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 explore the essential components of a railway track, discussing the roles and significance of rails, fastenings, sleepers, and turnouts.
Railway lines consist of various systems that work in harmony to effectively transport goods and people from place to place. The backbone of the railway system is the railway tracks. The other important systems are, notably, the power systems, the signal system, and the telecommunication systems.
The construction process of railway tracks
Before railway tracks are laid, the ground—referred to as the railway formation—must be carefully prepared to support the loads from the tracks and trains, and to protect the infrastructure from surface runoff and groundwater.
This preparation involves designing and constructing a stable foundation using well-engineered soils and materials that provide adequate support beneath the tracks.
The formation must also be constructed with appropriate vertical and horizontal alignment—geometric configurations that ensure safe and comfortable movement for trains and passengers.
Once the subgrade meets the necessary strength, drainage, and alignment requirements, the track structure can be installed.
A typical railway track consists of the following main components:
- Rails
- Fastenings and sleepers
- Ballast and
- Turnouts (switches) are also included where directional changes are needed.
Rails: The Backbone of the Track
Rails form the core of the railway track system, providing a strong and stable surface for train wheels to travel on. They guide the movement of trains and help evenly distribute the loads to the underlying track foundation. Typically made from high-grade steel, rails are designed for durability, high strength, and resistance to wear and deformation over time.
Beyond their structural role, rails also serve critical electrical and safety functions. In electrically powered rail systems, they act as conductors providing a return path by routing it back through the rails to complete the electrical circuit required to power the train.
Rails are also an essential component of railway signaling systems. They can detect the presence of a train on a given section of track through a method known as track circuiting, where the metal wheels and axles of a train short-circuit a low-voltage signal between the two rails.
This detection is used to send signals about train locations and potential obstacles, helping to prevent collisions and maintain safe separation between trains.
Various types of rails exist, each tailored to specific applications. The most common is the Vignole rail, widely used in mainline railway systems. Grooved rails are typically used in tram systems embedded in roadways to allow for smooth vehicle and pedestrian crossings. Other types include crane rails used in industrial facilities for heavy lifting, and guard rails and check rails, which are specialized components used at track switches and crossings to guide train wheels and ensure safe directional changes
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 about the sleepers. 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.
As the railways have evolved from wooden sleepers to stronger concrete sleepers, the fastening systems have also modernised. The spike systems famous with wood sleepers are now replaced by Eclips and Fast clips with the modern concrete sleepers.
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 most common fastenings being used worldwide are Eclips, fastclips. The most common old types of fastenings are rail spikes and tree screws, which are still widely used in heritage railways.
There are also specific types of fastenings that are used only in some countries like Sweden, Germany, and China.
The following are the common types of fastenings that are used in the railway industry.
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 displacement 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.
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.
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 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.
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.
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 electromechanically 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. sleeper
Republished on August 7, 2025