a ship.
Rail transport – means of conveyance of passengers and goods by way of wheeled vehicles running on rail tracks consisting of steel rails installed on sleepers/ties and ballast.
A backyard railroad is a privately owned, outdoor railroad, most often in miniature, but large enough for one or several persons to ride on. The rail gauge can be anything from 2 1⁄2 in to 7 1⁄2 in or more. Smaller backyard or outdoor railroads that cannot be ridden are called garden railroads. Some backyard railroads use full-size rolling stock, such as the former 3 ft narrow gauge Grizzly Flats Railroad owned by Disney animator Ward Kimball.
Tramway track is used on tramways or light rail operations. Grooved rails are often used to provide a protective flangeway in the trackwork in city streets. Like standard rail tracks, tram tracks consist of two parallel steel rails.
A tamping machine or ballast tamper is a machine used to pack the track ballast under railway tracks to make the tracks more durable. Prior to the introduction of mechanical tampers, this task was done by manual labour with the help of beaters. As well as being faster, more accurate, more efficient and less labour-intensive, tamping machines are essential for the use of concrete sleepers since they are too heavy to be lifted by hand. Whilst also available as a plain tamper with no lifting or lining function this article will focus on the multi function machines.
The rail profile is the cross sectional shape of a railway rail, perpendicular to its length.
A concrete sleeper or concrete tie is a type of railway sleeper or railroad tie made out of steel reinforced concrete.
A deck is the surface of a bridge. A structural element of its superstructure, it may be constructed of concrete, steel, open grating, or wood. Sometimes the deck is covered a railroad bed and track, asphalt concrete, or other form of pavement for ease of vehicle crossing. A concrete deck may be an integral part of the bridge structure or it may be supported with I-beams or steel girders.
A rail fastening system is a means of fixing rails to railroad ties or sleepers. The terms rail anchors, tie plates, chairs and track fasteners are used to refer to parts or all of a rail fastening system. Various types of fastening have been used over the years.
Baulk road is the name given to a type of railway track or 'rail road' that is formed using rails carried on continuous timber bearings, as opposed to the more familiar 'cross-sleeper' track that uses closely spaced sleepers or ties to give intermittent support to stronger rails.
Ladder track is a type of railway track in which the track is laid on longitudinal supports with transverse connectors holding the two rails at the correct gauge distance. Modern ladder track can be considered a development of baulk road, which supported rails on longitudinal wooden sleepers. Synonyms include longitudinal beam track.
A track renewal train is a work train that consists of many units of machinery and materials required for track renewal projects.
The Railway Tie Association (RTA) is a trade association in the railroad and rail transit industry. The purpose of the RTA is to promote the economical and environmentally sound use of wood crossties The RTA is involved in research into crosstie design and ongoing activities dealing with sound forest management, conservation of timber resources, timber processing, wood preservation, environmentally sound used tie disposal, and safety of industry workers. The Association's mission statement is: "Our mission since 1919 has been to ensure that the engineered wood crosstie system continues to evolve and improve in order to remain cost-effective and to meet the ever-changing requirements of track systems around the world."
A ballastless track or slab track is a type of railway track infrastructure in which the traditional elastic combination of ties/sleepers and ballast is replaced by a rigid construction of concrete or asphalt.
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