Railway tracks are the lifelines of transportation networks, enabling the smooth and safe movement of trains across vast distances. Behind the scenes, various components work in harmony to ensure the functionality and integrity of these tracks. In this blog post, we will delve into the essential components of a railway track, discussing the roles and significance of rails, fastenings, sleepers, and turnouts.
Rails: The Backbone of the Track
Rails form the foundation of the railway track, providing a sturdy surface for train wheels.. Typically made of high-quality steel, rails ensure durability, strength, and resistance to wear and tear. They come in different shapes, such as flat-bottomed, bullhead, or vignole, catering to specific track requirements. Rails guide trains, distributing their weight evenly and allowing for safe and efficient travel.
The rails in railway tracks serve several important functions:
Support:
The primary function of rails is to support the weight of the train wheels and the dynamic forces that may arise during train operation. Rails are designed to withstand the heavy loads imposed by the trains, distributing the weight evenly along the track structure. This ensures stability and prevents excessive deformation or damage to the track.
Lateral Guidance:
Rails also serve to steer the wheel axles laterally, keeping the train on track. The design of the rails must account for the impacts from the wheel flanges, which are the inward-facing edges of the train wheels. Rails are chamfered to allow the conical wheels to be self-centering, reducing the risk of derailment and ensuring smooth and safe operation.
Conduction of Electrical Current:
In electrically powered trains, the rails play a crucial role in conveying the drive current to the train. The current is supplied from the overhead catenary wires and rerouted through the rails. This allows the train to draw power from the electrical system for propulsion. The rail that redirects the current is typically referred to as an return traction conductorl.
Signal Transmission:
Rails are also utilized for conveying signals about obstacles or the presence of trains on the track. By using the concept of a wheel axle short-circuiting a signal voltage between the two rails, the safety system can detect the presence of a train in a particular track section. This information is vital for maintaining safe distances between trains and for implementing signaling systems.
These functions collectively ensure the stability, safety, and efficient operation of railway tracks. Rails are engineered with specific dimensions, materials, and profiles to fulfill these requirements and form the critical backbone of railway infrastructure.
Type of rails
Vignole rails, also known as flat-bottomed rails, is the most common type of railway rails in service. They have a symmetrical vertical profile and a flat base that allows them to sit on pads or sleepers. Vignole rails come in various shapes and sizes but share these common features. They are widely used in rail networks and make up the majority of rails in service. There are several types of profiles that can be selected on the british steel website
Crane rails, visually similar to flat-bottomed rails, are used in applications different from traditional railway use. They have a symmetrical profile and a flat bottom, but their distinguishing features are their weight and thicker web. These characteristics enable crane rails to support heavy axle loads from crane vehicles. Unlike regular railway rails, crane rails are typically continuously supported and do not sit on discrete pads or sleepers.
Check rails are a special type of rail that trains do not run on top of but rather run against. They are used in areas where additional steering forces for the axles may be needed, such as sharp curves or switch and crossing points. Check rails restrain the flat back of the train wheels, directing them around curves or toward the correct route at switches and crossings.
While various rail profiles can be used as check rails, the most common section used today is the 33C1, with equivalent profiles like U69 and UIC33 depending on the specification.
Grooved rails, as the name suggests, have a groove in them. This deep and wide groove provides flangeway clearance for railway vehicles, particularly trams. Grooved rails are typically laid into road or grass areas, preventing the road surface from obstructing the path of tramway wheels. They may also be referred to as tramway rails, although tramways often include a significant portion of regular railway rails as well. Grooved rails consist of a head, web, foot, and an additional part known as the keeper or horn, which keeps the road away from the wheels and sometimes acts as a check rail.
Guard rails are used to control the path of rail vehicles when the normal guidance from the rails has failed. They are primarily found around bridges, tunnels, and other vulnerable areas where a derailment could have catastrophic consequences if the vehicle deviated from the track. Guard rails are not usually a separate rail section but rather utilize various standard rail profiles. It’s worth noting that some people in the industry also refer to check rails as guard rails, which can cause slight confusion in terminology
Fastenings: Securing the Rails
Fastenings are crucial in securing the rails to the sleepers or ties. They include a variety of components such as clips, bolts, screws, and plates. Their function is to transfer the loads from the rails to the sleepers and further to the track’s substructure, to maintain the gauge, and to prevent twisting of the rails in relation to the sleeper. The rail fastening should have the required clamping force and allow a certain freedom of movement and torsional resistance.
Fastenings ensure the stability and alignment of the track while accommodating expansion and contraction due to temperature variations. These components resist the lateral and vertical forces exerted by moving trains, maintaining the integrity of the track structure.
There are various kinds of fastenings and the old versions are being replaced by new fastening systems although old fastening types remain in use in different parts of the world. The following table presents the types of fastenings, their elasticity property condition, their positive and negative sides, and the regions of their applications.
| Type | Elasticity | Suitable for tree-sleepers | Suitable for concrete sleepers | Suitable for concrete slab | advantages | disadvantages | country |
| Railspike, without platta | No | yes | No | No | low cost and simple | easy to be loosened | worldwide |
| Railspike, with plate | No | yes | No | No | low cost and simple | easy to be loosened | worldwide |
| Tree screw, with plates | No | yes | No | No | low cost and simple | quick to be loosened | worldwide |
| Elastic spike, with plates | yes | yes | No | No | low cost and simple | fatigue | worldwide |
| K-fastening | partly | yes | yes | yes | easy to install | needs to be pulled finally | germany |
| Hambo | yes | No | yes | (not used) | very easy to install by machines | fatigue | sweden |
| Pandrol E-clip | yes | yes | yes | yes | simple and easy to install | Needs to be mounted in the bracket by hand (time consuming), easily comes off when derailed | worldwide |
| Pandrol Fastclip | yes | No | yes | yes | simple,easy to install, installed on sleepes on delivery | Insulators may break | worldwide |
| W-fastening | yes | yes | yes | yes | stress can be controlled | Complicated (many parts) | germany,norway |
| Nabla | yes | No | yes | No | (inga uppenbara) | Complicated | france |
| Fist | yes | No | yes | No | — | Difficult to inspect, cracks | sweden |
Hey back.
Heyback fastening is a Norwegian invention designed to provide secure and reliable fastening for railway tracks. It consists of a washer plate that is screwed into the sleeper and a clamp made of spring steel that tightly holds the rail foot against the plate. This innovative fastening system can be used on both wooden sleepers and concrete sleepers, offering versatility in track installations.
The primary purpose of Heyback fastening is to meet the demanding requirements of seamless tracks, particularly in terms of holding power, rail travel, and torsional resistance. Its implementation began on selected main lines in the mid-1950s, showcasing its effectiveness and reliability in rail infrastructure.
In the Heyback fastening system, the base plate is securely held in place within the sleeper using four rail screws. To ensure proper alignment and cushioning, a 3.5 mm thick rubber spacer is inserted between the rail foot and the base plate. The rail is then firmly fixed to the base plate with the help of clamping springs, which are wrapped between strips on the upper side of the plate.
The Heyback fastening system has proven to be a valuable addition to railway track components, offering stability, durability, and resistance to various forces exerted on the rail. It is efficient design and secure installation make it a reliable choice for maintaining the integrity of railway tracks and ensuring safe and smooth train operations.
Rail spike
Rail spike fastening is an essential component of railway track systems used to secure the rails to the sleepers or ties. The forces transmitted from the rails to the ballast, including those from rolling stock, rail movement, and temperature changes, can act vertically, laterally, and along the rails simultaneously. To counteract these forces, the rail fastening system must provide the necessary clamping force, ensuring a strong connection between the rails and sleepers while resisting rail travel and twisting.
Over time, the design of rail fastenings has evolved from simple spike fasteners on wooden sleepers to more advanced systems on concrete sleepers. Initially, rail spikes were widely used to attach rails directly to the sleepers, often accompanied by steel underlay plates placed between the rail foot and the sleeper. As rail traffic increased, it became apparent that additional reinforcement was necessary. The dimensions of the underlay plates were gradually increased to enhance the stability and durability of the fastening system.
Rail spike fastening, which includes rail spikes and underlay plates, offers a straightforward and cost-effective solution. It is relatively easy to assemble and disassemble, and in freezing conditions, it can be supplemented with wedge plates or wedges. However, rail spike fastening does have some drawbacks. The holding power of the spikes is sometimes insufficient, resulting in movement between the rail components. This can lead to mechanical wear and an increase in track width. Moreover, the resistance to rail travel provided by rail spike fastening may not be adequate, necessitating the use of additional precautionary measures.
In summary, rail spike fastening systems play a vital role in ensuring the stability and integrity of railway tracks. While rail nail fastening on wooden sleepers has been a widely used method, the development of more advanced fastening systems has introduced improved performance and reliability, addressing the challenges posed by various forces and conditions encountered in rail transportation.
Elastic spike with plates:
The elastic rail spike is a type of fastening system used to secure rails, base plates, and sleepers in railway tracks. It consists of three spring nails that are driven into pre-drilled holes in the sleepers.
The diameter of the holes varies depending on the type of sleeper, with pine sleepers typically having a diameter of 13 mm and beech sleepers having a diameter of 15.5 mm.
In a healthy sleeper, each nail exerts a holding force of approximately 5 kN, resulting in a total holding force of approximately 15 kN when three nails are used per plate.
However, over time, the attachment of the nails in the sleeper deteriorates, leading to a decrease in holding power and increased rail travel resistance.
To mitigate these issues, a 3.5 mm thick rubber spacer is placed between the rail foot and the base plate. Previously, wood fiber spacers were used, but the rubber spacer offers increased friction between the rail and the base plate. This helps to maintain stability and reduce rail movement.
It’s important to note that the use of spring spikes is not recommended in tracks that experience freeze-ups requiring wedging.
Additionally, the repeated process of pulling out and hammering down the nails can further deteriorate the nail attachment and reduce the holding power over time.
Overall, the elastic rail spike provides a method for securely fastening rails, base plates, and sleepers in railway tracks, ensuring stability and reducing rail travel resistance.
K-fastening:
The K-fastening system is a widely used and classic screw fastening method employed on railway lines, particularly on wooden sleepers. It provides a reliable connection between the sleeper and the plate.
The K-type fastening system requires the installation of an under-base pad beneath the ribbed plate, while a rail seat pad is placed under the rail foot. The rail is secured using the clip, ensuring proper fixation.
One of the notable features of the K-fastening system is its versatility, as it can be mounted on prestressed concrete sleepers as well. This flexibility allows for its application in various railway infrastructure projects.
The system offers effective insulation between the rail foot and the sleeper, contributing to electrical and thermal insulation properties, which are essential in ensuring safe and efficient railway operations.
The components of a K-fastening system typically include rail clamps, rail screws, T bolts with washers and nuts, a tie plate, and dowels. These components work together to provide a robust and secure connection between the rail and the sleeper, contributing to the overall stability and longevity of the railway track.
Overall, the K-fastening system is a time-tested and reliable method used in railway construction worldwide. Its versatility, insulation properties, and availability of different clip options make it suitable for a wide range of railway applications.
Hambo:
The Hambo fastening is a railway fastening system that was originally developed in Sweden. It was created by combining the names of its inventors, Hammerin and Borup, resulting in the name “Hambo.” Although it was once widely used, particularly in the early 2000s, it has gradually fallen out of favor and is no longer extensively utilized.
The fastening consists of two hooks, which are attached to monolith slips or one-block sleepers. Each hook holds a smaller hook that secures the rail in place. Positioned between the rails and sleepers is an underlay plate made of insulating material, which serves as a buffer. This plate helps to provide insulation and prevent electrical conductivity between the rail and the sleeper.
The fastening system is designed to provide stability and secure the rail in place. The hooks, made of elastic steel, are cast into the sleeper, ensuring a durable and robust connection. A plastic spacer, approximately 5.5 mm thick, is placed between the hooks. This spacer has raised side strips on which the rail foot rests, offering additional support and preventing lateral movement.
Overall, the Hambo fastening is a Swedish innovation that was once commonly used in railway construction. Its unique design, incorporating hooks, spring links, and an insulating underlay plate, provided a secure and stable connection between the rail and sleeper. However, its usage has declined over time, likely due to the emergence of alternative fastening systems that offer improved features or cost-effectiveness.
Pandrol E-clip:
The E-clip fastening system is a resilient method of connecting railway tracks to sleepers, ensuring stability and accommodating rail movement. It consists of several components that work together to provide a secure and flexible connection.
At the core of the system is a backing plate with a loop that holds the E-clip in place. The E-clip, similar to a paperclip, exerts pressure against a plastic spacer on the upper side of the rail foot. This pressure, which can be as high as 1000 kp (1 ton), ensures a firm grip between the rail and the fastening system. To provide cushioning and insulation, a rubber spacer is placed beneath the rail foot.
When it comes to detaching the E-clip, it can be dislodged by applying force, such as with a sledgehammer. The E-clip is typically made of round spring steel and is available in different diameters to accommodate various applications. Coarser clips, often green, are used for attaching gears, while straight grooves are secured with finer clips, often red.
The installation of E-clip fastenings differs depending on the type of sleepers used. For wooden sleepers, the backing plate is secured with wood screws and spring washers. In the case of concrete sleepers, a simplified plate is precast into the sleeper during manufacturing.
The advantages of the Pandrol E-clip fastening system are numerous. It offers excellent vibration absorption, reducing stress and wear on the rail and sleeper. The resilient connection provided by the E-clip accommodates rail movement and expansion, enhancing track stability. The system utilizes Pandrol’s original design ‘e’ shape, which has set the industry standard for fastening systems. Being a threadless, self-tensioning system, there is no need to periodically check the torque. The system is also known for its durability, minimal risk of corrosion, and ease of installation on both concrete sleepers and in combination with base plates.
Overall, the Pandrol E-clip fastening system is a reliable, globally used solution for securing railway tracks. Its simplicity, durability, and ability to accommodate rail movement make it a preferred choice for various applications, environments, and market segments.
Pandrol Fastclip:
The Pandrol Fastclip fastening system is a highly regarded and resilient rail fastening solution designed for efficient installation and long-term performance. It consists of various components, including a baseplate, pre-assembled elastic clips, and bolts or clips for fastening.
The unique feature of the Pandrol Fastclip is its ability to be pushed perpendicular to the rail, allowing it to be snapped into three different positions. In the first position, it locks against the rail foot, providing a secure connection. In the second position, it parks to facilitate rail insertion. And in the third position, it allows for insulation change.
During the manufacturing of the sleeper, all fastening details are already put in place, making installation easier and more efficient. The pre-assembled nature of the clips eliminates the need for manual assembly and reduces installation time.
One of the key advantages of Pandrol Fastclip fastenings is their ability to absorb and dampen vibrations effectively. This superior vibration absorption helps reduce wear and tear on the rail and sleeper, ensuring long-term performance even under heavy loads and various track conditions.
The fastening system offers a high level of adjustability, both vertically and laterally, allowing for precise alignment and easy maintenance. It is designed for use on various track types, including ballastless tracks, and can be adapted to different railway applications such as light rail, metro, mainline, and high-speed tracks.
Additionally, the Pandrol Fastclip system is designed to provide efficient installation and minimize maintenance costs, resulting in maximized rail infrastructure uptime. With its captive design and reliable clamping force, the Fastclip fastenings offer a robust and durable connection between the rail and sleeper, ensuring the safety and stability of the track system.
In summary, the Pandrol Fastclip fastening system is a resilient and efficient rail fastening solution that offers ease of installation, superior vibration absorption, and robust performance. Its pre-assembled nature, adjustable design, and ability to accommodate various track conditions make it a reliable choice for railway infrastructure.
W-fastening:
The W-fastening system, also known as the W System series, is a highly reliable and acknowledged “Elastic Rail Fastening System” used worldwide. It is comprised of five parts and offers exceptional performance and durability.
At the core of the W-fastening system is the W-shaped tension clamp with spring arms. These spring arms exert a constant clamping force on the rail, ensuring a secure connection to the sleeper. The rail is fastened to the sleeper using a dowel and rail screw, preventing any lateral tilting or deformation. The forces generated are effectively transferred to the sleeper and the ground through the angled guide plates.
One of the notable advantages of the W-fastening system is its simplicity and reliability. It is a low-maintenance system that can be installed quickly and easily. If necessary, all parts of the fastening system can be replaced, allowing for easy maintenance and repair. Additionally, the W-fastening system is suitable for use with elastic rail pads, further enhancing its performance and reducing vibrations.
The W-fastening system is designed to withstand heavy loads, with a resistance capacity of up to 22.5 tons of axle load. This makes it suitable for demanding applications such as heavy haul and high-speed railways. It has been extensively tested and proven in various conditions, including severe curves, wide temperature fluctuations, and heavy carloads.
In North America, Vossloh’s W System series offers a modern solution for ballasted concrete ties. The system utilizes the shoulders of the concrete tie to provide stability to the track and fastening system. This ensures efficient force transfer and minimizes structure-borne noise caused by passing trains. The W-fastening system has been successfully implemented in over 30 countries, covering a combined total of 1,900 track miles.
For conventional speeds, the W 21 is the ideal choice and has been widely adopted globally. It has a proven track record in various railway networks and is suitable for speeds typically found in standard operations. On the other hand, the W 21 HS variant, designed for high-speed applications, has been successfully tested at speeds of up to 155 mph, making it suitable for high-speed rail systems.
For heavy haul operations, the premier choice is the W 40 elastic rail fastening system. It is specifically designed to withstand extremely heavy carloads and maintain maximum stability, even in narrow bends and tight curves. The W 40 system has been successfully in service in North America since 2013 and has been installed on approximately 200 track miles.
Overall, the W-fastening system offers a reliable, low-maintenance, and versatile solution for various railway applications, meeting the rigorous standards and demands of modern rail networks.
Nabla:
The Nabla fastening system, specifically the NABLA Evolution, is a highly efficient direct rail fastening system designed to deliver superior performance, particularly in tracks with tight radius curves. With a proven track record spanning several decades, it is recognized for its ease of installation and maintenance, making it a reliable choice for rail networks.
The components of the nabla fastening system constitute of a nabla clip, rail insulator, screw spike, nut and spring washer.
One of the key advantages of the NABLA Evolution is its ability to maintain the track gauge, which significantly enhances the longevity of the assembly components. This feature ensures the stability and integrity of the track, leading to improved operational efficiency and reduced maintenance requirements.
The NABLA Evolution fastening system is suitable for a wide range of track types, including heavy haul applications. It offers not only improved electrical insulation but also exceptional lateral force absorption. The lateral insulator, which incorporates glass-reinforced material, provides enhanced mechanical strength, contributing to the system’s overall durability and reliability.
Widely used in Europe, the Nabla fastening system is renowned for its safety and reliability. It finds applications in various railway tracks, including Tram, LRT (Light Rail Transit), Metro, Main Line, and High-Speed tracks. The unique shape of the Nabla blade generates a dynamically stable toe load on the steel rails when the rail nut is torqued, ensuring secure and stable rail fastening.
In summary, the Nabla fastening system, exemplified by the NABLA Evolution, offers a robust and efficient solution for rail networks. Its proven performance, simple installation, maintenance advantages, and compatibility with different track types make it a preferred choice for ensuring safe and reliable railway operations.
Fist fastening:
The Fist Rail Fastening System is a type of railway fastening system that is designed to securely attach rails to sleepers or ties. It is a popular choice in various countries, including South America and Australia. The system consists of several components, including a spring steel clip, rail pad, and insulated retaining pin.
The spring steel clip plays a vital role in providing the necessary grip and holding the rail firmly in place. It is designed to withstand the forces and vibrations experienced by the rail, ensuring stability and preventing movement. The rail pad acts as a cushion between the rail and the sleeper, absorbing vibrations and reducing wear and tear on both components. It also helps distribute the load evenly, protecting the sleeper from excessive stress.
To ensure electrical insulation and to prevent stray currents, the Fist Rail Fastening System includes an insulated retaining pin. This pin helps maintain electrical isolation between the rail and the sleeper, ensuring safe and efficient operation of the railway.
The Fist Rail Fastening System is versatile and can be used with different types of sleepers, including wooden, steel, or concrete sleepers. It offers flexibility in terms of toe load and axle load requirements, allowing customization to suit specific railway applications.
Originally developed in Sweden, the Fist Rail Fastening System has gained popularity and is extensively used in various countries in Africa, such as South Africa, Zimbabwe, Botswana, Swaziland, and Namibia. Its reliable performance, ease of installation, and ability to withstand heavy loads and harsh track conditions make it a preferred choice in these regions.
Overall, the Fist Rail Fastening System provides a robust and resilient connection between the rail and the sleeper, ensuring track stability, vibration absorption, and electrical insulation. It is a reliable solution for securing rails in railway infrastructure, contributing to the safe and efficient operation of the railway network.
SKL fastening
The SKL rail fastening system is a type of hot rail fastening system commonly used in the railway materials market. It consists of several components, including SKL rail clips, rail pads, screw spikes, tie plates, washers, plastic dowels, track bolts, and nuts.
One specific type within the SKL rail fastening system is the SKL-12 rail fastening system, which is typically used in ballastless tracks without concrete retaining shoulders. Its main structural features are as follows:
- Separate screw holes: The ribbed plates have separate screw holes at both ends, which are connected to the railway sleeper/track plate using fork bolts.
- T-bolt insert seat and retaining shoulder: The ribbed plate is equipped with a T-bolt insert seat and retaining shoulder. The elastic clip is fixed by tightening the nut of the T-bolt.
- Horizontal and lateral adjustment: Different sizes of eccentric heart taper pins are used for horizontal and lateral adjustment of the rail.
- High and low adjustment: High and low setting plates are inserted to achieve high and low adjustment of the rail.
The SKL rail fastening system, also known as the Vossloh clip fastening system, is widely used in heavy haul, high-speed, and standard track applications. It provides stability to the track, accommodates rail movement, and offers easy maintenance. The system is cost-effective due to the absence of a base plate, and it is compatible with various types of SKL rail clips, such as SKL1, SKL3, SKL12, and SKL14.
Benefits of the SKL rail fastening system include:
- Stability: The system provides stability to the track and allows for the transfer of forces generated by passing trains.
- Easy maintenance: The screw design facilitates maintenance work and helps reduce maintenance costs.
- Cost-effectiveness: The absence of a base plate results in lower manufacturing costs.
The SKL rail fastening system is widely used in concrete sleepers on ballast tracks worldwide. It offers a permanently elastic fastening, good creep and torsion resistance, and high tilting stability. The system is designed for long service life and requires low maintenance. Different configurations and options are available, such as dual gauge and turnout sleepers, as well as theft-resistant screw heads.
KPO rail fastening
The KPO clamp rail fastening system is a widely used clamp system for railway tracks, especially for crane rails. It offers better clamping force and a longer lifespan compared to normal fastening systems. The KPO system has gained popularity worldwide due to its safety and stability performance.
The KPO fastening system includes various types of clamps, such as KPO3, KPO5, KPO6, and KPO9, which provide excellent clamping force. These clamps are designed to securely hold the rail in place while allowing necessary longitudinal movement. The KPO clamps are fastened to the rail ties using anchor bolts.
The components of the KPO rail fastening system include:
- KPO Clamp: The KPO3, KPO6, and KPO9 clamps are key components of the fastening system, providing the necessary clamping force to secure the rail.
- Screw Spike: The Ss8 screw spike is used to fasten the rail to the sleeper or tie plate.
- Rail Dowel: The Sdu9 rail dowel is used to provide additional stability and support to the rail fastening system.
- Bolt, Nut & Washer: The Hs32 bolt, nut, and washer are used for securing the various components of the fastening system.
- Rail Pad: The rail pad, according to customer specifications, is used to provide cushioning and reduce vibration between the rail and sleeper.
- Tie Plate: The tie plate is an essential component that distributes the load from the rail to the sleeper or ballast.
The KPO rail clip, also known as a rail fixing clip, is a key component of the KPO fastening system. It ensures the lateral position of the rail while allowing necessary longitudinal movement. The rail clamp features a mechanical lock that keeps the rail in position, combined with a vulcanized synthetic elastomeric nose that accommodates longitudinal rail movement. Rail clamps are typically fastened to the rail ties using anchor bolts.
The KPO rail clip is adjustable, self-blocking, and offers high clip strength. It is especially suitable for crane tracks on steel girders or concrete foundations with steel sole plates. The height of the rail clip is variable, allowing for compatibility with different rail types. It is designed to accommodate rail types ranging from 10kg/m up to 56kg/m, offering versatility in rail applications.
Overall, the KPO clamp rail fastening system provides a safe, stable, and durable solution for securing railway tracks, particularly crane rails. With its superior clamping force, longevity, and adaptability to different rail types, the KPO fastening system is widely recognized and used in railway projects around the world, especially in Europe.
Sleepers: Supporting the Rails
Sleepers, also known as ties, provide support and stability to the rails. They are rectangular blocks or beams placed transversely beneath the rails. Sleepers can be made of wood, concrete, or steel. Wood sleepers are commonly used due to their availability and cost-effectiveness, while concrete and steel sleepers offer increased durability and longevity. Sleepers absorb vibrations, reduce noise, and distribute the load evenly, enhancing the track’s strength.
Steel Sleepers:
Steel sleepers, also known as steel ties or steel railroad ties, are a type of sleeper or tie used in railway track systems. They are typically made of high-strength steel and offer a durable and long-lasting alternative to traditional wood or concrete sleepers.
Advantages:
- Durability: Steel sleepers have excellent resistance to wear, corrosion, and weathering, resulting in a longer lifespan compared to wood or concrete sleepers.
- Load-bearing capacity: Steel sleepers can handle heavy axle loads and high traffic volumes, making them suitable for high-speed and heavy-haul railway lines.
- Easy maintenance: Steel sleepers require less maintenance than wood or concrete sleepers. They do not rot or degrade over time, reducing the need for frequent replacements.
- Compatibility: Steel sleepers can be used with various rail types, making them versatile for different track configurations.
- Recyclability: Steel is a highly recyclable material, allowing for environmentally friendly disposal and reuse of steel sleepers at the end of their life cycle.
Disadvantages:
- Higher cost: Steel sleepers are generally more expensive than wood or concrete sleepers due to the higher material and manufacturing costs.
- Installation complexity: Specialized equipment and expertise are required for the installation of steel sleepers, which may increase construction time and costs.
- Thermal expansion: Steel sleepers expand and contract with temperature changes, which can cause stresses on the rail and track structure if not properly accounted for in the design and installation.
- Conductivity: Steel sleepers have high electrical conductivity, which can pose challenges in terms of electrical insulation and signaling systems.
Wooden Sleepers:
Wooden sleepers, also known as timber sleepers or ties, have been widely used in railway track systems for many years. They are typically made from hardwood or softwood and provide a traditional and cost-effective option for track infrastructure.
Advantages:
- Cost-effective: Wooden sleepers are generally less expensive than steel or concrete sleepers, making them a popular choice for low-traffic or secondary railway lines.
- Insulation: Wood has good electrical insulation properties, which can be beneficial for signaling and electrical systems on the railway.
- Easy installation: Wooden sleepers are relatively lightweight and easy to handle during installation, reducing the need for specialized equipment.
- Natural resource: Wood is a renewable resource, making wooden sleepers a more environmentally friendly option compared to non-renewable materials like steel or concrete.
Disadvantages:
- Limited lifespan: Wooden sleepers have a shorter lifespan compared to steel or concrete sleepers. They are susceptible to rot, decay, insect infestation, and weathering, requiring regular maintenance and replacements.
- Lower load-bearing capacity: Wooden sleepers have lower load-bearing capacity compared to steel or concrete sleepers, making them less suitable for high-traffic or heavy-haul railway lines.
- Vulnerability to fire: Wood is combustible, and wooden sleepers can be prone to fire hazards in case of accidents or deliberate acts.
Concrete Sleepers:
Concrete sleepers, also known as concrete ties, are made from reinforced or pre-stressed concrete and are a common choice for railway track systems worldwide.
Advantages:
- Durability: Concrete sleepers have a long lifespan and are resistant to rot, decay, weathering, and insect infestation.
- High load-bearing capacity: Concrete sleepers can support heavy axle loads and high traffic volumes, making them suitable for high-speed and heavy-haul railway lines.
- Low maintenance: Concrete sleepers require minimal maintenance compared to wooden sleepers. They do not require regular replacement due to decay or rot.
- Stability: Concrete sleepers provide excellent stability and track alignment, reducing track maintenance needs.
Disadvantages:
- Higher cost: Concrete sleepers are generally more expensive than wooden sleepers due to the higher material and manufacturing costs.
- Difficult handling: Concrete sleepers are heavy and require specialized equipment and machinery for installation and maintenance.
- Limited flexibility: Concrete sleepers have limited flexibility compared to steel or wooden sleepers, which may pose challenges in accommodating thermal expansion and contraction.
- Environmental impact: The manufacturing process of concrete sleepers has a higher carbon footprint compared to wooden or steel sleepers.
Turnouts: Directing Train Paths
Turnouts, also known as switches or points, are critical components of railway tracks that enable trains to change direction or switch between tracks. They consist of movable points, switch rails,switch devices and tie rods, allowing trains to traverse onto different tracks. Turnouts ensure smooth transitions between tracks, providing flexibility and efficient route management in complex railway networks.
Simple turnout components
A simple railway turnout, also known as a switch, consists of several key components that allow for the diversion of trains from one track to another. These components work together to guide the wheels towards either the straight or the diverging track. Here is a description of the various components involved in a simple railway turnout:
1. Points (Switch Rails or Point Blades):
Points refer to the movable rails that guide the wheels towards either the straight or the diverging track. They are tapered on most switches, but on stub switches, they have square ends. The points can be switched or moved between positions to direct the train onto the desired track.
2. Stock Rails:
Stock rails are the running rails immediately alongside the switch rails. They provide a foundation for the switch rails when they are in the closed position. The stock rails are ordinary rails that are machined, drilled, and bent as required to accommodate the design of the railway turnout switch and the individual switch point rails.
3. Frog:
The frog is a crucial component placed where one rail crosses another. It refers to the crossing point of two rails. It allows the wheels of the train to smoothly transition from one track to another. In other English-speaking countries, the term “crossings” is often used to refer to this component.
4. Closure Rails:
Closure rails are the straight or curved rails positioned between the heel of the switch and the toe of the frog. They fill the gap between these two components and maintain the continuity of the track. Closure rails ensure a smooth transition for the train as it passes through the turnout.
5. Guard Rail (Check Rail):
Guard rails, also known as check rails, are short pieces of rail placed alongside the main (stock) rail, opposite the frog. Their purpose is to ensure that the wheels follow the appropriate flangeway through the frog. Guard rails prevent the train from derailing by guiding the wheels in the correct direction.
6. Heel Block Assemblies:
Heel block assemblies are units positioned at the heel of the switch. They provide a splice with the contiguous closure rail and offer a location for the switch point rail to pivot at a fixed spread distance from the stock rail. Heel block assemblies play a crucial role in the proper functioning and alignment of the switch.
7. Switch Point Rail Stops:
Switch point rail stops act as spacers between the switch point rail and the stock rail. They laterally support the switch point rail, preventing it from flexing under a lateral wheel load. These stops ensure that the open end of the switch point rail is not exposed to head-on contact from the next wheel, enhancing safety and reliability.
8. Switch Operating Device:
The switch operating device is responsible for moving the switch rails. It allows the points to be thrown or moved from one position to another. This device can be either hand-operated, such as a manual switch stand, or power-operated, such as a mechanically or electro-mechanically operated switch machine. The switch operating device is typically located at the beginning of the railway turnout, near the switch-connecting rods and the point of the switch rails.
Types of turnouts
There are different types of turnouts with regard to their function, geometrical profile, size, inclination, and design speed. The typical types of turnouts are Standard turnout, symmetrical turnout, diamond crossing, single slip, double slip, cross over, double cross over, and lapped turnouts. Turnouts can be classified also according to the direction the diverging tracks go in to left and right types and also to outer and inner curve turnouts depending on which direction the centers of the main and direction curves lie. Check more classifications in the Trackopedia article.
1-Standard Turnout:
A standard turnout is a commonly used railway component that allows trains to switch between two tracks. It consists of two switch rails that diverge from the main track, creating a branching path for the train to follow. The standard turnout provides a smooth transition for the train from one track to another.
2- Symmetrical Turnout:
A symmetrical turnout is a special type of turnout where the two diverging routes from the main track are symmetrically positioned. This means that the angle between the switch rails is the same on both sides. Symmetrical turnouts are often used in situations where balanced traffic flow is desired on both tracks.
3. Three-way turnout
A three-way turnout, also referred to as a three-way switch or a three-way point, is a specialized railway component that connects three tracks in a railway network. It is designed to allow trains to switch between these three tracks, providing enhanced routing options and operational flexibility.
The construction of a three-way turnout typically involves three switch rails diverging from a common point, forming a triangular configuration. This triangular arrangement enables trains to move from any one of the three tracks to the other two, facilitating seamless track switching and routing possibilities.
4- Diamond Crossing:
A diamond crossing, also known as a diamond or crossing diamond, allows two tracks to intersect each other. It consists of four rails arranged in the shape of a diamond. Trains can cross the intersection by passing over the diamond-shaped crossing point. Diamond crossings are essential for enabling trains to change tracks and navigate complex rail networks.
5- Single Slip Turnout:
A single slip turnout is a type of crossing that provides one switching possibility. It allows trains approaching on one track to either continue over the crossing or switch tracks to the other line. However, trains from the other track can only continue over the crossing and cannot switch tracks. Single slip turnouts are often used to provide access to sidings and improve safety by avoiding switch blades facing the usual direction of traffic.
6- Double Slip Turnout:
A double slip turnout, also known as a double slip, is a crossing that allows trains to change from one straight track to another while also offering the possibility of going straight across. It consists of a narrow-angled diagonal flat crossing with four pairs of points, enabling trains approaching from any direction to leave via any of the two tracks on the opposite side of the crossing. Double slip turnouts are typically used in situations where trains need to switch tracks in multiple directions.
7- Crossover:
A crossover is a railway component that connects two parallel tracks, allowing trains to move from one track to another. It typically consists of two turnouts positioned side by side. Crossovers are commonly used when trains need to change tracks, such as during maintenance or to access different platforms in train stations.
8- Double Crossover(scissors crossing):
A double crossover, also known as a scissors crossover, is a more complex version of a crossover. It consists of two crossovers with opposite hand orientations superimposed upon each other. In addition to the four turnouts involved, a track crossing diamond is required between the two main tracks. Double crossovers provide the ability to switch from both tracks to the other in either direction when there is limited space to install a universal crossover.
9. Combinations of simple turnouts, slip turnouts, and crossings.
According to the requirements of traffic directions and capacity, the different types of turnouts can be combined to form complex turnouts. The downside is that they can result in more maintenance needs and be more expensive.
10- Lapped Turnout:
A lapped turnout is used to achieve a more compact track layout in constrained locations. In a lapped turnout, the switch rails for a second turnout are placed between the switch and the frog of the initial turnout. This introduces a third frog where a closure rail of the first turnout crosses a closure rail of the second turnout. Lapped turnouts allow for efficient use of space while still providing the necessary branching paths for trains to switch tracks.
Designation of turnouts in drawings
The established designation of a turnout identifies all relevant track technical components of a turnout and describes its operational characteristics. The turnouts are identified by assigned standard nomenclature as shown below:
EW-60-760-1:18-r-Fz-B
EW … Type of turnout
60 … Shape of rail
760 … Radius of branch
1:18.5 … Inclination of the turnout
r … Direction of branch line
Fz … Type of tongue
B … Type of sleeper