The railroad track is continuously under force impact from trains in the long-term harsh natural environment. The mechanical wear on the railway line is gradually increasing, and the geometric dimensions of the track, ballast, subgrade and are gradually deformed. Especially the large damage to the track structure and its parts, causing serious railroad track deformation. Therefore, it is particularly important to repair and maintain railroad track.
The purpose of railroad track repair and maintenance is to find diseases and potential hidden dangers through inspecting the railway line and find out the causes. Then take measures to eliminate or reduce the effects of the diseases as much as possible. By doing so, the railway lines are kept in good condition for uninterrupted, safely and smoothly running.
Common problems in a railroad track
- Rail creep
When the train wheels run along the rails, vertical force, lateral force, and longitudinal horizontal force are generated. The longitudinal force causes the rail to move longitudinally along the sleepers. This phenomenon is called rail creep.
- Rail damage
Rail damage is mainly referred to as the uneven surface of the rails. The changes in the prescribed dimensions of the track caused by railroad rail quality, design errors, construction deviation and wheel-rail effects such as vehicle load, speed, crawling, etc., are ultimately reflected as damage to the rails.
- Rail uneven welding
- Ballast imprint on rail
- Rail collapse
- Rail corrugation
- Rail surface fatigue
- Rail side wear
The rail joints are wrongly threaded up and down. One reason is that there is a height difference between the old and newly laid rails. Another reason is there is abrasion on one end of the rail joints or the loose of track bolt.
The ballast is an important part of evenly spreading the load and providing the track’s vertical and horizontal resistance and elasticity. Under the repeated action of the long-term vibration load of the train, the ballast will appear diseases such as knots, decreased elasticity, and cut into the roadbed.
Measures to repair and maintain railroad track
- The measures to prevent rail creep are mainly to increase the vertical length of the line and strengthen the anti-climbing between the sleeper and the trackbed. The method is to maintain the standard cross-section of the trackbed, ensure that the thickness of the sleeper underground ballast is sufficient, the ballast inside the sleeper is full, and the ballast shoulders at both ends of the sleeper are wide enough. Strengthen tamping, keep the track smooth, and compact the trackbed.
- The first way to deal with rail damage is rail grinding. According to maintenance experience at home and abroad, rail grinding can improve the wheel-rail contact state, and prevent the occurrence and expansion of cracks and reduce the workload of rail maintenance.
- The track bolts should reach the required torque. Use an iron or bent rail joints to correct the left and right, up and down the thread of rails. Keep the distance between two sections of rails within 8mm.
- The ballast should always be kept full, even and tidy, and should be cleaned according to the unclean condition of the trackbed. Combined with comprehensive maintenance, to maintain the elasticity of the trackbed and good drainage.
Other maintenance work
- Renovate line signs and crossing signs.
- Protect and reinforce equipment, renovate and maintain drainage ditch and subgrade.
- Renovate the geometric state of railway track, including adjusting anti-creep locking line, adjusting rail seam, smoothing line, correcting rail bottom slope, correcting gauge, correcting direction, etc.
- Regularly update and maintain the connecting parts, sleepers and rails.
Most of the maintenance and repair work of railroad track is based on periodic repairs, including key repairs and regular inspections, periodic track comprehensive maintenance, periodic track update or overhaul.
If certain sections of the railway are inspected and the track is unstable, the staff will carry out reinforcement treatment. If it is broken, then only replace the parts. There are a large number of parts in the maintenance warehouse. These parts are all section by section, and changing the track does not require too much manpower. There are special fully automatic track-changing vehicles for maintenance. Because of the strong logistical support, even if problems arise, they can be resolved in a short time. It will not affect the operation and passage of trains.
Of course, the above situation can only be adopted when the problem is relatively simple and the handling is relatively smooth. Sometimes, when workers inspect the railway, they will find some parts that cannot be replaced in time. Then they can only adopt the method of welding. Workers will perform thermite welding on the parts where the problem occurs. This method is not very difficult, and the welded objects have extremely high firmness. This method is commonly used in the majority of railways.