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[IMAGE]MET6track-plasser.jpg[/IMAGE]For the safety and comfort of passengers, the importance of track maintenance cannot be overstated. A well-maintained track results in a smoother ride, reduced wear and tear on trains, faster speeds and prevents derailments. Track degradation is caused by the day-to-day travel of trains, which can cause track instability, and can vary depending on weight placed on a track, speed, climate and various other factors.
Regular track inspection is essential in ensuring a safe track. Specialized machines are now used to do a significant amount of maintenance work, which ranges from rail testing for flaws to rebuilding damaged, worn or derailed tracks. Choosing whether to buy a track maintenance machine or to contract out a company for maintenance purposes depends on the individual needs of transit agencies.
Plasser American Corp.
Based in Chesapeake, Va., Plasser American Corp. designs and manufactures rail maintenance equipment for sale to clients.
Over time, as trains continually travel over tracks, the ballast, or rocks underneath the track become unevenly settled, resulting in what would be equivalent to potholes on street surfaces. A tamping machine fixes this problem by lifting the track and packing the ballast underneath the ties to level out the uneven surface that the track lays on.
Plasser's Metro 4x4 is one of the company's smaller tamping machines. Designed for transit agencies, the Metro 4x4 can be built in different configurations and is used by Boston's Massachusetts Bay Transportation Authority, Metropolitan Transportation Authority's New York City Transit and Long Island RailRoad, Dallas Area Rapid Transit, Maryland Transit Administration, Toronto Transit Commission and the Port Authority Trans-Hudson. The Metro 4x4 comes standard-equipped with fully automatic, computer-controlled Automatic Geometry Guidance System (AGGS) lifting, leveling and lining systems.
During the tamping process, the ballast bed is disturbed. A dynamic track stabilizer is often used behind the tamping machine. The PTS 62 Dynamic Track Stabilizer is the largest that Plasser manufactures. Using hydraulic cylinders and vibration to force down the track, the rocks shake themselves into a compact state. The vibration and controlled vertical load create a more stable position for train traffic. The Dynamic Track Stabilizer settles the disturbed track bed in a controlled environment, thus reducing the need for slow orders and allowing trains to run across maintained track at scheduled speeds.
The PBR 550 ballast regulator brings ballast that has flowed out from the track section back into it. This improves the appearance of the track and keeps the track in place. The outward flow of ballast is caused by trains over the track, but weather conditions and temperature can affect ballast movement as well. Regulating typically comes after tamping, or, if a stabilizer is used, the process comes after stabilizing.
Track recording cars ride along the track and take geometry measurements of its cross-level, surface or alignment. The latest of its kind is the TGC 04, which is specially designed for a transit railway, and can be fitted with a multitude of measuring and recording functions that include a GPS locator; rail flaw detection system to locate defects inside the rail; and a clearance measuring system that measures the track in relationship to platform edges, tunnel walls, etc.
The type of track recording car used depends on what the customer is looking to measure, and each machine can be fitted with the function needed. NYC Transit recently purchased one of the most multi-functioned vehicles that Plasser American makes.
Equipment size can vary and reach lengths of several hundred feet, but the equipment mentioned above can stretch to more than 56 feet in length. Machines are always stored on side tracks, maintenance yards or buildings and their maintenance depends on usage. Regular oil checks and air filter changes are necessary, as are monthly and annual checks.
According to Plasser, the cycles for track maintenance vary greatly based on climate, tonnage, speed and track usage, and can range from three times a year to once every several years, depending on each railroad's maintenance guidelines.