Loop Pass Adalah

Place on a railway where trains can pass each other

Passing loop
Legend
Main line Passing loop

A
passing loop
(Uk usage) or
passing siding
(Northward America) (likewise chosen a
crossing loop,
crossing place,
refuge loop
or, colloquially, a
hole) is a place on a single line railway or tramway, often located at or near a station, where trains or trams travelling in opposite directions can pass each other.^[1]
Trains/trams going in the same direction can as well overtake, provided that the signalling system allows it. A passing loop is double-concluded and connected to the master runway at both ends, though a expressionless stop siding known as a refuge siding, which is much less convenient, can be used. A like arrangement is used on the gauntlet track of cable railways and funiculars, and in passing places on single-track roads.

Ideally, the loop should be longer than all trains needing to cross at that indicate. Unless the loop is of sufficient length to be dynamic, the get-go railroad train to arrive must stop or move very slowly, while the second to arrive may pass at speed. If one train is too long for the loop information technology must wait for the opposing train to enter the loop before proceeding, taking a few minutes. Ideally, the shorter train should go far first and exit second. If both trains are too long for the loop, time-consuming “come across-sawing” (or “double saw-by”) operations are required for the trains to cross (come across Tawa railway station).^[2]

On railway systems that use platforms, especially high-level platforms, for passengers to board and disembark from trains, the platforms may exist provided on both the principal and loop tracks or possibly on but one of them.

Systems of working

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Main and loop (main track with platform)

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Legend

Legend

The main line has straight runway, while the loop line has low-speed turnouts at either end. If the station has only one platform, then information technology is unremarkably located on the main line.

If passenger trains are relatively few in number, and the likelihood of two passenger trains crossing each other low, the platform on the loop line may be omitted.

If the passenger train from one direction e’er arrives first, the platform on the loop line may also be omitted by extending the platform by the loop in that direction.

Platform road and through road (main track without platform)

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Legend

The through route has direct track, while the platform road has low-speed turnouts at either stop.

A possible advantage of this layout is that trains scheduled to pass straight through the station tin do so uninterrupted; they do not have to reduce their speed to pass through the curve. This layout is mostly used at local stations where many passenger trains exercise non terminate.

Since there is only one passenger platform, information technology is not user-friendly to cantankerous 2 passenger trains if both terminate.

This blazon of passing loop is common in Russia and mail-Soviet states. A disadvantage of the platform and through arrangement is the speed limits through the turnouts at each finish.

Up and downwardly working

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Legend

In the example layout shown, trains have the left-paw track in their direction of running. Low-speed turnouts restrict the speed in one direction. Two platform faces are needed, and they tin can exist provided either at a single island platform or 2 side platforms (as shown). Overtaking is non usually possible at this kind of up-and-downwardly loop as some of the necessary signals are absent.

Crossing loops using up-and-down working are very mutual in British exercise. For ane matter, fewer signals are required if the tracks in the station are signaled for ane direction merely; besides, at that place is less likelihood of a collision caused by signalling a train onto the runway reserved for trains in the opposing direction. In French republic, they ofttimes utilise spring switches and the speed is equally restricted in both directions.

The speed restriction in i management can be eliminated with college-speed turnouts, but this may require power performance, equally the longer and heavier high-speed turnouts may exist beyond the capability of manual lever operation.

Dead-end siding

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Fable

Refuge sidings are used at locations with gradients too steep for heavy freight trains or steam haulage to depart from conventional passing loops, or confined spaces where a passing loop cannot be built. An extra parallel siding is often built at stations on refuge sidings so that ii stopping trains can pass, and an extended catch point opposite the refuge siding may exist added so as not to interfere with passing trains.

Dynamic passing loop

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If a crossing loop is several times the length of the trains using it, and is suitably signalled, then trains proceeding in opposite directions can pass (cross) each other without having to terminate or fifty-fifty slow down. This greatly reduces the time lost by the start train to get in at the crossing loop for the opposing train to become past. This system is referred to every bit a dynamic loop.

Overlaps and catch points

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Some railways fit take hold of points at the ends of crossing loops so that if a railroad train overruns the loop, it is derailed rather than collide with an opposing train.

Since the available infinite for crossing loops is ordinarily limited, they exercise non normally take an overlap (safety margin) between the starting signals and the cease of the double line. In Commonwealth of australia, the Australian Rail Track Corporation (ARTC) policy provides for overlaps of most 500 k and 200 thou respectively in an effort to avert derailment or collision.

Automatic operation

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Many crossing loops are designed to operate automatically in an unattended mode. Such loops may be track-circuited with home signals cleared by the approaching train. Some loops accept the points in and out of the loop operated manually, albeit more recent examples have then-called self-restoring switches that allow trains to exit a loop without needing to change the points.

Other forms of remote operation included centralized traffic control, in which a railroad train controller changes points and signals from a remote role; and driver-operated points, which enable train crews to utilize a radio system to set up the points from a distance.

Gradients

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The blueprint of crossing loops may have to be modified where there are severe gradients that brand it difficult for a train to restart from a stationary position, or where the terrain is unsuitable for a normal loop.

A crossing loop on steep gradient may have grab points on the downhill end to reduce the affect of runaways.

Train length

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Since central operation of the points and signals from a single signal box is convenient, and since there are practical limits for the distance to these points and signals, crossing loops tin accept a organisation-wide effect on train sizes.

Line capacity

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Line chapters is partly adamant by the distance betwixt individual crossing loops. Ideally these should be located at inverse-integer intervals along the track past travel fourth dimension. The longest department betwixt successive crossing loops will, like the weakest link in a chain, determine the overall line capacity.

Short loops

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Long and short trains can cantankerous at a curt loop if the long train arrives second but leaves first.

It is best if all crossing loops are longer than the longest train. Two long trains can cross at a short loop using a slow so-called run into-saw process, which wastes fourth dimension.

Correct- and left-paw traffic

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Countries more often than not have a principle on which side trains shall meet, either on the left or on the right, generally the aforementioned for the whole country. Merely this is generally valid just on double track. On passing loops this principle is not necessarily used. Often the train that shall not stop uses the straight runway. See also Correct- and left-hand traffic.

Gallery

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• 

  Passing sidings in Northward America can be very long. This one in Bolton, Ontario – the track on the right – measures some 3.5 km.

Accidents at crossing loops

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Engagement	Incident	Location	Details
1900	Casey Jones	Vaughan, Mississippi, USA	The legendary railroad train driver (U.Southward.: engineer) John Luther “Casey” Jones was killed in an accident involving trains too long to cross at a passing loop. The trains trying to cross were occupying both the main and loop tracks, and in addition, the train doing the meet-saw was standing outside station limits. Jones was traveling fast in guild to make up lost time, and could not stop in time to avoid a standoff. He was able to slow his railroad train from an estimated 75 mph (121 km/h) to an estimated 35 mph (56 km/h) at the time of standoff; none of the passengers on Jones’south train was seriously injured, and Jones was the simply fatality.
1914	Exeter crossing loop collision	Exeter, New South Wales, Commonwealth of australia	occurred at Exeter railway station in fog: i train too long for loop; line duplicated soon after
1917	Ciurea rail disaster	Ciurea station, Romania
1947	Dugald rail accident	Dugald, Manitoba, Canada
1963	Geurie crossing loop collision	Geurie, New S Wales, Commonwealth of australia	railroad train in loop standing foul of master line, causing collision
1969	Violet Boondocks	Violet Town, Victoria, Australia	Betoken passed at danger after driver dies from middle attack
1996	Hines Hill train collision	Hines Hill, Western Australia	commuter appears to have misjudged distance to starting betoken
1999	Zanthus train collision	Zanthus, Western Commonwealth of australia	co-driver operated loop points prematurely
2006	Ngungumbane train collision	Zimbabwe

Other names and types

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• crossing loop
  or
  crossing place
• passing siding
  (Usa)
• refuge loop
  – used on double track lines
• A run-effectually loop enables a locomotive to modify ends when a train has reached a terminus station.
• Spirals are sometimes called
  loops.
• Balloon loops are sometimes called
  loops.

See also

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• Glossary of Due north American railway terminology
• Lists of rail accidents
• Refuge siding
• Siding
• Train meet

References

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