Slippery rail

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A Network Rail Railhead Treatment Train uses a high-pressure water jet to remove compressed leaf mulch from the rails in the United Kingdom. Taunton 66148 66116 railhead treatment train.jpg
A Network Rail Railhead Treatment Train uses a high-pressure water jet to remove compressed leaf mulch from the rails in the United Kingdom.

Slippery rail, or low railhead adhesion, [1] [2] [3] is a condition of railways (railroads) where contamination of the railhead reduces the traction between the wheel and the rail. This can lead to wheelslip when the train is taking power, and wheelslide when the train is braking. One common cause of contamination is fallen leaves that adhere to the railhead (top surface) of railway tracks. The condition results in significant reduction in friction between train wheels and rails, and in extreme cases can render the track temporarily unusable. In Britain, the situation is colloquially referred to as "leaves on the line".

Contents

Low adhesion caused by weather

Railhead contamination caused by weather conditions can occur at any time of year.

The leaf fall season causes the most disruption to rail operations. [4] In heavily deciduous forested areas like the American Mid-Atlantic states, New England, many parts of Europe including the UK, and Southern Ontario, Canada, the problem can arise. Where the leaves fall onto a railway route, some collect on the railhead and are then heavily compressed by trains into a slippery low-friction coating on the rail and on the wheel treads. If the climate is damp, the wet leaves adhere to the rail very effectively. The draft caused by the passage of the train causes nearby leaves to be caught up in air currents, and more leaves are deposited on the railhead. The build-up of this material is incremental, and it is hard enough not to be quickly worn away by the ordinary passage of trains. [5] [6]

Winter can provide problems of low adhesion when snow and ice are deposited on running lines. [4] Just as with road vehicles, black ice can cause trains to encounter difficulty when starting away, or can initiate wheel slide during braking.

Even summer can have its problems. A light rain shower following a long period of dry weather can sometimes cause similar low adhesion conditions to those of leaf fall contamination. [7] As the water dries it mixes with oxide debris and creates a paste that separates the wheel and rail reducing adhesion. [8] [9] Although the effect is only short term, its unpredictability can cause a significant incident to occur. A morning dew can have the same effect. [7] [10] [11]

Disc brakes add to the problem

Before about 1960, most railway vehicles used brake shoes to stop the train by applying pressure on the wheel treads. Since then, disc brakes have increasingly been used, which means that cleaning the compressed leaf material from the wheel tread by abrasion no longer occurs. [12]

Lack of lineside maintenance

A report by England's Commissioners of Railways of May 1851 noted that an accident was caused when a small locomotive hauling a heavy train was unable to find purchase on the rail because by the dirty state of the track ballast. It was the duty of the fireman when necessary to dismount from the locomotive and gather track ballast to throw under the driving wheels to maintain grip, but in this particular instance dirty ballast, containing a proportion of earth, failed to achieve the required outcome. [13]

In the steam locomotive era, trees and other lineside vegetation would be regularly cut back to reduce the risk of their being ignited by sparks from the locomotive. As the railways ceased to use steam traction, this maintenance was allowed to lapse, and the resulting extra growth increases the supply of leaves thereby exacerbating the problem. [14]

Low adhesion caused by crushed insects

There are many substances which can cause low adhesion when they are deposited on the railhead. In Victoria, Australia, train wheels crushing plagues of introduced Portuguese millipedes which were crossing the tracks, caused passenger rail operator V/Line to be penalised more than $700,000 for cancellations and poor punctuality in one quarter of 2001. [15] In 2009, railway tracks at Tallarook in central Victoria were also affected by a Portuguese millipede plague, causing several trains to be cancelled. [16] The crushing of Portuguese millipedes is suspected to have caused a crash between two trains at Clarkson near Perth, Western Australia, in September 2013. [16]

Slippery rails caused by caterpillars were reported in Queensland in 1938. [17] Crushed locusts affected train operations on the Otavi Mining and Railway Company in South-West Africa (modern Namibia) in 1924.

Effects

Flat spot Flachstelle.JPG
Flat spot

The loss of friction between wheels and rail results in loss of tractive force: the wheels begin to spin, and in some instances the train is unable to move. In braking, substantial loss of friction results in reduced braking force. Braking distances are considerably longer, and in extreme cases the wheels may even lock up, causing the train to slide. Modern locomotives and multiple units are equipped with Wheel slide protection to counter slippery rail conditions. Locked wheels can self-grind flat spots on the steel tyres, especially if the wheels are still sliding when arriving at a non-greasy section of rail, e.g. one that has previously been sanded. This causes the wheels to go out of profile (known colloquially as 'wheel flats'), [18] which subsequently leads to severe vibration and the need for the wheels to be re-profiled or re-tyred at great expense.

In extreme cases, the build-up of leaf material can electrically insulate the wheels from the rails, resulting in a failure of signalling equipment to detect the presence of the train. [4] Where the problem is severe, Track Circuit Actuators [19] fitted to trains can help alleviate the problem.

In the United Kingdom, it was estimated that the poor adhesion problems cost the rail industry GBP 355 million (USD 449 million) a year. [20]

Mitigation measures

Railhead treatment

A Long Island Rail Road work train pressure-washes the rail before applying a traction gel. LIRR applying sandite 1.jpg
A Long Island Rail Road work train pressure-washes the rail before applying a traction gel.

Treatment measures generally involve some system to jet or blast the accumulated deposit away, or to coat it with a high-friction material. Blasting is usually carried out with water jets, often in combination with mechanical scrubbing apparatus. The coating method usually involves depositing sand in a paste on to the rail; as the sand may exacerbate the risk of unwanted insulation, the sand mix sometimes contains metal particles. The coating is applied from special trains [21] (colloquially referred to as "Sandite trains" after the original proprietary mixture applied) and in some cases locally by hand applicators. [22]

Lineside-fitted Traction gel applicators [23] which apply liquid to the railhead as a train passes are fitted at sites where significant low adhesion regularly occurs, such as on the approach to stations.

Both of these processes are effective for a limited duration; the jetting method is ineffective as soon as the next leaf falls; the sand deposition method is more durable, although rainfall usually removes the deposited sand quickly. Another method is using a high voltage electrical spark or plasma to volatilize the deposited material, but this method has only been used experimentally, as it is hindered by high power consumption, noise and rail degradation. [2]

Lasers

Since 2018, LIRR has used laser technology provided by Laser Precision Solutions, to tackle the autumn slip slide issue, using two 25 mph (40 km/h) LaserTrains. [24]

Sanders

Locomotives and multiple units are fitted with sanders which apply a fine layer of dry sand on the railhead. This assists adhesion during braking and acceleration.

Novel methods

There are a range of novel methods being trialed for cleaning contamination from the railhead. One method uses solid CO2 ("dry ice") [25] which is fired at the track through a nozzle, removing commination through surface cooling, kinetic energy and sublimation. [26] Other methods have been trialed include microwave plasma [27] and ultrasound. [28]

Wheel slide protection

Wheel slide protection (WSP) equipment is fitted to passenger trains to manage the behaviour of wheel sets in low adhesion conditions. When the train is braking, it behaves like the ABS system in cars by releasing the brake on any axle if it detects that it is locking up. WSP can also control the traction system to prevent wheel spin when applying power.

Driving technique

Where trains have difficulty stopping during low adhesion conditions, the greatest risk is of passing a signal at danger or 'over-running' a station. At these times, train drivers adopt 'defensive driving', [4] which involves braking earlier and more gently than usual. Also, less power is applied when starting trains.

Before each leaf-fall season, train companies may arrange low-adhesion training [4] for newly qualified drivers. This consists of taking over a section of line during a quiet period. Using lineside markers each driver gets their train up to speed and then makes a full service brake application under normal adhesion conditions. The railhead is then treated with a contaminant that has a low coefficient of friction. On the second run, the driver will experience the sound and sensation of the train sliding, and the stopping distance will be considerably greater.

Although this provides only an approximation of how a train will behave during low adhesion, it does ensure that the driver can recognize the onset of wheel slide and will know the correct actions to take when it occurs.

In the UK, some passenger train operating companies publish a special 'leaf fall' timetable [29] to allow for the additional time that lighter braking and acceleration take.

Communication

Any information about the location and severity of low adhesion conditions will give train drivers warning of problems. In the UK there are several sources;

Vegetation management

Removal of deciduous trees at the lineside is a management method to control the problem; however, there is political resistance to this in populous areas.

North America

LIRR adhesion train (adhesion car is the silver/grey modified M3 car, with a red tank car to supply it) passes on the Babylon Branch in autumn to deal with leaf issues. LIRR Adhesion train passing on Babylon Line.jpg
LIRR adhesion train (adhesion car is the silver/grey modified M3 car, with a red tank car to supply it) passes on the Babylon Branch in autumn to deal with leaf issues.

Slippery rail has created severe disruptions of rail service, particularly in major metropolitan areas such as New York or Boston. In November 2006, it was blamed for roughly one-third of all Metro-North Railroad's Hudson and Harlem lines' passenger cars being taken out of service. [6] During the same period on the Long Island Rail Road, nearly 25% of cars were out of service due to slippery rail. [32] [33]

In the US, Amtrak, the Massachusetts Bay Transportation Authority, southeastern Pennsylvania's SEPTA, [34] Chicago's commuter rail service Metra, and MARC, which serves Baltimore and Washington, D.C., have all reported delays due to slippery rail. [5]

Methods for dealing with slippery rail have included trimming trees, the release of sand on the train wheels for traction, high-pressure water blasting and, most expensively, the use of high-powered laser blasts to clear the rails of leaves. [5] [35]

Metro-North has designed a system dubbed "Waterworld", which is a large flat rail car that blasts the rails with high-pressure water jets as the car moves over it. [36]

New Jersey Transit has used a similar method, which has proven effective. The device it uses is called "Aqua-Track" which, while attached to a moving rail car, sprays water at a pressure of 20,000 psi (140 MPa) on to the part of the rail where the leaves cling. [37] Since this system was introduced in 2002, the delays due to wheelslip have been reduced by over 60%. [6]

SEPTA Regional Rail's method of preventing slippery rail is the Gel Trains. These three trains spray a high-pressure mixture of Sandite on the rails; in the fall, the Gel Trains also clean the rails using the high-pressure water jet method ahead of the gel application. These trains consist of a pressure washer and gel dispenser mounted on a converted flatcar, and a tank car which carries water. They are pulled on one end by one of SEPTA's work diesels (or a diesel borrowed from a local shortline such as the West Chester Railroad), and controlled at the other end by a former LIRR "Power Pack" cab unit (one a former ALCO FA, the other a former EMD F7). However, as of 2015; The FA and F7 were retired and replaced by Comet 1 cab cars. [38] [39]

United Kingdom

In the United Kingdom, a number of rail companies change their timings and publish special "leaf fall timetables". [29]

During autumn, a fleet of Railhead Treatment Trains (RHTT) [40] run across the network using high pressure water-jetting to clean the railhead. These trains are timetabled to run between scheduled daytime services as well as during the night when less rail activity can allow the railhead contamination to build up.

The cryptic nature of rail company explanations for slippery rail and related phenomena made the phrase "leaves on the line" a standing joke, [41] and, along with variants such as "the wrong type of snow", is seen by members of the public who are not familiar with the problem as an excuse for poor service. [42] [43]

Particularly problematic local trees include the sycamore, lime, sweet and horse chestnut, ash, and poplar, which regrow or coppice after cutting back, and have large, flat leaves, which stick to the line and cause severe slippery rail. [41] Other types of tree that cause problems are quick-growing, pioneering trees, or those producing a substantial amount of leaves. Poplars are particularly troubling because they tend to shed limbs. [44]

A term current in 2003 for cutting down or cutting back trees near the lines was "lineside vegetation management". [44]

Netherlands

Slippery rail is also a problem in the Netherlands, addressed by Nederlandse Spoorwegen (NS) and ProRail. [45] To prevent wheel lock, on some routes trains are required to brake earlier and accelerate more slowly. Furthermore, some (passenger) trains are fitted with equipment to apply Sandite gel on the tracks. [46] In autumn 2016, nearly 90,000 litres (24,000 US gal) of this gel was applied on the Dutch railway network. [47] In the fall of 2014 a pilot, in collaboration with Delft University of Technology, to use lasers to remove contaminations was announced by NS and ProRail. [48]

See also

Related Research Articles

Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.

<span class="mw-page-title-main">Derailment</span> Form of train incident

In rail transport, a derailment occurs when a rail vehicle such as a train comes off its rails. Although many derailments are minor, all result in temporary disruption of the proper operation of the railway system and they are a potentially serious hazard.

<span class="mw-page-title-main">Signal passed at danger</span> Train passing stop signal without authority

A signal passed at danger (SPAD), known in the United States as a stop signal overrun (SSO) and in Canada as passing a stop signal, is an event on a railway where a train passes a stop signal without authority. This is also known as running a red.

Stiction is the force that needs to be overcome to enable relative motion of stationary objects in contact. Any solid objects pressing against each other will require some threshold of force parallel to the surface of contact in order to overcome static adhesion. Stiction is a threshold, not a continuous force. However, stiction might also be an illusion made by the rotation of kinetic friction.

<span class="mw-page-title-main">Automatic Warning System</span>

Automatic Warning System (AWS) is a railway safety system used in the United Kingdom. It provides a train driver with an audible indication of whether the next signal they are approaching is clear or at caution. Depending on the upcoming signal state, the AWS will either produce a 'horn' sound, or a 'bell' sound. If the train driver fails to acknowledge a warning indication, an emergency brake application is initiated by the AWS. However if the driver correctly acknowledges the warning indication by pressing an acknowledgement button, then a visual 'sunflower' is displayed to the driver, as a reminder of the warning.

<span class="mw-page-title-main">Track circuit</span> Electrical device used to detect the presence of trains on rail tracks

A track circuit is an electrical device used to prove the absence of a train on rail tracks to signallers and control relevant signals. An alternative to track circuits are axle counters.

<span class="mw-page-title-main">Adhesion railway</span> Railway which relies on adhesion traction to move a train

An adhesion railway relies on adhesion traction to move the train, and is the most widespread and common type of railway in the world. Adhesion traction is the friction between the drive wheels and the steel rail. Since the vast majority of railways are adhesion railways, the term adhesion railway is used only when it is necessary to distinguish adhesion railways from railways moved by other means, such as by a stationary engine pulling on a cable attached to the cars or by railways that are moved by a pinion meshing with a rack.

<span class="mw-page-title-main">Axle counter</span>

An axle counter is a system used in railway signalling to detect the clear or occupied status of a section of track between two points. The system generally consists of a wheel sensor and an evaluation unit for counting the axles of the train both into and out of the section. They are often used to replace a track circuit.

<span class="mw-page-title-main">Sandbox (locomotive)</span> Container used in locomotives to drop sand on the rail to improve traction

A sandbox is a container on most locomotives, multiple units and trams that holds sand, which is dropped on the rail in front of the driving wheels in wet and slippery conditions and on steep grades to improve traction.

<span class="mw-page-title-main">London Underground sleet locomotives</span> London Underground de-icing locomotives

Sleet locomotives were redundant London Underground cars converted to help with the removal of ice that built up on the conductor rails. The main batch of eighteen tube-gauge locomotives were built between 1938 and 1941 from motor cars originally built in 1903. They were refurbished in the 1960s using equipment removed from redundant T-stock vehicles, and were joined by a pair of surface-gauge locomotives in 1961.

Sandite is a substance used on railways in the UK, Ireland, US, the Netherlands and Belgium to combat leaves on the line, which can cause train wheels to slip and become damaged with flat spots. Sandite consists of a mixture of sand, antifreeze and steel shot.

Wheel slide protection and wheel slip protection are railway terms used to describe automatic systems used to detect and prevent wheel-slide during braking or wheel-slip during acceleration. This is analogous to ABS and traction control systems used on motor vehicles. It is particularly important in slippery rail conditions.

Locomotive wheelslip is an event that affects railway motive power usually when starting from stationary, but can also affect an engine in motion.

<span class="mw-page-title-main">Flat spot</span>

A flat spot, or wheel flat, also called spalling or shelling, is a fault in railroad wheel shape. A flat spot occurs when a rail vehicle's wheelset stops rotating while the train is still in motion, causing part of the wheel to ablate against the hard steel of the rails. Flat spots are usually caused by use of the emergency brake, or slippery (low-adhesion) conditions that cause wheels to lock up while the train is still moving. Flat spots are more common in the autumn and winter when the rails are slippery.

<span class="mw-page-title-main">Rail adhesion car</span> Vehicle used on a rail adhesion system

A rail adhesion car or rail adhesion train is a modified vehicle used on a rail adhesion system where the standard equipment does not have locomotives' rail sanding ability. In particular, it may involve tanks and dispensing equipment installed in an electric subway or rail car that is run over the rails alone or in a train to dispense sand when needed. Because of space limits under the cars, the sand or gel/sand mix tanks are installed inside the passenger space.

<span class="mw-page-title-main">Train wheel</span> Wheel designed for railway tracks

A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie, also called a truck. The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness. New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. The International Union of Railways has defined a standard wheel diameter of 920 mm (36 in), although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages.

<span class="mw-page-title-main">Rail squeal</span> Screeching rail track

Rail squeal is a screeching train-track friction sound, commonly occurring on sharp curves.

Route knowledge is one of the core skills together with train handling and a full understanding of railway rules, which the operating crew must possess in order to be able to operate a train safely.

<span class="mw-page-title-main">Decelostat</span> Railroad wheel slide protection braking system

Decelostat is a wheel slide protection system developed by Westinghouse Air Brake Company that is used in railroad cars to prevent over-braking that causes wheel-slide, a condition of reduction in friction between train wheels and rails. This low wheel/rail adhesion condition reduces braking performance and causes damage to wheels and the rails.

<span class="mw-page-title-main">2021 Salisbury rail crash</span> Railway crash in the United Kingdom

The Salisbury Rail Crash was a railway accident on 31 October 2021, at Salisbury, Wiltshire, United Kingdom. Two trains, travelling on converging lines, collided at Salisbury Tunnel Junction, approximately one mile northeast of Salisbury railway station. Fourteen people, including one of the train drivers, were taken to hospital.

References

  1. ↑ "Low Adhesion Mockery Sticks Despite the Facts". Rail.co.uk. Retrieved March 31, 2016.
  2. 1 2 Lewis, S.R.; Lewis, R.; Richards, P.; Buckley-Johnstone, L.E. (2014). "Investigation of the isolation and frictional properties of hydrophobic products on the rail head, when used to combat low adhesion". Wear. 314 (1–2): 213–219. doi:10.1016/j.wear.2013.11.024. ISSN   0043-1648.
  3. ↑ Desmond F. Moore (October 22, 2013). Principles and Applications of Tribology: Pergamon International Library of Science, Technology, Engineering and Social Studies: International Series in Materials Science and Technology. Elsevier Science. p. 311. ISBN   978-1-4831-5728-3.
  4. 1 2 3 4 5 2012 Autumn & Winter Season (Drivers' Briefing). London, UK: First Capital Connect. September 2012.
  5. 1 2 3 Holmes, Elizabeth (November 21, 2006). "Why your train is late when autumn leaves fall (free preview)". The Wall Street Journal online. Retrieved November 22, 2006.
  6. 1 2 3 Halbfinger, Caren (November 21, 2006). "'Flat wheels' deflate train commuters". The Journal News. White Plains, New York. Archived from the original on September 30, 2007. Retrieved November 22, 2006.
  7. 1 2 Summer Weather (Drivers' Briefing). London, UK: First Capital Connect. May 2012.
  8. ↑ White, Ben; Lewis, Roger (August 1, 2019). "Simulation and understanding the wet-rail phenomenon using twin disc testing" (PDF). Tribology International. 136: 475–486. doi:10.1016/j.triboint.2019.03.067. ISSN   0301-679X. S2CID   140827487.
  9. ↑ White, Ben; Kempka, Reuben; Laity, Peter; Holland, Chris; Six, Klaus; Trummer, Gerald; Buckley-Johnstone, Luke; Lewis, Roger (December 20, 2021). "Iron Oxide and Water Paste Rheology and Its Effect on Low Adhesion in the Wheel/Rail Interface" (PDF). Tribology Letters. 70 (1): 8. doi:10.1007/s11249-021-01549-0. ISSN   1573-2711. S2CID   245330956.
  10. ↑ White, BT; Nilsson, R; Olofsson, U; Arnall, AD; Evans, MD; Armitage, T; Fisk, J; Fletcher, DI; Lewis, R (May 2, 2017). "Effect of the presence of moisture at the wheel–rail interface during dew and damp conditions" (PDF). Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. 232 (4): 979–989. doi:10.1177/0954409717706251. ISSN   0954-4097. S2CID   55583850.
  11. ↑ Ishizaka, Kei; Lewis, Stephen R.; Lewis, Roger (May 15, 2017). "The low adhesion problem due to leaf contamination in the wheel/rail contact: Bonding and low adhesion mechanisms" (PDF). Wear. 378–379: 183–197. doi:10.1016/j.wear.2017.02.044. ISSN   0043-1648.
  12. ↑ Wolmar, Christian (February 20, 1995). "Disc brakes linked to rise in train "slides"". The Independent. London. Retrieved July 21, 2012.
  13. ↑ Laffan, R. M. (May 22, 1851). "The fatal collision on the Sutton Tunnel" (PDF). Railways Archive. House of Commons. pp. 7, 9.
  14. ↑ "Royal Forestry Society: Leaves on the Line". Archived from the original on July 13, 2013. Retrieved July 21, 2012.
  15. ↑ Butler, Pip (April 29, 2002). "The millipedes which stop trains". The Age. Retrieved May 26, 2015.
  16. 1 2 "Millipedes suspected in Perth train crash". The Australian. September 3, 2013. Retrieved May 26, 2015.
  17. ↑ "Caterpillars: Damage on Darling Downs". Townsville Daily Bulletin . Qld. October 24, 1938. p. 6. Retrieved October 8, 2012.
  18. ↑ "Railway Group Standards - Railway Wheelsets" (PDF). RSSB. February 2010. Retrieved December 8, 2016.
  19. ↑ "Improving track circuit actuation performance at the wheel/rail interface". RSSB. 2011. Retrieved December 6, 2016.
  20. ↑ "Adhesion". www.rssb.co.uk. Retrieved April 26, 2022.
  21. ↑ "Leaves on the line". Rail.co.uk. Retrieved December 8, 2016.
  22. ↑ "Permaquip Sand & Gel Applicators". Permaquip. Retrieved December 8, 2016.
  23. ↑ "Traction Gel Applicators". JSD Rail. Retrieved November 21, 2016.
  24. ↑ "StackPath". www.masstransitmag.com. Retrieved November 3, 2021.
  25. ↑ "Track cleaning tech could prevent rail delays". The Engineer. October 5, 2021. Retrieved March 25, 2022.
  26. ↑ Krier, Peter; White, Ben T; Ferriday, Paul; Watson, Mike; Buckley-Johnstone, Luke; Lewis, Roger; Lanigan, Joseph L (November 1, 2021). "Vehicle-based cryogenic rail cleaning: an alternative solution to 'leaves on the line'". Proceedings of the Institution of Civil Engineers - Civil Engineering. 174 (4): 176–182. doi:10.1680/jcien.21.00105. ISSN   0965-089X. S2CID   237701740.
  27. ↑ Swan, Julian; Radoiu, Marilena (October 14, 2020). "Microwave Plasma System for Continuous Treatment of Railway Track". Technologies. 8 (4): 54. doi: 10.3390/technologies8040054 . ISSN   2227-7080.
  28. ↑ "The Adhesion Rail Riddle - Ensuring Trains Can Brake | Engineering | University of Southampton". www.southampton.ac.uk. Retrieved March 25, 2022.
  29. 1 2 "National Rail Enquiries - Leaf Fall Timetable Changes - Autumn 2021". www.nationalrail.co.uk. Retrieved April 26, 2022.
  30. ↑ "Online Rulebook – Module TW1 – Section 28.1 Rail-head adhesion" (PDF). RSSB. Archived from the original (PDF) on September 29, 2011. Retrieved December 10, 2016.
  31. ↑ "Online Rulebook – Module TW1 – Section 28.2 Arranging a controlled test stop" (PDF). RSSB. Archived from the original (PDF) on September 29, 2011. Retrieved December 10, 2016.
  32. ↑ Aitchison, Gavin (November 21, 2006). "Leaves on line cause rail delays". The Press. York. Retrieved November 22, 2006.
  33. ↑ "Commuters, expect train delays". WABC-TV. New York. November 22, 2006. Retrieved November 22, 2006.
  34. ↑ "SEPTA". Archived from the original on November 9, 2006. Retrieved November 23, 2006.
  35. ↑ "Lasers clear leaves on the line". Physicsweb. May 2, 2002. Retrieved January 22, 2007.
  36. ↑ Silberstein, Judy (November 15, 2006). "Commuters Warned Of "Slippery Rail" Delay". Larchmont Gazette. New York State. Retrieved November 22, 2006.
  37. ↑ "New Jersey Transit". www.njtransit.com. Retrieved November 16, 2019.
  38. ↑ Almeida, John P. "SEPTA Gel Train with F7 622 Philadelphia PA November 12, 2006". Railfan Pictures of the Day. The Philadelphia Chapter of the National Railway Historical Society. Retrieved February 12, 2013.
  39. ↑ Almeida, John P. "What do you use to rescue a SEPTA gel train? Another SEPTA gel train! October 16, 2008". Railfan Pictures of the Day. The Philadelphia Chapter of the National Railway Historical Society. Retrieved February 12, 2013.
  40. ↑ "Railhead Treatment Trains". Rail . 1 October 2014. Retrieved 1 April 2016.
  41. 1 2 "Leaves on the Line". The Royal Forestry Society . Archived from the original on 17 January 2008.
  42. ↑ Martin Wainwrightc (20 April 2004). "Wrong type of pressure halts new trains". The Guardian .
  43. ↑ Jon Yuill (25 July 2003). "Going Loco – your bizarre train tales". BBC News .
  44. 1 2 John May (22 October 2003). "Get a Grip". The Guardian.
  45. ↑ Article, International Railway Journal, October 2003
  46. ↑ Archived at Ghostarchive and the Wayback Machine : "Sandite: slim recept tegen blad op het spoor". YouTube .
  47. ↑ "Weg met die smurrie op spoor". ProRail. September 29, 2017.
  48. ↑ "NS zet laser in". NRC Handelsblad . August 14, 2014.
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