Let's hit the rails
April 2, 2022
Early rails were made of wood, cast iron or wrought iron. Modern rails are hot rolled steel with a cross section approximate to an I-beam. The top of the rail is profiled to resist wear and to give a good smooth ride, and the foot profiled to suit the fixing system.
Unlike some other uses of iron and steel, railway rails are subject to very high stress and are made of very high-quality steel. It took many decades to improve the quality of the materials and changing from iron to steel. Minor flaws in the steel may pose no problems in other applications but can lead to broken rails and dangerous derailments when used on tracks. The heavier the rails and the rest of the track work, the heavier and faster the trains that tracks can carry.
Rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by steelworks at one time, so a railway must choose the nearest suitable size. Worn, heavy rail from a mainline is often reclaimed and downgraded for re-use on a branch line, siding or storage yard.
CWR, Continuous Welded Rails, refers to the way in which rail is joined to form track. CWR, rails are welded together to form one uninterrupted rail that may be several miles long. Although CWR is normally one continuous rail, it may contain joints for one or more reasons, such as insulated joints that electrically separate track segments for signaling purposes. Over the decades driven by legislative mandates together with knowledge gathered from the industry, the CWR regulations have expanded. Today railroads are required to adopt and comply with CWR programs that cover procedures for installing, adjusting, inspecting and maintaining CWR, as well as inspecting joints in CWR track.
Rail joints, usually called fishplate, commonly known as the joint bar, is a component that joint rails end-to-end and is used in both light rail, and heavy rail. There are holes in the middle of the fish plate for rail bolt to screw. The top and bottom of the fish plate are made into slopes corresponding to the slope of the lower part of the railhead and the top part of the rail bottom. The design which helps the joint bars wedge the rails, the rail joints can be bolted to the rail very tightly. Good rail joints can reduce the impact of wheels at the joint and improve the smoothness of the passing trains.
The railroad tie sometimes called a sleeper or crosstie is an easily overlooked component of railway tracks. The sleepers not only support the rail but also maintain the position of the rail. It helps to transmit the huge pressure by rail to the track bed. It is required to have a certain degree of flexibility and elasticity. It can't be too hard or too soft. When the train passes by, it can be properly deformed to cushion the pressure. But, it has to be restored as much as possible. In the early days, railroad ties are made of wood while prestressed concrete is more common to see now. Sometimes plastic composite ties are also applied.
Fasteners are used for fixing rails to railway sleepers. It is also a very important component of railway track. Most commonly seen fasteners include spikes, screws, rail anchors, tie plates, chairs, etc. Various types of fasteners have been used over the years. Other track materials like rail clip, rail clamp, rail pad, rail joints also belong to railway fastening systems.
Fasteners effectively guarantee the reliable connection between rail and rail, rail and sleeper and maintain the continuity and integrity of the rail. They also prevent the horizontal and vertical movement of the steel rail relative to the sleeper, ensure the normal gauge is maintained.
The fasteners exert the buffering and vibration reduction performance under the power of the locomotive and vehicle to delay the accumulation of residual deformation of the line.