The present invention relates to an improved railway track (‘rail’) or rail section on which trains run and/or are carried.

Although the following description refers exclusively to improvements in flat bottom rails (vignole) for railway networks, the person skilled in the art will appreciate that the current invention could be applied to non-flat bottomed rails.

Conventional rail or railway track is constructed from steel. The baseline for all steels is an alloy of iron and carbon which has been developed and further developed over decades through addition of various elements to realise increasing versatility of properties for a wide range of applications. Although the generic shape of flat bottom rails (vignole) for railway networks has remained broadly similar for well over hundred years, the ever increasing demands resulting from higher axle loads, vehicle speeds, and traffic density has necessitated modifications to selected key dimensions to achieve higher structural strength. This linear trend is apparent in the strong influence of rail height and section weight on the section stiffness as shown in Figures 1 and 2.

Rail sections in use today have and continue to serve the industry well. Although there has always been a keen focus on reducing costs, continued and projected increases in traffic and axle loads have put renewed pressures to further reduce cost of track maintenance and renewal through application of technologies to enhance asset life.

Running steel wheels on steel rails give rise to very demanding contact conditions that cause degradation of both mating components even in the best maintained railways. In the case of rail, the key degradation mechanisms that consume rail life are: Wear. This is an unavoidable degradation mechanism associated with the harsh contact conditions that the two mating components are subjected to . The rate at which this mode of degradation occurs has been greatly reduced through improved design and management of rail/wheel profiles, friction/lubrication conditions, and the use of steel grades that are more resistant to wear by virtue of their composition and/or the finer microstructure achieved through heat treatment. Nevertheless, effectiveness of such measures is limited by the imposition of a limit of the magnitude of permissible vertical and side wear at which the section is deemed to be incapable of supporting the passing vehicles safely. Thus, enhancing rail life despite the occurrence of wear continues to be a challenge facing the industry.

tolling Contact Fatigue·. Rails are subjected to cyclic loading in service and the magnitude and range of the stresses experienced is dependent on a range of variables including rail and wheel profiles, contact patch position and size, and the dynamic track forces from the vehicle. Consequently, the phenomenon of fatigue is of critical importance to longevity of rails. Fatigue in rails manifests itself in many ways (e.g. "squats " , "studs", "belgrospies","head checks", "gauge corner cracking", "shelling", and "spalling") and affects all rail steels in current use. Furthermore, although optimal choice of rail steel grades coupled with the desired rail/wheel profiles prolongs rail life, the two most commonly deployed remedial actions against rolling contact fatigue are rail grinding or milling both of which also consume rail life because of the enforced removal of material.

Corrugation·. Rails are prone to develop quasi-sinusoidal irregularities, which are known as corrugation and are a result of a localised variation in the magnitude of wear and plastic deformation. Although considerable research has helped to develop an understanding of the phenomenon, this rail surface damage mechanism remains endemic particularly in tramway and metro networks. Again, the two most commonly deployed remedial actions are rail grinding and milling both of which also consume tail life because of the enforced removal of material.

Plastic Deformation'. European railway networks are primarily designed for passenger traffic and the passage of freight vehicles at much lower speeds results in non-optimal contact conditions leading to increased loading on the low rail and the consequent plastic deformation of the rail head. Such damage can promote crack development and is generally removed by rail grinding.

It is apparent that the management of the key degradation mechanisms encountered on the current state of the rail section involves rail grinding and/or milling both of which consume rail life to ensure the safety of rails.

It is therefore an object of the present invention to provide an improved rail for use on a railway system that addresses the abovementioned problems .

It is a further object of the present invention is to produce an improved rail which has an increased expected life span.

It is a yet further aim of the present invention to provide a rail which:

Permits a greater magnitude of wear before the safety threshold is reached

Has the potential for more grinding or milling to be undertaken to keep rail free from Rolling Contact Fatigue (RCF) ;

Reduction in the susceptibility to RCF;

Reduction in the susceptibility to failures from the foot of the rail; and

Increase the vertical, lateral and torsional stiffness of the rail to deliver improved load redistribution over the track length.

In a first aspect of the invention there is provided a rail section comprising a head section, a foot section and a web section connecting the head section to the foot section, wherein the head section height or depth, as a percentage (%) of the total rail section height is at least 38 %.

Preferably the head section height or depth, as a percentage (%) of the total rail section height is greater than or equal to 40 %.

Typically the head section height or depth, as a percentage (%) of the total rail section height is substantially 40-48 %.

In a second aspect of the invention there is provided a rail section comprising a head section, a foot section and a web section connecting the head section to the foot section, wherein the head section height or depth is at least 60 mm. Typically the head section height or depth is 70-80 mm.

In one embodiment of the invention head section cross sectional areas of the rail profiles disclosed in European Standard EN13674 and/or American Standards (AREMA) are increased by at least 25 %. Typically the cross sectional head areas of the EN13674 profiles are increased by 25-50 %. Preferably the head section cross sectional area of the EN 1 3674 profiles and/ or American AREMA profiles are increased by 50 %.

Typically the moment of inertia (Ixx) of currently available rail section is below 4000 even for those in use in heavy haul railways. Further typically the moment of inertia (Ixx) is substantially 3000- 4000. In one embodiment the moment of inertia is substantially 3500. In another embodiment the moment of inertia is 3975, which could be increased to substantially 4500 for heavy haul rail sections.

In one embodiment the cross-sectional area of the rail foot section of the EN13674 rails is increased by at least 25%. Preferably the cross-sectional area of the rail foot is increased by substantially 50% when compared to reference rail profile as per EN13674

Typically the cross sectional area of the foot section is increased by around 25-50% when compared to reference section rail profile as per EN13674.

Further typically the cross sectional area and/or height of the web section is decreased in comparison to rail profiles as per EN13674. Further typically the cross sectional area and/or height of the web section is decreased in order to accommodate the increases in cross sectional area and or height of the head section and/or foot section, without increasing the overall height of the rail section.

In a third aspect of the invention there is provided a rail section comprising a head section, a foot section and a web section connecting the head section to the foot section, wherein the distribution of material amongst the head section, web section, and the foot section is such that the cross-sectional area of the head section is increased by at least 25% compared to a reference section 60E2 or 56E1 rail profile as per EN1 3674- 1 :201 1 .

Preferably the head section cross sectional area is increased by 50% compared to the reference section 60E2 or 56E1 rail profile as per EN13674-1 :2011.

Typically the increase in cross-sectional area of the head section is achieved by increasing only the head height. Further typically the width and/or the slope o f the head section is maintained and/or is substantially identical to the reference section 60E2 rail profile as per EN13674-1 :201 1 . The reference section 60E2 rail profile as per EN13674-E201 1 has the following dimensions or specification, also shown in figure 5 :

Typically the cross sectional area of the head section is increased by around 25-50% when compared to reference section 60E2 rail profile as per EN13674-1 :201 1 .

In one embodiment in which the cross-sectional area of the rail foot is increased by at least 25% compared to the reference section 60E2 rail profile as per EN13674-1 :201 1 .

Preferably the cross-sectional area of the rail foot is increased by substantially 50% when compared to reference section 60E2 rail profile as per EN13674-1 :201 1

Typically the cross sectional area of the foot section is increased by around 25-50% when compared to reference section 60E2 rail profile as per EN13674-1 :201 E Further typically the cross sectional area and/or height of the web section is decreased in comparison to reference section 60E2 rail profile as per EN13674- 1 :2011. Further typically the cross sectional area and/or height of the web section is decreased in order to accommodate the increases in cross sectional area and or height of the head section and/or foot section.

In a further aspect of the invention there is provided a modified or improved rail section 60E2, 60E1 or substantially similar said section including a head section, a foot section and a web section connecting the head section to the foot section and having a vignole and/or a rail profile substantially as per EN13674, wherein the height and/or cross sectional area of the head section and/or foot section is increased by 25-50%.

Typically the height and/or cross sectional area of the head section and/or foot section is increased by at least 25%. Further typically the height and/or cross sectional area of the head section and/or foot section is increased by up to and including 50%.

In a preferred embodiment the cross sectional area or profile area of the rail head section is increased by around 60 %. In one embodiment the cross sectional area or profile area of the rail head section is increased from substantially 3062 mm ² to 4989 mm ² .

In one embodiment the cross sectional area or profile area of the rail foot section is increased by substantially 40 %. In one embodiment the cross sectional area or profile area of the rail foot section is increased from substantially 2856 mm ² to 3939 mm ² .

In one embodiment the web section cross sectional area or profile area of the rail foot section is decreased by substantially 35 %. In one embodiment the cross sectional area or profile area of the rail foot section is decreased from substantially 1730 mm ² to 1 1 1 8 mm ² Typically which the tips of the rail foot have been maintained at a design that is compatible with current rail fastening systems.

In one embodiment the rail section has a second moment of area (I _xx ) value of substantially 3000-4000.

In one embodiment the rail section has a second moment of area (I _xx ) value of 3477 cm ⁴ . Typically the section has a second moment of area (I _xx ) value of which is over 15% greater than the reference section 60E2 rail profile as per EN13674-1 :201 1. Further typically this increase is reflected in a desirable reduction in the outer fibre stresses in the foot.

In one embodiment the location of the neutral fibre axis is substantially maintained at a balanced distance between the top and bottom surface of the rail. Typically the neutral fibre axis is substantially maintained at a balanced distance between the top and bottom surface of the rail by virtue of the distribution of material between the rail head and foot.

In a further aspect of the invention there is provided a rail section including a head section, a foot section and a web section connecting the head section wherein the height of the head section is 63-77 mm.

Preferably the height of the head section is substantially 76.5 mm. Typically the width of the head section is substantially 72 mm. Further typically the profile or shape of the running or top-most surface of the rail conforms to that of 60E2 rail sections.

Typically the rail section height is substantially 1 72 mm. Further typically the total height of the rail section is substantially the same as 60E2 rail profile as per EN 13674-1 :201 1. In one embodiment the height of the foot section is substantially 38— 47 mm. Preferably the height of the foot section is 42.3 mm. Typically the width of the foot section is substantially 1 50 mm.

In one embodiment the height of the web section is substantially 53.2 mm.

Typically the shape of the section components conforms to 60E2 rail profile shapes (60E2 rail profile as per EN13674- 1 :201 1) . Further typically the head section and/or foot section heights are increased whilst the web section height is decreased to accommodate the increase the head and/or foot section height, whilst the overall rail height is constant. In one embodiment the overall rail section height is 172 mm.

In a preferred embodiment of the invention the section is a flat bottomed and/or vignole section.

In a yet further aspect of the invention there is provided a rail track formed from two or more rails sections, said sections including a head member, a foot member and a web member connecting the head member to the foot member and having a rail profile substantially as per EN13674- 1 :201 1 , wherein the height and/or cross sectional area of the head member and/or foot member is increased by 25-50%.

Specific embodiment of the invention are now described with reference to the following figures wherein:

Figure 1 is a graph plotting rail section height against moment of inertia (Ixx);

Figure 2 is a plot of the influence of rail section weight on magnitude of Ixx; Figure 3 is a plot of the subdivision of head, web, and foot area as a function of Ixx;

Figures 4a and 4b are cross sectional views of rail sections;

Figure 5 is a cross section view with dimensions of a preferred embodiment of the invention;

Figure 6 is a cross section view comparison of 60E2 profile with a section in accordance with a preferred embodiment of the invention;

Figure 7 is a plot of Neutral Axis Position as % of Rail Height against Head Area;

Figure 8 is a plot of the effect of wear on outer fibre stress of rail foot for straight track;

Figure 9 is a plot of the effect of wear on outer fibre stress of rail foot for curved track;

Figure 10 is a plot of the effect of wear on ballast settlement rate for plain line;

Figure 1 1 is a plot of the effect of wear on ballast settlement rate - plain line with dipped joint;

Figure 12 is a plot of the relationship between Ixx and the Combined Area of Rail Head and Foot;

Figure 13 is a plot of the relationship between Ixx and the rail head height as a % of the total rail area; and

Figure 14 is a plot of the relationship between Ixx and the rail head height in mm. The invention provides an innovative rail profile to double life expectancy in track and improve safety. This invention concerns a rail section profile to reduce the rate of degradation of rail and track bed and significantly extend their expected in-service life span.

The relationship shown incorporates data for all rail profiles included in European Specifications for heavy rail (EN 13674-1 :201 1) and several older sections included in British Standard and several rail sections included in North American standard. The data clearly indicates the development trend in rail profile to satisfy the need for increased stiffness i. e. through increases in rail height and weight. Furthermore, it is also apparent from Figure 3, that despite the different functional contributions of the rail head, web, and foot, their proportional distribution of area has remained broadly similar. Thus, it can be concluded that the state of the art for rail section development to date has followed the trends and rules established by the very early flat bottom rail sections.

The invention will now be described with reference to the following non-limiting examples .

The invention involves the design of a flat bottom (vignole) rail profile in which the distribution of material in the head, web, and foot sections of the rail profile have been redefined to bring about very significant benefits to in-service performance including a doubling of the expected life span of the rail. A 60kg rail profile that is the most widely used in mixed traffic railway networks throughout the world has been used as the benchmark profile for the comparative assessments presented here, although the principle of the improved distribution of head, web, and foot area established as presented, is equally applicable to other rail sections in use today. To facilitate the proposed redistribution of cross sectional area, the rail profile has been sub-divided into the logical sections of the head, web, and foot as shown in Figure 4 together with the scope of the proposed parametric assessments of the modifications proposed. Although the results of these parametric assessments are summarised in Table 1 , the justification of the expected benefits, as discussed in the following examples, are with reference to most preferred developed section.

A fully dimensioned drawing of the most preferred developed section is shown in Figure 5 and a summary comparison of the key dimensional attributes with the corresponding benchmark 60E2 section is given in Table 1 The salient attributes and the benefits they support are discussed below.

In comparison to the reference profile of 60E2, the height of the rail head section has been increased from 51mm to 76.5mm while maintaining the same head width, rail height, web thickness, foot width, and details of the crown profile and upper fishing surfaces as shown in Figure 6. This increase in head height corresponds to a — 63% increase in the cross-sectional area of the head compared to the reference section. The second key modification that is apparent from Figure 3 is that the foot cross sectional area has been increased from 2856 mm2 to 3939 mm2 equating to an increase of —38%. In contrast and in accordance with the results of the parametric assessments shown in Table 1 , the thickness of the web has been kept the same as the reference section and since the overall rail height has also been left unaltered, the result has been to reduce the web cross sectional area of the most preferred design compared to the reference section by just over 35%. This largely cancels the increase in the cross- sectional area of the foot and restricts the increase in the cross- sectional area of the whole rail to just over 31 % that is predominantly concentrated in the head section which is the active part dictating performance and life span.

Another important attribute of the most preferred design of the rail is with reference to the foot section. As shown in Figure 5, the material in the foot section has been concentrated in around the central area adjacent to the web with the shape of the lower fishing surface similar to the reference section to facilitate the use of fishplates and insulated block joints . In addition, the design permits the deployment of the current designs of fastening by maintaining the thickness and shape close to the tip similar to current reference section.

A further attribute of most preferred section is the location of the neutral fibre axis which is maintained at a balanced distance between the top and bottom surface of the rail where the higher bending stresses occur. This has been done by balanced distribution of material between the rail head and foot. Figure 7 shows the achieved position of neutral axis with respect to the rail head area. The overall rail height has been maintained identical to current reference section, while concentrating material into the rail head to enhance life that is additive to any benefits from developments such as improved rail metallurgy.

A further design feature of the most preferred section is its ability to be relatively easily joined to the existing reference section using conventional welding techniques with minimal machining to produce a matching rail end profile.

The attributes described above are physical design differences when compared to the reference section and to the generic features of other rail sections in current use. The more important differentiations become apparent from the assessment of the impacts on the key performance indicators of rail life, susceptibility to rolling contact fatigue, susceptibility to failures from the rail foot, retention of track quality, and reduction in reduced noise and ground borne vibration.

Running steel wheels on steel rails give rise to very demanding contact conditions that cause wear and degradation of both mating components even in the best maintained railways. Consequently, with continued wear, the load carrying capability of the rail is reduced until a wear threshold assigned by the railways is reached and the rail has to be replaced. Thus, increasing the height of the head to 76.5mm, as in the case of most preferred section, is a constructive input of design to increase the wear threshold to higher values. However, the magnitude of this increase also needs to be based on the increase in section stiffness and the resultant decrease in the outer fibre stress at the base of the foot for a given applied loading. This assessment has been undertaken employing the numerical example of a ballasted track subjected to bogie loadings detailed in Table 2. The results of the assessment of outer fibre stress for the reference and the most preferred sections at different levels of wear and for loading conditions pertinent to straight and curved track are shown in Table 3 and Figures 8 and 9. The benefits of the most preferred section even at high levels of wear are apparent.

Table 3 Effect of rail wear on Outer Fibre Stress in Rail Foot

Another dominant rail degradation mechanism that has plagued railway networks is rolling contact fatigue. Optimisation of wheel and rail profiles to minimise the damaging stresses and the use of regular grinding/milling to maintain the desired profiles and remove damaged surface layers has become the proven method of control for rolling contact fatigue. However, both rail milling or grinding are best regarded as enforced wear that reduce the section height available for natural wear through the passage of traffic. Thus, the availability of increased rail head height, as in the most preferred profile of this invention, will permit a greater number of rail grinding/milling cycles to combat rolling contact fatigue and thereby provide increased life of rail.

One manifestation of rolling contact fatigue is the formation of discrete defects such as Squats and Belgrospies. Although the precise mechanisms of the formation of such defects remains a subject of debate and continued research, there is a school of thought that promotes the use of softer rail steel grades to increase the rate of wear and thereby remove the incipient cracks that grow into such defects . The downside of this approach is the higher rate of wear of the softer rail steel leading to shorter rail lives and more frequent replacement. The increased height of the rail head offered by the most preferred profile of this invention offers a means to claw back the disadvantages of increased rate of wear of the softer grade by providing a much deeper rail head that is available for consumption through wear before the safety threshold is reached!

Although rail milling and grinding offer very effective mitigation measures for rolling contact fatigue, one key object of this invention is to design the section profile to reduce the susceptibility to fatigue. The top layers of any rail section experience a stress range between the highly compressive stresses when the wheel is directly over a given point to a slightly tensile stress when at the peak of the bow wave. Repeated cyclic loading within such a stress range is likely to affect the growth of incipient cracks generated by ratchetting. The increased material in the head of the developed rail profile counters this degradation mechanism by reducing the stress range experienced in the top layers. Results of the numerical simulations undertaken to demonstrate this reduction in the stress range experienced are shown in Table 4 for rails in the unworn condition and with maximum permissible level of wear. The assessment has been undertaken for two loading scenarios (see Table 2) representing straight and curved track. In the case of straight track only vertical load is applied while vertical and lateral loads are applied to simulate curved track. The lower stress range experienced by the most preferred section of this invention is apparent and, of particular note, is the 20% lower stress range even with 150% additional wear under curved track loading.

Safety is normally regarded as number 1 priority in all railways and breaks in rails are a major safety concern. The mitigation action undertaken is ultrasonic and eddy current inspections supplemented by visual track walking inspection to permit the detection of rail defects before they result in complete fracture. However, current inspection techniques cannot detect defects at the base of the foot of the rail and this is reflected in rail break statistics of many railway networks that show that rail breaks caused by defects in the foot of the rail can be as high as a third of all types of rail breaks in the network. The most preferred profile of this invention provides a mitigation measure against this rail failure mechanism by reducing the magnitude of rail foot stresses resulting from the bending of the rail under the wheel. Table 3 and Figures 8 and 9 show the relationship between wear and the maximum outer fibre stress in the rail foot for various levels of wear for the two load cases described above. The most preferred profile of this invention with the current maximum permis sible level of wear (14 mm) experiences lower levels of outer fibre stress than the reference section with the same magnitude of wear and only reaches comparable levels of outer fibre stress when a further 14 mm of wear has occurred i.e. a 100% increase in the permissible level of wear. The simulation results in Table 3 indicate a greater advantage under the loading conditions in curved track.

Consistency of track support stiffness and its longevity with passing traffic are a key requirement to reduce the rate of track degradation and ensure smooth ride quality for passenger traffic. The most preferred profile of this invention has much higher vertical, lateral and torsional stiffness than the reference rail which provide benefits in several areas. One apparent benefit of the increase of vertical stiffness of the rail is in the significant improved load redistribution over the track length leading to reduced ballast pressure and sleeper accelerations, which are expected to deliver reduced rates of ballast migration and degradation of support stiffness . This advantage would be carried through into sections with different magnitudes of wear. Two scenarios have been considered in order to assess the impact of the developed profile on the dynamic track loads, i.e. plain line without vertical irregularities and plain line with a dipped joint. Figures 10 and 1 1 show how the developed profile can remarkably reduce the settlement rate in both scenarios analysed. The settlement rate has been calculated according to the Sato’ settlement law, which explicitly takes into account the bending properties of the rail section and the sleeper accelerations. It is apparent that, for the first track case, the developed rail profile maintains lower levels of settlement compared to the reference rail (60E2) for all levels of rail wear considered.

The independent aspects of the invention are:

A rail section profile comprising a head section, a foot section and a web section connecting the head section to the foot section, wherein the distribution of material amongst the head section, web section, and the foot section has been modified such that the cross-sectional area of the head section is increased by at least 25% and most desirably by 50% compared to the reference section 60E2 rail profile as per EN13674- 1 :201 1. This increase in cross-sectional area has been achieved by increasing just the head height while maintaining the width and the slope of the head section identical to the reference section 60E2 rail profile as per EN13674-1 :201 1.

A section profile according to the above in which the cross-sectional area of the rail foot is increased by at least 25% and most desirably by 50% compared to the reference section 60E2 rail profile as per EN13674-1 :2011.

A section profile according to the above and Figure 5 in which the distribution of area amongst the head, web, and foot of the rail has been modified as is apparent from the comparison with the reference section 60E2 shown in Table 5.

A section profile according to the above in which the tips of the rail foot have been maintained at a design that is compatible with current rail fastening systems .

A section profile according to the above which has a second moment of area (Ixx) value of 3477 cm ⁴ for the most preferred section which is over 15% greater than the reference section 60E2 rail profile as per EN13674-1 :201 1 . This increase is reflected in a desirable reduction in the outer fibre stresses in the foot as shown in Figures 4 and 5.

A section profile according to the above in which the relationship between the second moment of inertia (Ixx) and the sum of the area of the head and foot for the historical and current rail sections has been very significantly deviated by the most preferred section which shows just over 50% increase in the combined area of the head and the foot for the same second moment of inertia. This attribute is depicted in Figure 12.

A section profile according to the above in which the location of the neutral fibre axis is maintained at a balanced distance between the top and bottom surface of the rail by virtue of the distribution of material between the rail head and foot.

Figures 13 and 14 show graphs which use Moment of Inertia, Ixx, as the assessment criterion against rail head height either as the absolute value or as % of the total rail height. Both graphs show all rail sections included in EN13674 and the major North American rail sections as a comparison. Two examples of the innovative rail sections (Example 1 and 2 are based on 56E1 and 60E2 profiles, respectively) which demonstrates that the essence of the innovation can be applied to all rail sections in use today.

It is apparent that when compared to the EN rail sections, the innovative sections provide much greater magnitude of the wear limits while at the same time increasing the stiffness of the rail

The examples cited demonstrated that the increased stiffness demanded by heavier axle loads that characterise American railroads can be achieved with much improved capacity for rail wear and the resulting increase in rail life. Although the use of increased rail head area, as cited in the patent document, reveals the same benefit, it is possible that the availability of greater wear capacity because of the increased depth of the rail head makes a more direct impact. The influence of the modifications to the rail foot stresses are not shown.