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Headshunt
Headshunt
Headshunt
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Platform track and run-round loop at Toyooka Station, Hyōgo, Japan, the terminus of the line from Miyazu

A headshunt (or escape track in the United States) is a short length of track provided to release locomotives at terminal platforms, or to allow shunting to take place clear of main lines.

Terminal headshunt

[edit]
Sequence at a terminal headshunt:
1. train arrives at the station
2. locomotive is detached from the train and moves into the headshunt
3. locomotive reverses and the points are switched
4. locomotive travels along the passing loop to pass the cars
5. locomotive reverses direction and the points are switched
6. locomotive couples to the opposite end of the train
7. locomotive reverses and the train departs

A 'terminal headshunt' is a short length of track that allows a locomotive to uncouple from its train, move forward, and then run back past it on a parallel track. Such headshunts are typically installed at a terminal station to allow the locomotive of an arriving train to move to the opposite end of (in railway parlance, 'run around') its train so that it can then haul the same train out of the station in the other direction (assuming, of course, that it is a locomotive equipped to run in either direction; for locomotives that only operate in one direction, a wye or turntable needs to be provided to physically turn the engine around, as well as a run-around track).

Reversing headshunt

[edit]
Main article: Pocket track
Melbourne University tram stop has three reversing headshunts in succession, between the two running lines.

Found primarily on metro systems, rapid transit light rail networks, and tramways, a 'reversing headshunt' allows certain trains or trams to change direction, even on lines with high traffic flow, whilst others continue through the station.

Shunting neck

[edit]

The term headshunt may also refer to shunting neck or 'shunt spur': a short length of track laid parallel to the main line to allow a train to shunt back into a siding or rail yard without occupying the main running-line.[citation needed]

Run round

[edit]
This section is about the track arrangement. For heat recovery system, see run around coil.
Diagram of a headshunt and run round loop

A run round loop (or run-around loop) is a track arrangement that enables a locomotive to attach to the opposite end of the train. It is commonly used to haul wagons onto a siding, or at a terminal station to prepare for a return journey.[1] This process is known as "running round a train".[2]

Although a common procedure for passenger trains when the majority of them were locomotive-hauled, the maneuver is now becoming rarer on public service railways.[citation needed] Increased use of multiple unit and push-pull passenger services avoids the requirement for dedicated track and the need for railway staff to detach and reattach the locomotive at track level.[citation needed] However, on heritage railways run-round loops are still usually more or less necessary at each end of the running line, partly because train services are usually locomotive-hauled, and partly because the run-round operation gives added interest to visitors. This practice is still very common on Intercity services in Victoria, Australia.

Runaround tracks are used in freight rail service in order to back cars into spurs or to change directions to keep the locomotive at the front of the train for transport. In this case the runaround track must be as long as the longest set of cars that would be pulled. The locomotive leaves the cars on the runaround track or the main line, goes around, and hooks up to the other end of the train. It can then reverse the cars into a spur.

Examples

[edit]

Stations which used to have run-rounds include:

  • Turntable and run round loop at Withernsea
    Turntable and run round loop at Withernsea
  • Leeds Central station showing the release crossovers
    Leeds Central station showing the release crossovers

Stations which still have run-rounds include:

No loop

[edit]

If a terminal station does not have a run-round loop trains are restricted to multiple units or Top and Tail trains.[citation needed]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Headshunt

View on Grokipedia
from Grokipedia
A headshunt is a short length of track in , primarily associated with British railway , designed to allow locomotives to be detached from trains at terminal platforms or to facilitate shunting operations clear of the main running lines. This dead-end typically connects to the head end of a yard or siding , enabling safe and efficient maneuvering without obstructing through traffic. In terminal stations, the headshunt permits a to uncouple from its , advance beyond the platform end, and then reverse onto an adjacent parallel track to run around the train consist, repositioning itself for departure in the opposite direction. In marshalling yards, it serves as a buffer track at the entrance to multiple sidings, allowing wagons or coaches to be shuffled between lines without the primary routes, thereby enhancing operational and capacity. The term is equivalent to the "escape track" used in North American contexts, where similar track configurations support freight and handling. Headshunts are commonly terminated with buffer stops to prevent overrunning and are integral to at depots, freight terminals, and heritage worldwide.

Definition and Usage

Definition

A headshunt is a short of track, typically dead-ended and terminated by a , provided to release from at terminal platforms without obstructing main lines or to enable shunting maneuvers in a . This arrangement allows the at the head of the to uncouple, proceed forward onto the headshunt, and then reverse onto an adjacent track if needed, isolating operations from through traffic. Headshunts are usually long enough to accommodate a single plus a safety margin, often 30-50 meters in depending on the system. In North American railway terminology, the equivalent is known as an "escape track," reflecting its role in providing a safe path for locomotives to detach and escape the terminal area. The term "headshunt" originates from the combination of "head," denoting the front end of a train or the leading section of a marshalling yard, and "shunt," a term for the act of switching or moving short distances. The basic track layout of a headshunt includes a stub track branching off from the main line or platform leads via points (also called switches), which direct the locomotive onto the isolated dead-end section equipped with a buffer stop to halt movement. This configuration connects directly to sidings or the station throat, ensuring clear separation from operational lines while minimizing the footprint in space-constrained terminals. A general of a simple headshunt illustrates the main line approaching points that split to the platform track and the diverging headshunt stub, with the latter ending abruptly to accommodate forward runs of detached .

Primary Purposes

Headshunts serve primarily to facilitate the release of locomotives from trains at dead-end terminals, allowing the engine to detach and reposition without blocking adjacent tracks or main lines. This function is essential in terminal stations where through running is impossible, enabling the locomotive to move forward past the train's end for subsequent at the other side. In addition to locomotive release, headshunts enable shunting operations—such as marshaling or rearranging —clear of through lines, preventing interference with mainline . By providing a dedicated short track extension beyond sidings or platforms, these arrangements support efficient wagon handling in yards and freight facilities, minimizing delays to passing trains. The use of headshunts improves by isolating shunting maneuvers from mainline movements, thereby reducing dwell times at busy stations and enhancing overall network capacity. is bolstered through this isolation, as it prevents fouling of main lines during low-speed activities, with basic signaling—such as permissive ground signals—ensuring controlled access and exit.

Types of Headshunts

Terminal Headshunt

A terminal headshunt consists of a short stub track extending beyond the end of the platform in a dead-end terminal station, connected by points that diverge from the arrival track to permit the locomotive to advance after uncoupling from the train. This design feature allows the locomotive to clear the platform and main line without fouling ongoing operations, typically incorporating a buffer stop at the far end to prevent overrunning. In historical British branch line terminals, such as those on the Caledonian Railway, the headshunt was positioned immediately beyond the platform buffers, with points set trailing to the arrival direction for safe release. The primary application of terminal headshunts is in dead-end terminals where full trains terminate, facilitating efficient release and potential repositioning for departure. This arrangement is essential in layouts without through tracks, enabling continued service without prolonged platform occupation. Modern implementations, like the proposed turnback siding at Hazelhatch & Celbridge Station in Ireland's DART+ project, integrate the headshunt with existing multi-track corridors to support high-frequency commuter services as a temporary terminus. Technical details emphasize practicality for accommodation and safety. Length requirements vary by era and scale but are generally sufficient to hold the clear of the points, historically around 23 meters (75 feet) for steam-era lines to allow basic release without full run-around. In contemporary designs, lengths can extend to 356 meters to enable extended stabling or partial train maneuvers while maintaining operational flow. considerations prioritize stability, often incorporating a slight rising profile (typically 1:400 or shallower) from the platform end to counteract gravity and prevent the uncoupled from rolling back toward the secured train; may be installed on this for added protection against . The operational sequence for locomotive release at a terminal headshunt follows a structured seven-step process to ensure safety and efficiency:
  1. The train arrives and stops at the platform, with the locomotive at the leading end.
  2. Passengers disembark, and the train is prepared for uncoupling.
  3. The locomotive is detached from the train via shunter assistance or automatic couplers.
  4. The locomotive advances slowly into the headshunt, clearing the points behind it.
  5. The train is secured using handbrakes on the leading vehicles to prevent movement.
  6. The locomotive reverses out of the headshunt, proceeds along a parallel track for run-around if required, and couples to the opposite end of the train.
  7. With brakes released, the locomotive hauls the train out of the terminal for departure.
This procedure, common in steam and early diesel eras, relies on clear signalling, such as home and shunt signals protecting the release road, to coordinate movements without conflicting with other station activities. A run-around maneuver, briefly referenced here, allows the to reposition fully but is detailed separately in associated arrangements. For visual illustration, consider historical layouts like that at Weymouth station (closed 1980s), where the engine release road paralleled the platforms between buffer stops, demonstrating the stub track's integration beyond the terminal end.

Reversing Headshunt

A reversing headshunt in metro and systems consists of short stub tracks at terminus stops, designed to enable single-unit vehicles or short consists to change direction efficiently. These stubs, often arranged in parallel, allow bi-directional vehicles to enter from the arrival track, reposition, and exit onto the departure track without fouling the main line. In the network, for example, the terminus features three such parallel shunts, each approximately 30-34 meters long, accommodating one per shunt to handle peak-hour reversals. Operationally, a train or arrives at the terminus platform, proceeds into an allocated headshunt via automatically controlled points, and the driver—facilitating driver-only operations—switches to the opposite cab to drive out in the reverse direction toward the return line. Track circuits and detectors ensure safe allocation and locking of points during this process, preventing conflicts in high-frequency urban services. This setup is particularly suited to environments where vehicles are inherently bi-directional, minimizing dwell times at ends of line. Such headshunts are commonly applied in urban and metro networks lacking space for full crossover or loop facilities, as seen in constrained city centers. For instance, in Bratislava's proposed tram extensions, a station headshunt terminus was selected for the Prievoz area to address spatial limitations while maintaining service continuity. This design minimizes the infrastructure footprint required in dense environments, historically enabling efficient operations in early electric tram systems before widespread adoption of turning loops. The layout at University's tram stop exemplifies this, with three parallel headshunts positioned adjacent to the platform, allowing simultaneous reversals for up to three vehicles during busy periods.

Shunting Neck

A shunting neck is a specialized track configuration in railway freight yards, consisting of a lead track that runs parallel to the main lines and branches into multiple sidings through a series of points or switches, serving as a buffer zone for marshaling operations without obstructing through traffic. This design allows shunting locomotives to access and maneuver wagons efficiently, with the lead track typically positioned adjacent to arrival and departure lines to facilitate seamless integration into the yard layout. At the end of the shunting neck, buffer stops are installed to halt vehicles safely and prevent overruns, ensuring operational security during intensive sorting activities. In operation, the shunting neck enables locomotives to push or pull wagons into and out of individual sidings for sorting by destination, allowing the disassembly and reassembly of freight trains clear of running lines and thereby minimizing delays to mainline services. This role is essential in maintaining yard throughput, as it supports the uncoupling of cars from incoming trains and their redistribution, which can account for 10-50% of overall freight transit time in facilities. Signaling systems, including shunting signals and permitted indicators, are integrated to control reversals and movements, ensuring safe coordination of multiple shunting operations within the neck. Shunting necks find primary application in freight classification yards, where trains are broken down and reformed, as well as in industrial sidings for loading and unloading at facilities like goods sheds or depots. They are particularly suited to flat shunting environments, where power drives all movements, but can also integrate with hump yards by providing a dedicated lead for pushing toward apex. These necks are designed with capacity for multiple vehicles, often exceeding the length of the longest expected —typically 600-700 —to accommodate extended consists during peak operations. Unlike a basic headshunt, which is a simple dead-end siding for isolated maneuvering, a shunting is extended and networked to support complex, multi-directional rearrangements, with enhanced signaling to manage concurrent reversals and . This distinction makes it indispensable for high-volume freight handling, prioritizing efficiency in marshaling over mere temporary storage.

Associated Arrangements

Run Round

A run round, also known as a run-around loop, is a track configuration consisting of a parallel siding connected to the terminal's main or platform track at both ends via crossovers, enabling a to detach from one end of the and reattach to the opposite end. This setup complements a headshunt by permitting the to circumnavigate the stationary after release, effectively switching it from the leading to the trailing position for departure. The arrangement is particularly valuable in dead-end terminals where through running is not possible, minimizing conflicts with mainline traffic. The operational sequence begins with the arriving at the platform. To perform the run round, the pulls the forward into the headshunt (if present) to clear the rear points, then uncouples and reverses onto the run round loop via the near-end crossover. It travels parallel to the , crosses over to the platform track at the far end, and proceeds to recouple to the 's opposite end. This maneuver allows the to pull the out of for the return journey, typically under signal control to ensure safety during the shunting movements. Run rounds are essential in terminals lacking continuous through tracks, facilitating efficient locomotive repositioning without the need for additional equipment like turntables. They are commonly employed in heritage railways and regional lines, where operational simplicity and space constraints favor this method over more complex alternatives. In such settings, the absence of a run round often necessitates multiple shunting staff or alternative procedures, increasing operational time and complexity. Design variations include basic setups with simple crossovers forming the parallel loop, and more integrated configurations where the run round directly adjoins the headshunt for fluid transitions between detachment and repositioning. Loop lengths are tailored to accommodate typical consists, ensuring the can fully pass and recouple without adjacent tracks; extensions may be implemented to handle longer formations in busy terminals.

Loopless Terminals

Loopless terminals facilitate efficient operations at dead-end stations by employing configurations that obviate the need for run-round loops, primarily through the use of multiple units or top-and-tail arrangements. Multiple units consist of self-propelled railcars equipped with driving cabs and traction equipment distributed throughout the consist, enabling bidirectional operation without repositioning. Top-and-tail configurations, conversely, position s at both ends of the , allowing and control from either direction to bypass traditional reversal maneuvers. Operationally, these setups permit trains to reverse direction via straightforward cab changeover in multiple units, where the crew shifts to the opposite cab, or through coordinated multiple-unit control in top-and-tail formations, eliminating the requirement for detaching and releasing locomotives. This process supports rapid platform occupancy adjustments, with turnaround times as short as 6-8 minutes in optimized signaling environments, enhancing adherence in terminus layouts. Such arrangements find prominent application in modern electrified lines and high-frequency passenger services, particularly where urban land constraints limit infrastructure expansion, as seen in systems like Japan's and the UK's proposed (but currently paused as of 2025) HS2 terminus at London Euston. They enable sustained operations at frequencies up to 18 trains per hour without expansive loop tracks, prioritizing capacity in dense metropolitan corridors. Key advantages include accelerated turnarounds that minimize dwell times and boost throughput, alongside reduced maintenance demands on non-existent loop infrastructure, thereby lowering overall operational costs. Distributed traction in multiple units further improves acceleration and energy efficiency during frequent starts and stops inherent to terminal services. The adoption of loopless terminals reflects a historical transition from steam-era reliance on run-round loops to diesel and electric multiple units post-1950s, driven by widespread dieselization in North American railways, where major conversions began in 1949 and were nearly complete by 1960, facilitating more flexible terminal designs.

Examples

Mainline Railways

In the steam era, headshunts played a crucial role in operations at terminal stations, enabling the safe release of locomotives from arriving trains without obstructing main line traffic. In freight operations, headshunts—often referred to as shunting necks—were integral to classification yards, where they provided a dedicated track section for pushing and sorting cars clear of incoming or outgoing main lines. Operational challenges with headshunts in mainline railways often center on ensuring adequate to fully clear the point beyond the switch points, preventing conflicts with main line movements. For high-speed locomotives exceeding 20 meters in , such as modern European or Japanese models, headshunts must incorporate additional buffer space—typically 10-15 meters beyond the loco—to maintain safety margins, leading to upgrades in older facilities like those in the UK where steam-era designs proved insufficient for longer diesel units. Notable incidents, including derailments from overrun due to misjudged lengths, have prompted enhancements, such as extended headshunts and improved signaling interlocks in yards worldwide.

Urban Transit Systems

In urban transit systems, headshunts are essential for managing train reversals at terminal stations where space is limited by dense city infrastructure, allowing for efficient operations without expansive loops. These compact designs are particularly prevalent in light rail and metro networks, where high passenger volumes demand quick turnaround times, often under 2-3 minutes per train. Electrification plays a key role, with overhead catenary systems in trams requiring insulated sections in headshunts to prevent arcing during reversals, while third-rail metros incorporate safety interlocks for power management during shunting maneuvers. A prominent example is the Melbourne University tram stop in , a major northern terminus on the network along . The facility features three successive reversing headshunts configured as Y-shaped stubs, each capable of holding a full D2-class articulated (approximately 30 meters long), to facilitate the high-frequency services of routes 19 (North Coburg to Flinders Street) and 59 (Airport West to Flinders Street). This layout, reconstructed in 2005, supports up to seven terminating routes daily, handling over 20,000 passengers during peak university hours by enabling parallel shunting and minimizing dwell times in the constrained 100-meter urban footprint adjacent to the campus. The overhead 600V DC electrification includes frog crossings in the headshunts to seamlessly transition trams between tracks while maintaining power continuity. In metro systems, the exemplifies the use of terminal stubs as headshunts for direction changes, avoiding the land-intensive loops common in earlier rail designs. Stations like Porte de Clignancourt on Line 4 feature stub-end platforms ending at buffers, where trains reverse direction within the stub using crossover points to switch to the return track, accommodating the network's tight 1.4-kilometer average station spacing in central . This configuration supports manual or semi-automated reversals, with drivers repositioning from one cab to the other in under 90 seconds, optimized for the 750V DC third-rail system that includes isolated sections in the stubs to ensure safe power disconnection during shunting. Such designs have been integral since the Métro's opening, enabling over 4 million daily riders across 16 lines despite subterranean space limitations. Modern automated urban systems further integrate headshunts for seamless operations, as seen in the SkyTrain network. At termini like King George station on the Expo Line, automated trains utilize turnback tracks functioning as headshunts, where the SelTrac system directs vehicles into storage sidings for reversal without human intervention, crossing over to outbound tracks via high-speed switches. This setup, part of the 79.6-kilometer fully automated light metro since 1986, handles peak frequencies of every 2 minutes by incorporating positioning for the 750V DC third-rail , with headshunts designed to fit within elevated guideway constraints amid . The integration enhances reliability, supporting over 300,000 daily boardings while reducing turnaround times to 75 seconds.

References

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