Plastic railroad ties improve track. Analysis and comparison of sleeper parameters and the influence on track stiffness and performance Request for pdf of the paper ABSTRACTIn the last years, plastic railway ties have made their introduction. Amongst its characteristics, plastic ties have a good damping and a high design freedom. Talking-to-the-wall/AREMA_Surcharges_On_Retaining_Walls.jpg' alt='Arema Manual For Railway Engineering Chapter 1' title='Arema Manual For Railway Engineering Chapter 1' />Note Engineering software is currently unavailable for download using Internet Explorer. Please use Chrome or Firefox instead. We are working to resolve the issue as. May 2017 1 BNSF RAILWAY COMPANY GUIDELINES FOR INDUSTRY TRACK PROJECTS Engineering Services System Design Construction 4515 Kansas Avenue Kansas. Professional Development Series Rehabilitation and Relining of Culverts. If used in the proper way, plastic ties can give improvements in the track. They should not be regarded as a substitute for wood or concrete, but use should be made of their own characteristics. Existing sleeper requirements are however applicable for wood or concrete and can hardly be seen as functional requirements suitable for the development of plastic ties. The desired track stiffness is the first parameter to define in setting requirements. A good compromise between bending stresses in the rail versus noise and vibration seems to be a target track stiffness of 5. Nmm. When making a comparison between the different sleeper materials, the target track stiffness can be reached with plastic ties, where concrete tends to be on the stiffer side and wood shows more variations. Knowing the track stiffness gives the possibility to calculate the distribution of forces over the ties. Introduction 2 900. General MUTCD CHAPTER 1A 2. Purpose of Traffic Control Devices MUTCD Section 1A. Principles of Traffic Control. Top Rail Track. Links Advanced Principles of Track Maintenance Advanced Principles of Track Maintenance takes your crewmembers to the next level. Page i The Manual on Uniform Traffic Control Devices MUTCD is approved by the Federal Highway Administrator as the National Standard in accordance with Title 23 U. S. Introduction The study of the old and largely forgotten scientific principals behind what makes trains and railroads work, is an interesting field. This page contains a list of terms, jargon, and slang used to varying degrees by railfans and railroad employees in the United States and Canada. Especially at irregularities in the track, such as bridges or viaducts, forces on ties can become high. Special attention to sleeper stiffness parameters should be given at those locations, as well to bending stiffness as to compression stiffness. The sleeper stiffness parameters are input in calculating the system stiffness. Effects of sleeper bending stiffness on track stiffness, railhead stability and ballast contact stresses are discussed. For a 2. 60. 0 mm sleeper, a 1. Nm. 2 bending stiffness seems appropriate, where for a 2. The sleeper stiffness also has effects on the strength requirements, as has the sleeper length. Where it is clear that every situation will be different, calculations have been done to give a mean value as an example. Every specific situation can be calculated accordingly. INTRODUCTIONRailway Ties have in the past been made from wood, concrete and steel. These materials have good properties, but also have their downsides. Wood has been used since the first railway track was put in place. Concrete ties are being used more than wooden ties nowadays. Concrete is however a stiff material, consequently dynamic forces and vibrations are high, which causes, for example, high wear and degradation to the ballast. Wooden ties are therefore still being used in a lot of applications where concrete is too rigid a material. Windows Updates From Website. However, when not treated with creosotes, the lifespan of a wooden sleeper is quite limited, giving high replacement costs. Within the European union creosotes will soon be banned, which are now used to give the wooden ties an acceptable life span. Also availability issues, especially for longer bearers, increases the desirability of an alternative. Tropical hardwood can do  without creosotes, but its environmental implications and availability do not make it a viable alternative for large scale application. In the last years, recycled plastic ties have made their introduction see Figure 1. Figure 1 Plastic railroad ties in track. Plastic ties are a good alternative that can give solutions for specific problems in the track. Plastic is however a material with other characteristics than wood or concrete. It should not be regarded as a substitute for wood or concrete, but its unique characteristics should be made use of. POSSIBILITIES AND LIMITATIONS OF PLASTIC TIESTo make a suitable plastic rail road tie, the material choice to get to a pricewise compatible tie should be one of the bulk plastics, most likely Polyethylene or Polypropylene. These materials have a bending stiffness and a thermal expansion coefficient, that makes them unsuitable to be used as is. Solving these issues can be done by either reinforcing them, for example with glass fibers, creating a composite tie, or by embedding reinforcing elements, such as steel or glass fiber bars, creating a hybrid railroad tie. Figure 2 shows an example of a hybrid sleeper. In this case there are 4 reinforcing metal bars in the corners of the sleeper. Figure 2 Steel reinforced KLP S tie. Ties can be made by either extrusion or injection moulding technologies. In extrusion the sleeper is formed continuously by pressing heated plastic through a die. The shape of the sleeper is therefore uniform in longitudinal direction, except for any mechanical treatments that are done afterwards. With injection moulding, the heated plastic is pressed into a mould, after which the material is cooled. The mould can have any desired shape and so can the sleeper. The pros and cons of plastics Plastic can be shaped in any desired shape. This is primarily the case for injection moulded ties. Optimization is possible, which for example can lead to see Figure 3 Reduction of material use. The ballast is partly on top of the sleeper, thereby increasing the vertical stability of the sleeper. The change in width and the profiled underside of the sleeper increases the lateral stability of the sleeper. Figure 3 Optimized railway tie shape. Plastic is a material with time dependent stiffness properties. That means that, static test outcomes should not be used one on one to predict dynamic behaviour. Testing should be done at the appropriate speed of utilization, thus measuring dynamic material properties, as is being done with railpads. There is a lot known about the time related behaviour of plastics, so interpretation of static tests is possible when material properties are available. Plastic materials have a high damping. This results in good performance in the area of sound or vibration reduction. Measurements on a steel girder bridge showed a 3 5 d. B noise reduction after replacing wooden sleepers for plastic ties of the type as in Figure 2, see Figure 4 Movares, 2. Figure 4 Sound measurements on a Steel girder bridge near Raalte in The Netherlands. The thermal expansion of plastics is too large to use as is in a sleeper normally in the range of 1. C 1. Adding glass fibers can bring the expansion rate down with about a factor 2 at maximum. A more effective solution is for example to use steel inserts, which brings down the expansion rate to the level of steel or concrete, around 1,21. C 1. This will exclude all problems, especially on bridges where the ties do not have temperature shielding by the ballast. Plastics are highly resistant against degradation from weather influences. This will in general give an advantage against wooden ties. Specific areas where wood cannot dry properly are very suitable for the use of plastic railroad ties. See for example Figure 5. Figure 5 Switch and ties built into the pavement. Plastic materials have a high flexibility. This is a disadvantage in creating the desired bending stiffness. Adding glass fibers or reinforcements or adjusting the sleeper height is needed to get the proper bending characteristics. The flexibility is an advantage in the compression of the sleeper. This compressive flexibility gives a good distribution of the wheel loading over multiple rail ties, and also high dynamic forces will be distributed more easily. The high flexibility also gives a high local pressure to the ballast under the ties. In the case of a composite sleeper, the stiffness of the sleeper is more or less the same in all directions in flow direction of the plastic somewhat higher.