Taunton 66148 66116 railhead treatment train

Slippery rail, or low railhead adhesion, 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 A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

that adhere to the railhead (top surface) of

railway tracks Railway track ( and UIC terminology) or railroad track (), also known as permanent way () or "P way" ( and Indian English), is the structure on a railway or railroad consisting of the rails, fasteners, sleepers (railroad ties in American E ...

. The condition results in significant reduction in

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

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".

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. In heavily deciduous forested areas like the American Mid-Atlantic states,

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

, 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 {{Short pages monitor

Effects

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

locomotive A locomotive is a rail transport, rail vehicle that provides the motive power for a train. Traditionally, locomotives pulled trains from the front. However, Push–pull train, push–pull operation has become common, and in the pursuit for ...

s and

multiple units A multiple-unit train (or multiple unit (MU)) is a self-propelled train composed of one or more Coach (rail), carriages joined, and where one or more of the carriages have the means of propulsion built in. By contrast, a locomotive-hauled ...

are equipped with

Wheel slide protection 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 u ...

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'), 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. Where the problem is severe, Track Circuit Actuators 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.

Mitigation measures

Railhead treatment

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 (colloquially referred to as "

Sandite Sandite is a Chemical substance, substance used on railways in the UK, Republic of Ireland, Ireland, US, the Netherlands and Belgium to combat Slippery rail, leaves on the line, which can cause train wheels to slip and become damaged with flat ...

trains" after the original proprietary mixture applied) and in some cases locally by hand applicators. Lineside-fitted Traction gel applicators 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.

Lasers

Since 2018, LIRR has used laser technology provided by Laser Precision Solutions, to tackle the autumn slip slide issue, using two LaserTrains.

Sanders

Locomotives and

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") which is fired at the track through a nozzle, removing commination through surface cooling, kinetic energy and sublimation. Other methods have been trialed include microwave plasma and ultrasound.

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', 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 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 Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

. 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 In the railway system of Great Britain, a train operating company (TOC) is a railway undertaking operating passenger trains under the collective National Rail brand. TOCs have existed since the privatisation of the network under the Railways ...

publish a special 'leaf fall' timetable 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; * Regular blackspots, known as ''Areas of known low adhesion'' are published in the

Sectional Appendix In Great Britain, the Sectional Appendix is a Great Britain railway technical manuals, railway document compiled by Network Rail and is the official definition of railway infrastructure, giving a detailed description of all railway lines owned b ...

and form part of the drivers' Route Knowledge which they are examined on. * Lineside signs showing the start and end of known regular low adhesion areas are provided at some locations. * Drivers are required by the Rulebook, to report to the signaller immediately either, any low railhead adhesion at a location not published in the Sectional Appendix, or any exceptionally poor rail adhesion at locations which are published in the Sectional Appendix. * After receiving a report of low adhesion conditions, the signaller will contact drivers of following trains by radio to warn them. If it is safe to do so, the signaller may tell a driver to carry out a controlled test stop. That driver will then stop the train using the brake force appropriate to normal conditions for the weather and conditions at that time of year, and report back to the signaller.

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. Slippery rail has created severe disruptions of rail service, particularly in major metropolitan areas such as

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

Boston Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...

. In November 2006, it was blamed for roughly one-third of all

Metro-North Railroad The Metro-North Commuter Railroad Company , also branded as MTA Metro-North Railroad and commonly called simply Metro-North, is a suburban commuter rail service operated by the Metropolitan Transportation Authority (MTA), a New York State publ ...

Hudson Hudson may refer to: People * Hudson (given name) * Hudson (surname) * Hudson (footballer, born 1986), Hudson Fernando Tobias de Carvalho, Brazilian football right-back * Hudson (footballer, born 1988), Hudson Rodrigues dos Santos, Brazilian f ...

and

Harlem Harlem is a neighborhood in Upper Manhattan, New York City. It is bounded roughly by the Hudson River on the west; the Harlem River and 155th Street on the north; Fifth Avenue on the east; and Central Park North on the south. The greater ...

lines' passenger cars being taken out of service. During the same period on the

Long Island Rail Road The Long Island Rail Road , or LIRR, is a Rail transport, railroad in the southeastern part of the U.S. state of New York (state), New York, stretching from Manhattan to the eastern tip of Suffolk County, New York, Suffolk County on Long Islan ...

, nearly 25% of cars were out of service due to slippery rail. In the US,

Amtrak The National Railroad Passenger Corporation, Trade name, doing business as Amtrak (; ), is the national Passenger train, passenger railroad company of the United States. It operates intercity rail service in 46 of the 48 contiguous United Stat ...

, the

Massachusetts Bay Transportation Authority The Massachusetts Bay Transportation Authority (abbreviated MBTA and known colloquially as "the T") is the public agency responsible for operating most public transportation services in Greater Boston, Massachusetts. The MBTA transit network in ...

, southeastern

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

SEPTA SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...

's commuter rail service

Metra Metra is the primary commuter rail system in the Chicago metropolitan area serving the city of Chicago and its surrounding suburbs via the Union Pacific Railroad, BNSF Railway, and other railroads. The system operates 243 train station, stati ...

, and MARC, which serves

Baltimore Baltimore is the most populous city in the U.S. state of Maryland. With a population of 585,708 at the 2020 census and estimated at 568,271 in 2024, it is the 30th-most populous U.S. city. The Baltimore metropolitan area is the 20th-large ...

and Washington, D.C., have all reported delays due to slippery rail. Methods for dealing with slippery rail have included trimming trees, the release of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

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. 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.

New Jersey Transit New Jersey Transit Corporation, branded as NJ Transit or NJTransit and often shortened to NJT, is a state-owned public transportation system that serves the U.S. state of New Jersey and portions of the states of New York and Pennsylvania. It ...

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 on to the part of the rail where the leaves cling. Since this system was introduced in 2002, the delays due to wheelslip have been reduced by over 60%.

Regional Rail Regional rail is a public transport, public rail transport service that operates between towns and cities. These trains operate with more stops than inter-city rail, and unlike commuter rail, operate beyond the limits of urban areas, connectin ...

'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 The West Chester Railroad is a privately owned and operated Heritage railway, tourist railroad that runs between Market Street in West Chester, Pennsylvania, in Chester County, Pennsylvania, Chester County, and the village of Glen Mills, Pennsy ...

), 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 The EMD F7 is a model of diesel-electric locomotive produced between February 1949 and December 1953 by the Electro-Motive Division of General Motors (EMD) and General Motors Diesel (GMD). Although originally promoted by EMD as a freight-h ...

). However, as of 2015; The FA and F7 were retired and replaced by Comet 1 cab cars.

United Kingdom

In the United Kingdom, a number of rail companies change their timings and publish special "leaf fall timetables". During autumn, a fleet of Railhead Treatment Trains (RHTT) 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, 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. Particularly problematic local trees include the

sycamore Sycamore is a name which has been applied to several types of trees, but with somewhat similar leaf forms. The name derives from the Ancient Greek () meaning . Species of otherwise unrelated trees known as sycamore: * ''Acer pseudoplatanus'', a ...

, lime,

sweet Sweetness is a basic taste most commonly perceived when eating foods rich in sugars. Sweet tastes are generally regarded as pleasurable. In addition to sugars like sucrose, many other chemical compounds are sweet, including aldehydes, ketones, ...

and horse chestnut, ash, and poplar, which regrow or

coppice Coppicing is the traditional method in woodland management of cutting down a tree to a tree stump, stump, which in many species encourages new Shoot (botany), shoots to grow from the stump or roots, thus ultimately regrowing the tree. A forest ...

after cutting back, and have large, flat leaves, which stick to the line and cause severe slippery rail. 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. A term current in 2003 for cutting down or cutting back trees near the lines was "lineside vegetation management".

Netherlands

Slippery rail is also a problem in the Netherlands, addressed by

Nederlandse Spoorwegen (, , NS ) is the principal passenger railway operator in the Netherlands. It is a Dutch state-owned company founded in 1938. The rail infrastructure is maintained by network manager ProRail, which was split off from NS in 2003. Freight operato ...

(NS) and ProRail. 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

gel on the tracks. In autumn 2016, nearly of this gel was applied on the Dutch railway network. In the fall of 2014 a pilot, in collaboration with

Delft University of Technology The Delft University of Technology (TU Delft; ) is the oldest and largest Dutch public university, public Institute of technology, technical university, located in Delft, Netherlands. It specializes in engineering, technology, computing, design, a ...

, to use lasers to remove contaminations was announced by NS and ProRail.

References

{{DEFAULTSORT:Slippery Rail Rail transport operations Transport and the environment Leaves nl:Vlakke plaats