What is under a train?

[daveklepper]

From Steve Sattler:

 

A review of what is under a train.

        Watching a train pass-by   is impressive but knowing how the metal rails and the sleepers that hold the whole system together function is 'real knowledge'.

The sleeper:-   What is it?

    A railroad tie [American terminology] or railway sleeper [The rest of the world, especially Britain] is the basic and geometric support for the rails in railroad tracks. Generally laid perpendicular to the rails, ties transfer loads to the track-ballast subgrade, hold the rails upright and keep them spaced to the correct gauge.

     Railroad ties are traditionally made of wood, but pre-stressed concrete is now also widely used, especially in Europe and Asia. Steel ties are common on secondary lines in the UK. The new plastic composite ties are also been laid in some countries. They are still far less common than wood or concrete. As of January 2008, the approximate market share in North America for traditional and wood ties was 91.5%, the remainder being concrete, steel, Azobe (a wood; known as red ironwood) and plastic composite.

    In the USA approximately 3,520 wooden crossties are used per mile of mainline railroad track, and this creates a distance of  18" between ties. In the UK, 2,640 per mile (30 per 60 ft rail) on main lines is the common standard.

    Rails in the US may be fastened to the tie by a railroad spike of  iron/steel onto a  baseplate screwed to the tie and secured to the rail by a proprietary fastening system. (A clip)    In Europe such systems can be a Vossloh [Germany] or Pandrol unit [UK].

    The track on a railway or railroad, is also known as the permanent way. It is the structure consisting of the rails, fasteners, railroad ties (sleepers, in British English) and ballast (or slab track), plus the underlying subgrade. It enables trains to move by providing a dependable surface for their wheels to roll upon. For clarity it is often referred to as railway track (British English and standard international terminology) or railroad track (an Americanism). Tracks where electric trains or trams run are equipped with an electrification system such as an overhead electrical power line or an additional [third] electrified rail.

The term permanent way refers to the track and in addition to any lineside structures such as fences.

    The permanent way also has the common meaning that this ‘strip’ is for trains only, and persons, animals, or any blocking object should never be there.

 

 

Diagram:

A modern Railway track showing traditional features of ballast, part of sleeper and fixing mechanisms

This is a section through railway track and foundation showing the ballast and formation layers. The layers are slightly sloped to help drainage.
Sometimes there is a layer of rubber matting (not shown) to improve drainage, and to dampen sound and vibration.

 

    There are constant modern technical developments, but the overwhelmingly dominant track form worldwide consists of flat-bottom steel rails supported [clipped] on timber or pre-stressed concrete sleepers, which are themselves laid on crushed stone ballast.

    Most railroads with heavy traffic utilize continuously welded rails supported by sleepers attached via base plates that spread the load. A plastic or rubber pad is usually placed between the rail and the tie plate where concrete sleepers are used. The rail is usually held down to the sleeper with resilient fastenings [clips], although cut spikes are still widely used in North America.

For much of the 20th century, the rail track used softwood timber sleepers and jointed rails [metal plates bolted and thus joined two separate rails], and a considerable extent of this track type remains on secondary and tertiary routes. The rails were typically of a flat bottom section fastened to the sleepers with dog spikes through a flat tie plate in North America and Australia.

In British and Irish regions,  typically, the rails were/are of a bullhead section carried in cast iron chairs (clips).      

   Historically, The London, Midland and Scottish Railways pioneered the conversion to flat-bottomed rail.   Attempts to have some rails designed to be turned over, after wear-in order to be reused, when the top surface had become worn - turned out to be unworkable in practice because the underside was usually ruined by fretting from the chairs.

    Jointed rails were used at first because contemporary [welding] technology did not offer any alternative. However, the intrinsic weakness in resisting vertical loading results in the ballast becoming depressed and a heavy maintenance workload is imposed to prevent unacceptable geometrical defects at the joints. The joints also needed to be lubricated, and wear at the fishplate (the joint bar or plate ) mating surfaces needed to be rectified by shimming. For this reason, jointed track is not financially appropriate for heavily operated railroads.

    Timber sleepers are of many available timbers, and are often treated with creosote, copper-chrome-arsenate, or other wood preservative. Pre-stressed concrete sleepers are often used where timber is scarce and where tonnage or speeds are high. Steel is used in some applications.

The track ballast is customarily crushed stone, and the purpose of this is to support the sleepers and allow some adjustment of their position, while allowing free drainage.

It is still a wonder to many physicists that the crushed stone ballast doesn’t seep away laterally, as the many trains run over it. Logic demands that as the heavy trains that run over the rails, the vertical pressure will force the ballast to slide side-ways, and eventually slip away. Apparently, the stones lock themselves together and thus this ballast base stays solid and not fluid.

Furthermore, the weather [rain] and occasional flooding, doesn’t damage the ballast and from year to year, old ballast continues to function. Routine maintance, never-the -less will refresh the ballast with a new layer-periodically.

Ballast-less track.

       A disadvantage of traditional track structures is the heavy demand for maintenance, particularly surfacing (tamping) and lining to restore the desired track geometry. and smoothness of vehicle running. Weakness of the subgrade and drainage deficiencies also lead to heavy maintenance costs. This can be overcome by using ballast-less track. In its simplest form this consists of a continuous slab of concrete (like a highway structure) with the rails supported directly on its upper surface, and in many cases with the use of a plastic or rubber resilient pad.

There are a number of proprietary systems, and variations include a continuous reinforced concrete slab, or alternatively the use of pre-cast pre-stressed concrete units laid on a base layer. Many permutations of design have been put forward and are in use.

However, ballast-less track has a high initial cost, and in the case of existing railroads the upgrade to such requires closure of the route for a long period. Its whole-life cost can be lower because of the reduction in maintenance. Ballast-less track is usually considered for new very high speed or very high-loading routes, in short extensions that require additional strength (e.g. rail stations), or for localized replacement where there are exceptional maintenance difficulties, for example in tunnels. Some rubber-tyred metros use ballast-less tracks. [Paris]

Continuous longitudinally supported track.

    Another concept-and with historic value.

Early railways, (UK: the 1840s) experimented with continuous bearing rail-track, in which the rail was supported along its whole length. Some examples are; Brunel's Baulk Road on the Great Western Railway, as well as use on the Newcastle and North Shields Railway. Also, on the Lancashire and Yorkshire Railway to a design by John Hawkshaw, and elsewhere. Continuous-bearing designs were also promoted by other engineers.

 USA: Thesystem was trialed on the Baltimore and Ohio railway in the 1840s, but was found to be more expensive to maintain than rail with cross-sleepers.

From 1976 onwards: Later applications of continuously supported track include Balfour Beatty”s  'embedded slab track', which uses a rounded rectangular rail profile  embedded in a - pre-cast- concrete base. This 'embedded rail structure', used in the Netherlands since 1976, initially used a conventional ‘simple’ rail embedded in concrete, and later (the 1990s) evolved to use a 'mushroom' shaped rail profile.

2002: A newer version for light rail using a rail supported in an asphalt/concrete filled steel trough has also been developed. The evolution of even newer technologies is on the horizon. Rail manufactures and train operators are constantly looking at cheaper technologies, efficiency in installation, low maintance and weather proofing.  The economics of running a train service-either cargo or passenger is critical in the modern world.

The Ladder track:

This is an evolution of the Baulk Road concept.

The rails are supported by metal sleeper, under the working rails-in the same direction as the rails, but the whole rail and support sits on rung-like cross-bars.

This ladder track can be laid over a ballast, or ballast-less base.

       A variation of a laid ladder on a thin ballast bed is used in Japan, at many stations. A common example is the Shinagawa Station, in Tokyo. The metal rails sit on cross bars of iron, [3 meters between cross bars], and everything is bolted into place.

Classification, a review:

   Since railways are over 400 years old, there are several historical systems in place, which are also traditional.

        M… Types by material.

• Stone
• Wood
• Concrete
• Steel
• Plastic

         T… Types by system or geometry.

• Y shaped ties
• Twin ties
• Wide ties
• Bi-block ties
• Frame ties
• Ladder track

C…The Clips.

 

M.1… The Stone block.

Example: a stone block from the Kilmarnock and Troon Railway [UK]

    This was the type of railroad tie used on the predecessors of the first true railway (The Liverpool and Manchester Railway) consisted of a pair of stone blocks laid into the ground, with the chairs holding the rails fixed to those blocks. One advantage of this method of construction was that it allowed horses to tread the middle path without the risk of tripping. Never-the less, in railway usage with ever heavier locomotives, it was found that it was hard to maintain the correct gauge. The stone blocks were in any case unsuitable on soft ground, such as at Chat Moss, where timber ties had to be used. In modern usage, Bi-block ties with a tie rod between them are somewhat similar.

M.2... Wooden. (an old system, well-known and still in general use)

There are many variations of fastening the rails to wooden ties

    Historically wooden rail ties were made by hewing with an axe, called axe ties or sawn to achieve at least two flat sides. A variety of softwoods and hardwoods timbers are used as ties. Oak, Jarrah and Karri being popular hardwoods, although increasingly difficult to obtain, especially from sustainable sources. Some lines use softwoods, including Douglas fir; while they have the advantage of accepting treatment more readily, they are more susceptible to wear but are cheaper, lighter (and therefore easier to handle) and more readily available. Softwood is treated, and creosote [a tar-like carbon-based sealant] is the most common preservative for railway ties. Other preservatives, sometimes used are pentachlorophenol, or chromated copper arsenate.

    Sometimes non-toxic preservatives are used, such as copper azole or micronized copper. New Boron-based wood preserving technology is being employed by major US railroads in a dual treatment process in order to extend the life of wood ties in wet areas.  Some timbers (such as Sal, Mora, Jarrah or Azobé) are durable enough that they can be used untreated.

    Problems with wooden ties include rot, splitting, insect infestation, plate-cutting, [also known as chair shuffle in the UK (abrasive damage to the tie caused by lateral motion of the tie plate)] and spike-pull (where the spike is gradually loosened from the tie).

Wooden ties can, of course, catch fire; as they age they develop cracks that allow sparks to lodge so that they catch fire more easily. California has seen this problem recently and in many different sites.

Historically, [1908-through WW1 and even later, up to 1920]  The Hejaz railway [over 1300 kms long], in East Palestine, was constantly suffering from the theft of the wooden sleepers by Bedouin. This imported wood –[from Belgium, predominately ]-  was prime camp-fire material.

M.3... The Concrete sleeper.

    Concrete ties are cheaper and easier to obtain than timber^, and better able to carry higher axle-weights and sustain higher speeds. Their greater weight ensures improved retention of track geometry, especially when installed with continuous-welded rail. Concrete ties have a longer service life and require less maintenance than timber due to their greater weight, which helps them remain in the correct position longer. Concrete ties need to be installed on a well-prepared subgrade with an adequate depth on free-draining ballast to perform well. Concrete ties amplify wheel noise, so wooden ties are often used in densely populated areas.

    On the highest categories of line in the UK (those with the highest speeds and tonnages), pre-stressed concrete ties are the only ones permitted by Network rail standards.

    Most European railways also now use concrete bearers [sleepers] in switches and crossing layouts due to the longer life and lower cost of concrete bearers compared to timber, which is increasingly difficult and expensive to source in sufficient quantities and quality.

    Similarly, Environment-friendly organizations are keen to keep our planetary forests intact, rather than have logging companies destroying natural forests to supply -also- wooden sleepers.

    Concrete ties in the USA, especially the newer projects-are  now are placed 24 inches apart—when the rails are continuously welder together [no clickety-clack]- as opposed to 19 inches for the original wooden ties. Another lesson from the concrete ties is that under-extreme weather conditions [NE of the USA; snow, ice, extreme heat and hurricanes] the concrete tie is superior to the wooden tie as a base for stability and less maintance.

A special case; Amtrak discovered in the late 80-early 90s, that some of their concrete ties were sub-standard, and had to be replaced. [They crumbled under direct pressure]. Amtrak sued the manufacture, who later declared bankruptcy. Never-the-less Amtrak recovered most of the costs  involved.

M.4...  Steel ties.  [Steel sleepers]

    Steel ties are formed from pressed steel and are trough-shaped in section. The ends of the tie are shaped to form a "spade" which increases the lateral resistance of the tie. Housings to accommodate the fastening system are welded to the upper surface of the tie. Steel ties are now in widespread use on secondary or lower-speed lines in the UK where they have been found to be economical to install due their ability to be installed on the existing ballast bed. Steel ties are lighter in weight than concrete and able to stack in compact bundles unlike timber. Steel ties can be installed onto the existing ballast, unlike concrete ties which require a full depth of new ballast. Steel ties are 100% recyclable and require up to 60% less ballast than concrete ties and up to 45% less than wood ties.

    Historically, steel ties have suffered from poor design and increased traffic loads over their normally long service life. These aged and often obsolete designs limited load and speed capacity but can still be found in many locations globally and performing adequately despite decades of service. There are great numbers of steel ties with over 50 years of service and in some cases they can and have been rehabilitated and continue to perform well.

East Palestine and Arabia:

    Steel ties were also used in specialty situations, such as the Hejaz railway in the Palestine and Arabian regions, which had an ongoing problem with Bedouin who would steal wooden ties for campfires.

In Israel:

    Steel sleepers were used on the whole old ‘Tel-Aviv South-Jerusalem old line’ until its closure in 1998; they were tied to German UIC 49 rails received as compensation for the holocaust. Some of these rails were used only between Beit-Shemesh and Jerusalem, and some also, between Na'an and Beer-Sheva.  

 Modern steel ties handle heavy loads well, have a proven record of performance in signalized track, and handle adverse track conditions. [snow, ice, heavy winds, and floods]. Of high importance to railroad companies is the fact that steel ties are more economical to install in new construction than creosote-treated wood ties and concrete ties. Steel ties are utilized in nearly all sectors of the worldwide railroad systems including heavy-haul, hilly, regional, short-lines, mining, electrified passenger lines (OHLE) and all manner of industries.       

    Notably, steel ties (bearers) have proven themselves over the last few decades to be advantageous in turnouts (switches/points) and provide the solution to the ever-growing problem of long timber ties for such use.

    When insulated to prevent conduction through the ties, steel ties may be used with track circuit-based train detection, sensor communication and track integrity systems. Without insulation, steel ties may only be used on lines without block signaling and level crossings or on lines that use other forms of train detection such as axle counters.

Rust, theft and lighting strikes are no longer considered a problem with steel ties.

M.5… Plastics ties. [Sleepers from plastics, composites, or recycled materials]

    In more recent times, a number of companies are selling composite railroad ties manufactured from recycled plastic resins and recycled rubber. Manufacturers claim a service life longer than wooden ties with an expected lifetime in the range of 30–80 years. Furthermore, these ties are impervious to rot and insect attack, and that they can be modified with a special relief on the bottom to provide additional lateral stability.

 In some main track applications, the hybrid plastic tie has a recessed design to be completely surrounded by ballast.

    Aside from the environmental benefits of using recycled material, plastic ties usually replace timber ties soaked in creosote, the latter being a toxic chemical, and are themselves recyclable. Hybrid plastic railroad ties and composite ties are used in other rail applications such as underground mining operations, industrial zones, humid environments and densely populated areas. Hybrid railroad ties are also used to be partly exchanged with rotten wooden ties, which will result in continuous track stiffness. Hybrid plastic ties and composite ties also offer benefits on bridges and viaducts, because they lead to better distribution of forces and reduction of vibrations into respectively bridge girders or the ballast. This is due to better damping properties of hybrid plastic ties and composite ties, which will decrease the intensity of vibrations as well as the sound production.

    The UK: In 2009, Network Rail announced that it would begin replacing wooden ties with recycled plastic ones made by I-Plas Ltd of Halifax, West Yorkshire; but then, I-Plas became insolvent in October 2012.

     New Zealand: In 2012, New Zealand ordered a trial batch of "EcoTrax" brand recycled composite ties from Axion for use on turnouts and bridges, but then Axion filed for bankruptcy in December 2015. These ties are developed by Dr. Nosker at Rutgers University.

    Holland: In 2014 the KLP Hybrid Plastic Tie, by Lankhorst Engineered Products of Sneek, Netherlands, won the Privatbahn Innovation Award in the category of Track and Infrastructure.

Ties may also be made from fiberglass.

In Germany, some research is been conducted with soft or flexible ties. This new concept could possibly reduce wear and noise. It still needs to be tested under real and long-term conditions.

[Siemens [Germany]  and Trelleborg [Sweden] are also testing plastic/composite rails to replace the traditional metal rails.]

T.1 … Non-conventional tie forms.

T.1.1   Y-shaped ties. [A triangle as a base]

Y tie track next to conventional track

1983:  An unusual form of tie is the Y-shaped tie, first developed in 1983. Compared to conventional ties the volume of ballast required is reduced due to the load-spreading characteristics of the Y-tie. Noise levels are high but the resistance to track movement is very good. For curves the three-point contact of a Y steel tie means that an exact geometric fit cannot be observed with a fixed attachment point. This creates a problem as the ties are laid.

The cross section of the ties is an I-beam.

2006: The use of Y-shaped ties is still limited and  less than 1,000 km of Y-tie track had been built. Some 90% of these ties are in Germany.

T.1.2   Twin ties

The ZSX Twin tie is manufactured by Leonhard Moll Betonwerke GmbH & Co KG and is a pair of two pre-stressed concrete ties longitudinally connected by four steel rods. The design is said to be suitable for track with sharp curves, track subject to temperature stress such as that operated by trains with eddy brakes, and bridges, and as transition track between traditional track and slab track or bridges.

T.1.3   Wide ties

Concrete mono-block ties have also been produced in a wider form (e.g. 57 cm) such that there is no ballast between the ties. This wide tie increases lateral resistance and reduces ballast pressure. The system has been used in Germany where wide ties have also been used in conjunction with the GETRAC A3 ballast-less track systems.

T.1.4   Bi-block ties [France]

Bi-block (or twin-block) ties consist of two concrete rail supports joined by a steel bar. Advantages include increased lateral resistance and lower weight than monobloc concrete ties, as well as elimination of damage from torsional forces on the ties center due the more flexible steel connections. This tie type is in common use in France, and are used on the high-speed TGV lines.  Bi-block ties are also used in ballast-less track systems.

T.1.5   Frame ties. [Austria and Germany]

Frame ties (German: Rahmenschwelle) comprise both lateral and longitudinal members in a single monolithic concrete casting. This system is popular in Austria. In the Austrian system the track is fastened at the four corners of the frame and is also supported midway along the frame. Adjacent frame ties are butted close to each other. Advantages of this system over conventional cross increased support of track. In addition, construction methods used for this type of track are similar to those used for conventional track.

T.1.6   Ladder track.

In the ladder track concept, the ties are laid parallel to the rails and are several meters long. The structure is similar to Isambard Kingdom Brunel’s baulk track [1836]. These longitudinal ties can be used with ballast, or with elastomer supports on a solid non-ballasted support.

 

C.0…   Fastening rails to railroad ties.

    A rail fastening system is a means of fixing rails to railroad ties (an Americanism) or sleepers (a British-ism). The terms rail anchors, tie plates, chairs and track fasteners are used to refer to parts or all of a rail fastening system. Various types of fastening have been used over the years.

Elements of a baseplate-based rail fastening system

1.   Screw for fixing plate to sleeper

2.   Elastomeric pad supporting rail

3.   Tension washer

4.   Rail clamp

5.   Tensioning bolt (nut not shown)

6.   Baseplate

 

 

C.1…   History

    The earliest wooden rails were fixed to wooden sleepers by pegs through holes in the rail, or by nails.

By the 18th century, cast iron rails had come into use, and also had holes in the rail itself to allow them to be fixed to a support. 18th century developments such as the flanged and fish belied rail also had holes in the rail itself; when stone block sleepers were used the nails weredriven into a wooden blockwhich had been inserted into a recess in the block. The first chair [external clip] for a rail is thought to have been introduced in 1797 which attached to the rail on the vertical web via bolts.

 

By the 1820s the first shaped rolled rails had begun to be produced initially of a T shape which required a chair to hold them; the rails were held in position by iron wedges (which sometimes caused the rail to break when forced in) and later by wooden wedges, which eventually became the standard. 

    In the 1830s Robert L. Stevens invented the flanged 'tee' rail (actually a distorted I beam), which had a flat bottom and required no chair; a similar design was the contemporary bridge rail (of inverted U section with a bottom flange and laid on longitudinal sleepers); these rails were initially nailed directly to the sleeper.

    In North American practice the flanged T rail became the standard, later being used with tie-plates. Elsewhere T rails were replaced by bull-head rails of a rounded 'I' or 'figure-8' appearance which still required a supporting chair. Eventually the flanged T rail became commonplace on all the world's railways, though differences in the fixing system still exist.

C.2…    Symbolism and Significance

    A Golden Tie, also known as a Golden Spike or The Last Spike, may be used to symbolize the start or the completion of an endeavor. These are usually of silver or another precious material.

Historically, a ceremonial Golden Spike driven by Leland Stanford connected the rails of the First Transcontinental Railroad across the United States. The valuable rail fastening spike represented the merge of the Central Pacific and Union Pacific railroads on May 10, 1869, at Promontory Summit, Utah Territory. The rail spike has entered American popular consciousness in this manner; the driving of the Golden Spike was a key point in the development of the western seaboard in North America and was recognized as a national achievement and demonstration of progress. Since then , railroad workers have been celebrated in popular culture, including in song and verse.

   Most recently, a Golden Spike marked the completion of the longest transportation tunnel in the world, the Gotthard Base Tunnel, which opened 1 June 2016. Full rail service began on 11 December 2016. Its functional length is 57.09 km (35.5 mi) and it is the world's deepest traffic tunnel.

     C.3…    Spikes and screws

C.3.1   Rail spikes

 

Dog spike

From 1832:   A rail spike (also known as a cut spike or crampon) is a large nail with an offset head that is used to secure rails and base plates to railroad ties (sleepers) in the track. Robert Livingston Stevens is credited with the invention of the rail spike, the first recorded use of which was in 1832. The railroad spike was an invention which resulted from the state of industrialization in the United States in the early 19th century: English mainline railways of that period used heavy and expensive cast iron chairs to secure T-shaped rails; instead, Stevens added a supporting base to the T rail which could be fixed with a simple spike. In 1982, the spike was still the most common rail fastening in North America. Common sizes are from ⁹⁄₁₆ to ¹⁰⁄₁₆-inch square and 5 ¹⁄₂ to 6 inches long.

This picture is of some rusted Railroad spikes of the old Jezreel Valley Railway (part of the 1908 Hejaz railway), found near Kfar Baruch.  [Also known as the Rakevet HaEmek]

    A rail spike is roughly chisel-shaped and with a flat edged point; the spike is driven with the edge perpendicular to the grain, which gives greater resistance to loosening. The main function is to keep the rail in gauge. When attaching tie plates, the attachment is made as strong as possible, whereas when attaching a rail to tie or tie plate the spike is not normally required to provide a strong vertical force, allowing the rail some freedom of movement.

On smaller scale jobs spikes are still driven into wooden sleepers by hammering them with a spike maul [a hammer]. Though this manual work has been largely replaced by hydraulic tools, and machines, commonly called "spikers"

(A machine that removes spikes is called a "spike puller"). 

Splitting of the wood can be limited by pre-boring spike holes or adding steel bands around the wood.

Standards:  For use in the United States three basic standards are described in the ASTM A65 standard, for different carbon steel contents. In the USA, legal issues have forced railroad companies to have high quality and ‘standard issue’ spikes in use on all new work, and any repair or replacement work on older sections of rail.

C.3.2   A dog spike is functionally equivalent to a cut spike and is also square in horizontal section and of similar dimensions, but has a pointed penetrating end, and the rail (or "plate holding") head has two lugs on either side, giving the impression of a dog's head and aiding spike removal.

C.3.3   Chair screws.

          Chair screw   (French: Tire-fonds)

 

Rusted chair screw

 

A chair screw is a large (~6 in or 152 mm length, slightly under 1 in or 25 mm diameter) metal screw used to fix a chair (for bullhead rail), baseplate (for flat bottom rail) or to directly fasten a rail. Chair screws are screwed into a hole bored in the sleeper. The chair screw has a higher cost to manufacture than the rail spike, but has the advantage of greater fixing power - approximately twice that of a rail spike - -and can be used in combination with spring washers.

1860:   The chair screw [French= tire-fond] was first introduced in 1860 in France) and then became common in continental Europe.

A dog screw is a tradename variant of the screw spike.

C.3.4    Fang bolts.

Fang bolts or rail anchor bolts have also been used for fixing rails or chairs to sleepers. The fang bolt is a bolt inserted through a hole in the sleeper with a fanged nut that bites into the lower surface of the sleeper. For fastening flat-bottomed rails, an upper-lipped washer can be used to grip the edge of the rail. They are more resistant to loosening by vibrations and movement of the rail. They are more effective than spikes and screws and so are used in positions such as switch -points, tie plates and on sharp curves.

C.3.5    Spring spikes [A form of staple].

Spring spike fastener (German: Oberbau Hf )

Spring spikes or elastic rail spikes are used with flat-bottomed rail, baseplates and wooden sleepers. The spring spike holds the rail down and prevents tipping and also secures the baseplate to the sleeper. The Macbeth spike (trade name) is a two-pronged U-shaped staple-like spike bent so that it appears M-shaped when viewed from the side. Inverted J-shaped single pointed spikes have also been used.

C.4    Fixing equipment.

The spike maul, also known as a spiking hammer, is a type of sledgehammer with a long thin head which was originally used to drive spikes. This was hard work and needed a degree of skill.

    Manual hole drilling and spike or screw insertion and removal have been replaced by semi-automated or automated machines, which are driven electrically, by pneumatics, by hydraulics, or are powered by a two-stroke engine. Machines that remove spikes are called spike pullers.

C.5    Rail supports

Chairs. [A form of clip]

Cross section of early T rail, chair and key

C.5.1…The 1800s: The earliest rail chairs, made of cast iron and introduced around 1800, were used to fix and support cast-iron rails at their ends. Also, they were also used to join adjacent rails.

In the 1830s rolled T-shaped (or single-flanged T parallel rail) and I-shaped (or double-flanged T parallel or bullhead) rails were introduced; both required cast-iron chairs to support them. Originally, iron keys were used to wedge the rail into the vertical parallel jaws of the chair; these were superseded by entirely wooden keys. The wooden keys were formed from oak, steam softened and then compressed with hydraulic presses and stored in a drying house. When inserted into the chair, exposure to the wet atmosphere caused the key to expand, firmly holding the rail. The wedge may be on the inside or outside of the rail.

In Britain they were usually on the outside.

Chairs have been fixed to the sleeper using wooden spikes (trenails), screws, fang-bolts or spikes.

In most of the world, flat-bottomed rail and baseplates became the standard. However, in Britain, [historically, the home of the train concept], bullhead rail-and-chairs remained in use until the middle of the twentieth century. They are now largely obsolete but can still be found on the London Underground, some sidings and at London Waterloo, at Platforms 1-4.

C.6.1…    Tie plates.

In use after 1900: A tie plate, baseplate or sole plate is a steel plate used on rail tracks between flanged T rail and the sleepers [also known as crossties]. The tie plate increases bearing area and holds the rail to the correct gauge. They are fastened to wooden ties by means of spikes or bolts through holes in the plate.

The part of the plate under the rail base is tapered, setting the cant [angle] of the rail, an inward rotation from the vertical. The usual slope is one in forty ( 1.4 degrees ). The top surface of the plate has one or two shoulders that fit against the edges of the base of the rail. The double-shoulder type is currently used. Older single-shoulder types were adaptable for various rail widths, with the single shoulder positioned on the outside (field side) of the rails. Most plates are slightly wider on the field side, without which the plates tend to cut more into the outsides of the tie, reducing cant angle.

Many railways use large wood screws, also called lag screws, to fasten the tie plates (or baseplates) to the railroad ties.

Tie plates came into use around the year 1900, before which time flanged T rail was spiked directly to the ties.

C.7…    Clips

A variety of different types of heavy-duty clips are used to fasten the rails to the underlying baseplate, one common one being the Pandrol fastener (Pandrol clip), named after its maker, which is shaped like a stubby paperclip. Another one is the Vossloh Tension Clamp.

The newer Pandrol fastclip is applied at right angles to the rail. Because the clip is captive, it has to be installed at the time of manufacture of the concrete sleeper.

C.8…    Rail anchors.

Rail anchors or anticreepers are spring steel clips that attach to the underside of the rail baseplate and bear against the sides of the sleepers to prevent longitudinal movement of the rail, either from changes in temperature or through vibration.

 

 

    In recent years, wooden railroad ties have also become popular for gardening and landscaping, both in creating retaining walls and raised-bed gardens, and sometimes for building steps as well. Traditionally, the ties sold for this purpose are decommissioned ties taken from rail lines when replaced with new ties, and their lifespan is often limited due to rot. Some entrepreneurs sell new ties.

 Due to the presence of wood preservatives such as coal tar, creosote, salts of heavy metals; railroad ties introduce an extra element of soil pollution into gardens and are avoided by many property owners. In the UK, new oak beams of the same size as standard railroad ties, but not treated with dangerous chemicals, are now available specifically for garden construction. They are about twice the price of the recycled product. In some places, railroad ties have been used in the construction of homes, particularly among those with lower incomes, especially near railroad tracks, including railroad employees. They are also used as cribbing for docks and boathouses.

 

   1991: Legal limits-Germany: Use of wooden railroad ties as building material (namely in gardens, houses and in all places where regular contact to human skin would be likely, in all areas frequented by children and in all areas associated with the production or handling of food in any way) has been prohibited by law since 1991 because they pose a significant risk to health and environment. From 1991 to 2002, this was regulated by the Teerölverordnung (Carbolineum By-law), and since 2002 has been regulated by The Chemicals Prohibition By-law.

D...Ballast-less tracks.

Ballast-less track.

Slab track, System "Rheda 2000", prior to concrete pouring

rack, System "FF Bögl" on Nuremberg-Munich high-speed rail line.

Slab track at St Pancras station

Ballast-less track does not require underlying ballast to maintain its integrity. The first such tracks were used for mountain railways (such as the Pilatus Railway, built in 1889), with the rails being attached directly to the mountain rock. From the late 1960s onwards, German, British, Swiss and Japanese railways experimented with alternatives to the traditional railroad tie, in an effort to create track with greater accuracy and longevity, along with lower maintenance costs.

    This gave rise to the ballast-less railway track, especially in tunnels, on high-speed railway lines, and on lines where high train frequency imposes greater stress on the track. Paved concrete track has the rail fastened directly to a concrete slab about half a meter thick, without ties. A similar but less expensive alternative is to accurately position concrete ties and then pour a concrete slab between and around them. This method is called "cast-in precast sleeper track".

    These systems offer the advantage of superior stability and almost complete absence of deformation. Ballast-less track systems incur significantly lower maintenance costs compared to ballasted track. Due to the absence of any ballast, damage by flying ballast is eliminated, something that occurs at speeds in excess of 250 km/h (150 mph). It is also useful in renovating existing railroad tunnels. Because slab track allows shallower construction than ballasted track, it may provide the extra overhead clearance necessary for converting a line to overhead electrification or allow the passage of trains with a greater loading gauge.

    Building a slab track is more expensive than building traditional ballasted track, which has slowed its introduction outside of high-speed rail lines. Slab track is also difficult to modify after it has been installed, and the curing time of concrete makes it difficult to convert an existing, busy railway line to a ballast-less set-up.

 Terrorism and extreme weather:

    Another, modern issue is terrorism.  Certainly, the use of a ballast-less understrata is a good preventive measure against any terrorist activity. Long and sealed concrete slabs are less likely to be tampered with by terrorists, young kids on a prank and even difficult weather conditions. 

    In Israel, that has had a fair share of terrorist events; is a good candidate for the ballast-less track. It is relatively easy to find an explosive on a slab track rather than on a ballasted track where it is easy to be hidden.

 Earthquakes: There is very little research material available dealing with a ballast vs. a ballast-less track in minor earthquakes. In theory; an engineer can conclude that a concrete slab under tracks maybe more stable in a [minor] earthquake, rather than loose ballast-stones that would move easily.

 Noise and vibration:   Slab track can also generate significantly more noise pollution and cause more vibration than traditional ballasted track. While this is partly attributable to slab track's decreased sound absorption qualities, a more significant factor is that slab track typically uses softer rail fasteners to provide vertical compliance similar to ballasted track, and these can lead to more noise, because they permit the rail to vibrate over a greater length.

    Where it is critical to reduce noise and vibration, the concrete slab can be supported on soft resilient bearings. This configuration, called "floating slab track", is expensive and requires more depth or height in the track structure, but it can reduce noise and vibration by around 80%. GERB-a commercial company, quote up to 35-40dB of attenuation using their steel sprung system.

    Alternatively, the rail can be supported along its length by an elastic material; when combined with a smaller rail section, this can provide a significant noise reduction over traditional ballasted track.

   It is obvious that railway lines in urban areas will be forced to seek better noise and vibration reductions to satisfy the local residents. New technologies with plastics, elastic materials and sensors that ‘deal’ with noise, vibrations and less wear, will year by year be introduced.

A comment: As governments, and the railroad management(s) realist that they have to upgrade their busy rail corridors [e.g. The Washington- Boston corridor, or the California/San-Francisco rectangle, or London to the North], the logistic of replacing the existing lines with high-speed components while the trains have to continue to run; becomes a nightmare. A simple example is the difficult decision-making process that Congress and the Amtrak management had to make to improve the essential train services in the NE corner of the USA. The horrendous costs involved were a significant factor. The essential crisis was; in order to reduce the insane number of local flights that crisscross the 40 airports in this region.

    In many big economies, e.g. the USA, Europe and China, train technology and especially the requirement of low maintance will continue to evolve, and  cost-factors will force new and swift application.  Moving goods and passengers in many countries by train, semi-trailer or by air will be a constantly adjusted challenge to each branch and competition will be constant.

   Steve Sattler

July 2018

Comments welcome, Dave Klepper