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74-681: The Hitachi Rail Italy Driverless Metro is a class of driverless electric multiple units and corresponding signaling system. Manufactured by Hitachi Rail Italy (formerly AnsaldoBreda) and Hitachi Rail STS (former name Ansaldo STS) in Italy, it is or will be used on the Copenhagen Metro , a people mover at Princess Nourah Bint Abdul Rahman University , the Brescia Metro , the Thessaloniki Metro , lines 4 and 5 of

148-483: A 750 V DC   third rail (except in Rome where it is 1,500 V DC overhead line ). The systems are fully automated, consisting of automatic train protection (ATP), automatic train operation (ATO) and automatic train supervision . The rolling stock uses standardized car bodies, articulated together. The number of cars varies across the different systems where they are used. The trains used on

222-529: A headway of between two and twenty minutes, including an all-night service. In April 2008, the Copenhagen Metro won the award at MetroRail 2008 for the world's best metro. Skyline is a 10.8 mi (17.4 km) elevated rail line, planned to extend to 18.9 mi (30.4 km), which will connect the city of Honolulu on the island of Oʻahu in Hawaiʻi with outlying suburbs. The first section of

296-436: A railway junction or where a spur or siding branches off. The most common type of switch consists of a pair of linked tapering rails, known as points ( switch rails or point blades ), lying between the diverging outer rails (the stock rails ). These points can be moved laterally into one of two positions to direct a train coming from the point blades toward the straight path or the diverging path. A train moving from

370-638: A barrier between the metal surfaces to prevent ice from forming between them (i.e. having frozen together by ice). Such approaches however, may not always be effective for extreme climates since these chemicals will be washed away over time, especially for heavily thrown switches that experience hundreds of throws daily. Heating alone may not always be enough to keep switches functioning under snowy conditions. Wet snow conditions, which generate particularly sticky snow and whiteout conditions, may occur at temperatures just below freezing, causing chunks of ice to accumulate on trains. When trains traverse over some switches,

444-426: A connection between two or more parallel tracks, allowing a train to switch between them. In many cases, where a switch is supplied to leave a track, a second is supplied to allow the train to reenter the track some distance down the line; this allows the track to serve as a siding, allowing a train to get off the track to allow traffic to pass (this siding can either be a dedicated short length of track, or formed from

518-601: A crossover can be used either to detour "wrong-rail" around an obstruction or to reverse direction. A crossover can also join two tracks of the same direction, possibly a pair of local and express tracks, and allow trains to switch from one to the other. On a crowded system, routine use of crossovers (or switches in general) will reduce throughput, as use of the switch blocks multiple tracks. For this reason, on some high-capacity rapid transit systems, crossovers between local and express tracks are not used during normal rush hour service, and service patterns are planned around use of

592-489: A fully automated computer system, located at the control and maintenance center. The automatic train control (ATC) consists of three subsystems: automatic train protection (ATP), automatic train operation (ATO) and automatic train supervision (ATS). The ATP is responsible for managing the trains' speed, ensuring that doors are closed before departure and that switches are correctly set. The system uses fixed block signaling , except around stations, where moving block signaling

666-886: A power output of 105 and 128 kW (141 and 172 hp), giving each train a power output of 630 or 764 kW (845 or 1,025 hp). In each car, the two motors are fed by the car's own insulated-gate bipolar transistor . The trains are powered by 750 V bottom contact third rail in most applications, although in Honolulu the same voltage is used but the third rail instead top contact, while Rome uses 1500 V overhead wires. The trains' top speeds are 80 to 105 km/h (50 to 65 mph), with an acceleration and deceleration capacity of 1.3 m/s/s (2.9 mph/s). Trains are fully compatible with platform screen doors , which are found at all stations in Brescia, Rome and Milan, Copenhagen, Honolulu, and Thessaloniki. The systems are controlled by

740-427: A regular crossing. Double outside slip switches are only used in rare, specific cases. A crossover is a pair of switches that connects two parallel rail tracks , allowing a train on one track to cross over to the other. Like the switches themselves, crossovers can be described as either facing or trailing . When two crossovers are present in opposite directions, one after the other, the four-switch configuration

814-442: A section of a second, continuous, parallel line), and also allows trains coming from either direction to switch between lines; otherwise, the only way for a train coming from the opposite direction to use a switch would be to stop, and reverse through the switch onto the other line, and then continue forwards (or stop, if it is being used as a siding). A straight track is not always present; for example, both tracks may curve, one to

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888-417: A switch in this direction is known as a trailing-point movement and switches that allow this type of movement without damage to the mechanism are called trailable switches . A switch generally has a straight "through" track (such as the main-line) and a diverging route. The handedness of the installation is described by the side that the diverging track leaves. Right-hand switches have a diverging path to

962-490: A train could potentially split the points (end up going down both tracks) if the points were to move underneath the train. During trailing moves, the wheels of a train will force the points into the correct position if they attempt to move, although this may cause considerable damage. This act is known as a "run through". In the United Kingdom, FPLs were common from an early date, due to laws being passed which forced

1036-417: Is a lever and accompanying linkages to align the points of a switch by hand. The lever and its accompanying hardware is usually mounted to a pair of long ties (sleepers) that extend from the switch at the points. They are often used in a place of a switch motor on less frequently used switches. In some places, the lever may be some distance from the points, as part of a lever frame or ground frame. To prevent

1110-425: Is a short piece of rail placed alongside the main (stock) rail opposite the crossing. These ensure that the wheels follow the appropriate flangeway through the frog and that the train does not derail. Check rails are often used on very sharp curves, even where there are no switches. A switch motor or switch machine (point motor or point machine) is an electric, hydraulic or pneumatic mechanism that aligns

1184-410: Is called a double crossover . If the crossovers in different directions overlap to form an ×, it is dubbed a scissors crossover , scissors crossing , or just scissors ; or, due to the diamond in the center, a diamond crossover . This makes for a very compact track layout at the expense of using a level junction . In a setup where each of the two tracks normally carries trains of only one direction,

1258-433: Is measured as the number of units of length for a single unit of separation. In North America this is generally referred to as a switch's "number". For example, on a "number 12" switch, the rails are one unit apart at a distance of twelve units from the center of the frog. In the United Kingdom points and crossings using chaired bullhead rail would be referred to using a letter and number combination. The letter would define

1332-453: Is planned to open by 2027. The first stage of 5.6 kilometres (3.5 mi) was estimated to cost €500 million. Milan Metro's fourth line is currently under construction and will run from Linate Airport to San Cristoforo. It will be 15 km (9.3 mi) long with 21 stations. The first section, running from Linate to Dateo, opened on 26 November 2022, while the completion of the line is expected to be in 2024. An 11·5 km metro serving

1406-425: Is possible to modify the simpler types of switch to allow trains to pass at high speed. More complicated switch systems, such as double slips, are restricted to low-speed operation. On European high-speed lines, it is not uncommon to find switches where a speed of 200 km/h (124 mph) or more is allowed on the diverging branch. Switches were passed over at a speed of 560 km/h (348 mph) (straight) during

1480-438: Is scheduled to open in phases from 2023, at a cost of €1.57 billion ($ 1.77 billion). The 14.28 km (8.87 mi) system will feature 18 stations in 2021. 33 driverless AnsaldoBreda units will be put to operation on the two lines. Those will be articulated in 4 sections with a capacity of 466 passengers (96 seated and 370 standing). Electric multiple unit EMUs are popular on commuter, and suburban rail networks around

1554-416: Is used. The system has been designed and built by Union Switch & Signal . The ATO is the autopilot that drives the trains in line with a pre-defined schedule, ensures that the train stop at stations and operates the doors. The ATS monitors all components of the network, including the rails and all trains on the system, and displays a live schematic at the control center. The ATC is designed so that only

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1628-589: The Budd Metroliner . EMUs powered by fuel cells are under development. If successful, this would avoid the need for an overhead line or third rail . An example is Alstom ’s hydrogen -powered Coradia iLint . The term hydrail has been coined for hydrogen-powered rail vehicles. Many battery electric multiple units are in operation around the world, with the take up being strong. Many are bi-modal taking energy from onboard battery banks and line pickups such as overhead wires or third rail. In most cases

1702-721: The Milan Metro , Line C of the Rome Metro , Skyline in Honolulu , and the Circular line of the New Taipei Metro . The first system to use this class of driverless electric multiple units was the Copenhagen Metro which was opened in 2002. The rolling stock consists of two to six articulated cars which operate on standard gauge . Each car has a power output of 210 or 256 kilowatts (282 or 343 hp), fed from

1776-622: The South Side Elevated Railroad (now part of the Chicago 'L' ) in 1897. In 1895, derived from his company's invention and production of direct current elevator control systems, Frank Sprague invented a multiple unit controller for electric train operation. This accelerated the construction of electric traction railways and trolley systems worldwide. Each car of the train has its own traction motors: by means of motor control relays in each car energized by train-line wires from

1850-558: The ATP is safety-critical, and will halt trains if the other systems have faults. Other aspects of the system, such a power supply, ventilation, security alarms, cameras and pumps, are controlled by a system called "control, regulating and surveillance". The most common repairs are the grinding of the wheels; more complicated repairs are made by replacing entire components that are sent to the manufacturer. By having components in reserve, trains can have shorter maintenance times. The center also has

1924-495: The French world speed run of April 2007. The US Federal Railroad Administration has published the speed limits for higher-speed turnouts with No.  26.5 turnout that has speed limit of 60 miles per hour (97 km/h) and No.  32.7 with speed limit of 80 miles per hour (129 km/h). Under cold weather conditions, snow and ice can prevent the proper movement of switch or frog point rails, essentially inhibiting

1998-662: The Honolulu Skyline units which are 10 ft (3,048 mm) wide to comply with Federal Railroad Administration regulations. The units vary from 3.4 to 3.85 m (11 ft 1 + 7 ⁄ 8  in to 12 ft 7 + 5 ⁄ 8  in) tall. Each car has two doors on each side, which are 1.3 m (4 ft 3 + 1 ⁄ 8  in) wide and 1.945 m (6 ft 4 + 5 ⁄ 8  in) tall. The vehicles are designed by Giugiaro Design . The three and four-car trains have six three-phase asynchronous motors per train, with each motor giving

2072-652: The Metro. The Copenhagen Metro, Denmark, consists of four lines, M1 , M2 , M3 and M4 that run 35.9 kilometers (22.3 mi) serving 37 stations. The system opened in 2002 and was expanded in 2019 with further expansion being planned and evaluated. The first lines connects the city center to the areas of Frederiksberg and Amager , and Copenhagen Airport . The next extension, the City Circle Line opened on 29 September 2019. Metroselskabet took delivery of 34 three-car units between 2002 and 2007, and operates with

2146-508: The Princess Nora Bint Abdulrahman University on the outskirts of Riyadh opened in 2012. Rome Metro 's Line C is 25.5 km (15.8 mi) long, of which 17.6 km (10.9 mi) are underground. Metropolitana di Roma has ordered thirty six-car units, which are 20 centimeters (7.9 in) wider than the other systems' vehicles, and capable of carrying 1,200 passengers per train. Average speed on

2220-566: The Princess Nora bint Abdul Rahman University system are 2-car units. For the other systems, the units vary between three and six cars, making the trains from 39 to 109 m (127 ft 11 + 3 ⁄ 8  in to 357 ft 7 + 3 ⁄ 8  in) long. They are 2.65 m (8 ft 8 + 3 ⁄ 8  in) wide, except the Rome Metro units which are 2.85 meters (9 ft 4 + 1 ⁄ 4  in) wide, and

2294-630: The UK and most other Commonwealth countries, the term points refers to the entire mechanism. In professional parlance, the term refers only to the movable rails and the entire mechanism is named turnout or points and crossings . Turnout and switch are terms used in North America in all contexts. In some cases, the switch blades can be heat treated for improvement of their service life. There are different kinds of heat treatment processes such as edge hardening or complete hardening. The cross-section of

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2368-448: The ancillary equipment required per set) while allowing all cars to be powered, unlike a motor-trailer combination. Each car has only one control cab, located at the outer end of the pair, saving space and expense over a cab at both ends of each car. Disadvantages include a loss of operational flexibility, as trains must be multiples of two cars, and a failure on a single car could force removing both it and its partner from service. Some of

2442-694: The arrangement may also be called a double switch , or more colloquially, a puzzle switch . The Great Western Railway in the United Kingdom used the term double compound points , and the switch is also known as a double compound in Victoria (Australia) . In Italian, the term for a double switch is deviatoio inglese , which means English switch . Likewise, it is called Engels(e) Wissel in Dutch and, occasionally, Engländer ("english one", literally "Englishman") in German. A single slip switch works on

2516-402: The batteries are charged via the electric pickup when operating on electric mode. EMUs, when compared with electric locomotives , offer: Electric locomotives, when compared to EMUs, offer: Railroad switch A railroad switch ( AE ), turnout , or [ set of ] points ( CE ) is a mechanical installation enabling railway trains to be guided from one track to another, such as at

2590-461: The case. A mechanism is provided to move the points from one position to the other ( change the points ). Historically, this would require a lever to be moved by a human operator, and some switches are still controlled this way. However, most are now operated by a remotely controlled actuator called a point machine ; this may employ an electric motor or a pneumatic or hydraulic actuator . This both allows for remote control and monitoring and for

2664-431: The crossing are often connected to move in unison, so the crossing can be worked by just two levers or point motors. This gives the same functionality of two points placed end to end. These compact (albeit complex) switches usually are found only in locations where space is limited, such as station throats (i.e. approaches) where a few main lines spread out to reach any of numerous platform tracks. In North American English,

2738-402: The diamond instead of inside. An advantage over an inside slip switch is that trains can pass the slips with higher speeds. A disadvantage over an inside slip switch is that they are longer and need more space. An outside slip switch can be so long that its slips do not overlap at all, as in the example pictured. In such a case a single, outside slip switch is the same as two regular switches and

2812-404: The earlier type of interlocking. A railroad car 's wheels are primarily guided along the tracks by coning of the wheels, rather than relying on the flanges on the insides of the wheels. When the wheels reach the switch, the wheels are guided along the route determined by which of the two points is connected to the track facing the switch. In the illustration, if the left point is connected,

2886-441: The extra equipment needed to transmit electric power to the train can be difficult. Multiple unit train control was first used in the 1890s. The Liverpool Overhead Railway opened in 1893 with two-car electric multiple units, controllers in cabs at both ends directly controlling the traction current to motors on both cars. The multiple unit traction control system was developed by Frank Sprague and first applied and tested on

2960-481: The following corresponding radii: Switches are necessary for the operation of a railway, but they do pose a number of risks: Switch-related accidents caused by one or more of these risks have occurred, including: The switch rails or points ( point blades ) are the movable rails which guide the wheels towards either the straight or the diverging track. They are tapered, except on stub switches in industrial sidings, which have square ends. In popular parlance in

3034-418: The frequency of trains, or applying anti-icing chemicals such as ethylene glycol to the trains. The divergence and length of a switch is determined by the angle of the frog (the point in the switch where two rails cross, see below) and the angle or curvature of the switch blades. The length and placement of the other components are determined from this using established formulas and standards. This divergence

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3108-399: The front car all of the traction motors in the train are controlled in unison. The cars that form a complete EMU set can usually be separated by function into four types: power car, motor car, driving car, and trailer car. Each car can have more than one function, such as a motor-driving car or power-driving car. On third rail systems, the outer vehicles usually carry the pick up shoes with

3182-494: The left and one to the right (such as for a wye switch ), or both tracks may curve, with differing radii , while still in the same direction. Switches consume a relatively high proportion of a railway maintenance budget. Simple single-bladed switches were used on early wooden railways to move wagons between tracks. As iron-railed plateways became more common in the eighteenth century, cast iron components were made to build switches with check rails. In 1797, John Curr described

3256-408: The left wheel will be guided along the rail of that point, and the train will diverge to the right. If the right point is connected, the right wheel's flange will be guided along the rail of that point, and the train will continue along the straight track. Only one of the points may be connected to the facing track at any time; the two points are mechanically locked together to ensure that this is always

3330-466: The length (and hence the radius) of the switch blades and the number would define the angle of the crossing (frog). Thus an A7 turnout would be very short and likely only to be found in tight places like dockyards whereas an E12 would be found as a fairly high speed turnout on a mainline. On the London, Midland and Scottish Railway , switch curvatures were specified from A (sharpest) to F (shallowest), with

3404-507: The line opened on 30 June 2023, with the entire 19-station route to be completed by 2031. The Line 2 of Lima Metro and a branch of Line 4, which will connect the city of east to west in the first case and the portion of line 4 linking the Jorge Chavez International Airport with the line 2, is currently under construction. The line will be built in two phases, the first of which is scheduled to open in 2017 and

3478-874: The more famous electric multiple units in the world are high-speed trains: the Italian Pendolino and Frecciarossa 1000 , Shinkansen in Japan, the China Railway High-speed in China, ICE 3 in Germany, and the British Rail class 395 Javelin. The retired New York–Washington Metroliner service, first operated by the Pennsylvania Railroad and later by Amtrak , also featured high-speed electric multiple-unit cars, known as

3552-624: The motor vehicles receiving the current via intra-unit connections . Many modern two-car EMU sets are set up as twin or "married pair" units. While both units in a married pair are typically driving motors, the ancillary equipment (air compressor and tanks, batteries and charging equipment, traction power and control equipment, etc.) are shared between the two cars in the set. Since neither car can operate without its "partner", such sets are permanently coupled and can only be split at maintenance facilities. Advantages of married pair units include weight and cost savings over single-unit cars (due to halving

3626-407: The movable switch blades were connected to the fixed closure rails with loose joints, but since steel is somewhat flexible it is possible to obviate this looseness by thinning a short section of the rail's bottom itself. This can be called a heelless switch . Turnouts were originally built with straight switch blades, which ended at the pointed end with a sharp angle. These switches cause a bump when

3700-407: The narrow end toward the point blades (i.e. it will be directed to one of the two paths, depending on the position of the points) is said to be executing a facing-point movement . For many types of switch, a train coming from either of the converging directions will pass through the switch regardless of the position of the points, as the vehicle's wheels will force the points to move. Passage through

3774-405: The other, alternatively to going straight across. A train approaching the arrangement may leave by either of the two tracks on the opposite side of the crossing. To reach the third possible exit, the train must change tracks on the slip and then reverse. The arrangement gives the possibility of setting four routes, but because only one route can be traversed at a time, the four blades at each end of

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3848-600: The points with one of the possible routes. The motor is usually controlled remotely by the dispatcher (signaller in the UK). The switch motor also includes electrical contacts to detect that the switch has completely set and locked. If the switch fails to do this, the governing signal is kept at red (stop). There is also usually some kind of manual handle for operating the switch in emergencies, such as power failures, or for maintenance purposes. A patent by W. B. Purvis dates from 1897. A switch stand ( points lever or ground throw )

3922-581: The proper operation of railroad switches. Historically, railway companies have employees keep their railroad switches clear of snow and ice by sweeping the snow away using switch brooms (Basically wire brooms with a chisel attached onto the opposite end of the broom – quite similar to ice scrapers used today), or gas torches for melting ice and snow. Such operation are still used in some countries, especially for branch routes with only limited traffic (e.g. seasonal lines). Modern switches for heavily trafficked lines are typically equipped with switch heaters installed in

3996-476: The proper position without damage. Examples include variable switches, spring switches, and weighted switches. If the points are rigidly connected to the switch control mechanism, the control mechanism's linkages may be bent, requiring repair before the switch is again usable. For this reason, switches are normally set to the proper position before performing a trailing-point movement. Generally, switches are designed to be safely traversed at low speed. However, it

4070-410: The provision of FPLs for any routes traveled by passenger trains – it was, and still is, illegal for a passenger train to make a facing move over points without them being locked, either by a point lock, or temporarily clamped in one position or another. Joints are used where the moving points meet the fixed rails of the switch. They allow the points to hinge easily between their positions. Originally

4144-443: The right of the straight track, when coming from the point blades, and a left-handed switch has the diverging track leaving to the opposite side. In many cases, such as rail yards, many switches can be found in a short section of track, sometimes with switches going both to the right and left (although it is better to keep these separated as much as feasible). Sometimes a switch merely divides one track into two; at others, it serves as

4218-421: The same principle as a double slip, but provides for only one switching possibility. Trains approaching on one of the two crossing tracks can either continue over the crossing, or switch tracks to the other line. However, trains from the other track can only continue over the crossing, and cannot switch tracks. This is normally used to allow access to sidings and improve safety by avoiding having switch blades facing

4292-414: The second in 2020. The total of the 2 lines will cost US$ 5,346,000. The Milan Metro 's Line 5 first section between Bignami and the interconnection with M3 at Zara opened on 10 February 2013. The second stage opened on 1 March 2014, and runs from Zara to Porta Garibaldi station. The third opened in 2015, and runs from Garibaldi to San Siro stadium. The fourth section will run from Bignami to Monza, and it

4366-451: The shock, vibration, possibly in combination with slight heating caused by braking or a city microclimate, may cause the chunks of ice to fall off, jamming the switches. The heaters need time to melt the ice, so if service frequency is extremely high, there may not be enough time for the ice to melt before the next train arrives, which will then result in service disruptions. Possible solutions include installing higher capacity heaters, reducing

4440-460: The switch blades also influences performance. New tangential blades perform better than old-style blades. The crossing is the component that enables passage of wheels on either route through the turnout. It can be assembled out of several appropriately cut and bent pieces of rail or can be a single casting of manganese steel. On lines with heavy use, the casting may be treated with explosive shock hardening to increase service life. A guard rail

4514-423: The switch rails being about 25 mm (0.98 in) less high, and stockier in the middle. Apart from the standard right-hand and left-hand switches, switches commonly come in various combinations of configurations. A double slip switch ( double slip ) is a narrow-angled diagonal flat crossing of two lines combined with four pairs of points in such a way as to allow vehicles to change from one straight track to

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4588-636: The system is 35 km/h (21.7 mph), with the headway varying from three to twelve minutes. The Yellow line or the Circular line of the New Taipei Metro , Taiwan, will serve as a cross-link between existing lines. The 49 km (30.4 mi) system will feature 42 or 41 stations. The 15.4 km (9.6 mi) phase 1 has 14 stations and was completed in January 2020. The Taipei Rapid Transit Corporation purchased 17 trainsets for this phase. Construction on Greece's second metro system began in 2006 and

4662-424: The system that he developed which used a single iron blade, hinged on a vertical pin that was tapered to lie against the plateway. By 1808, Curr's basic design was in common use. The use of a sprung rail, giving a smooth transition, was patented by Charles Fox in 1838. Prior to the widespread availability of electricity , switches at heavily traveled junctions were operated from a signal box constructed near

4736-453: The system's work trains, including a diesel locomotive that can fetch broken trains. At any time, there are four people working at the control center. Two monitor the ATC system, one monitors passenger information, while the last is responsible for secondary systems, such as power supply. In case of technical problems, there is always a team of technicians who can be sent to perform repairs. Although

4810-405: The tampering of switches by outside means, these switches are locked when not in use. A facing point lock ( FPL ), or point lock , is a device which, as the name implies, locks a set of points in position, as well as mechanically proving that they are in the correct position. The facing point part of the name refers to the fact that they prevent movement of the points during facing moves, where

4884-579: The tracks through an elaborate system of rods and levers . The levers were also used to control railway signals to control the movement of trains over the points. Eventually, mechanical systems known as interlockings were introduced to make sure that a signal could only be set to allow a train to proceed over points when it was safe to do so. Purely mechanical interlockings were eventually developed into integrated systems with electric control. On some low-traffic branch lines, in self-contained marshalling yards , or on heritage railways , switches may still have

4958-500: The train traverses in the turnout direction. The switch blades could be made with a curved point which meets the stockrail at a tangent, causing less of a bump, but the disadvantage is that the metal at the point is thin and necessarily weak. A solution to these conflicting requirements was found in the 1920s on the German Reichsbahn. The first step was to have different rail profile for the stock rails and switch rails, with

5032-514: The trains are not equipped with drivers, there can be stewards that help passengers, perform ticket controls and assist in emergency situations. The Brescia Metro is a system which opened in March 2013 in Brescia , Italy. The 18 km (11.2 mi) system was built in three stages and has 17 stations. The system features a 90-second headway. ASM Brescia ordered 18 trains which are now being used on

5106-406: The use of stiffer, strong switches that would be too difficult to move by hand, yet allow for higher speeds. In a trailing-point movement (running through the switch in the wrong direction while they are set to turn off the track), the flanges on the wheels will force the points to the proper position. This is sometimes known as running through the switch . Some switches are designed to be forced to

5180-414: The usual direction of traffic. To reach the sidings from what would be a facing direction, trains must continue over the crossing, then reverse along the curved route (usually onto the other line of a double track) and can then move forward over the crossing into the siding. An outside slip switch is similar to the double or single slip switches described above, except that the switch blades are outside of

5254-404: The usually flying junctions at each end of the local-express line. A stub switch lacks the tapered points (point blades) of a typical switch. Instead, both the movable rails and the ends of the rails of the diverging routes have their ends cut off square. The switch mechanism aligns the movable rails with the rails of one of the diverging routes. In 19th century US railroad use, the stub switch

5328-535: The vicinity of their point rails so that the point rails will not be frozen onto the stock rail and can no longer move. These heaters may take the form of electric heating elements or gas burners mounted on the rail, a lineside burner blowing hot air through ducts, or other innovative methods (e.g. geothermal heat sink, etc.) to keep the point & stock rails above freezing temperatures. Where gas or electric heaters cannot be used due to logistic or economic constraints, anti-icing chemicals can sometimes be applied to create

5402-459: The world due to their fast acceleration and pollution-free operation, and are used on most rapid-transit systems. Being quieter than diesel multiple units (DMUs) and locomotive -hauled trains, EMUs can operate later at night and more frequently without disturbing nearby residents. In addition, tunnel design for EMU trains is simpler as no provision is needed for exhausting fumes, although retrofitting existing limited-clearance tunnels to accommodate

5476-482: Was typically used in conjunction with a harp switch stand . The rails leading up to a stub switch are not secured to the sleepers for several feet, and rail alignment across the gap is not positively enforced. Stub switches also require some flexibility in the rails (meaning lighter rails), or an extra joint at which they hinge. Therefore, these switches cannot be traversed at high speed or by heavy traffic and so are not suitable for main line use. A further disadvantage

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