Railroad crossties have been made almost exclusively of wood from the beginning of the railroad age. The wooden crossties are held in place by ballast rock, and the rails are attached using tie plates and cut spikes. This is a readily available and commonly used system. The wooden ties accept and hold spikes, so that the rail and tie plate fastening systems may be secured to the ties. A wood tie will flex under load. The resulting flexing is beneficial only in that it helps to provide for a softer ride. However, the flexing also increases the displacement of, or "pumpinpg" of, the supporting ballast out and away from the tie. This increases maintenance cost. The flexing also "pumps" or works the spikes up and loosens them, resulting in additional maintenance cost. Wooden ties deteriorate and must be replaced at regular intervals, resulting in high maintenance costs.
Railroad ties made of material other than wood have been proposed. For example, U.S. Pat. No. 5,238,734 to Murray discloses a railroad tie made from a mixture of recycled tire fragments and an epoxy mixture. Other patents disclosing railroad ties made out of composite materials include U.S. Pat. No. 4,150,790 (Potter) and U.S. Pat. No. 4,083,491 (Hill). Although ties made out of composite materials provide significantly longer life than conventional wooden ties, it has not been possible to provide composite ties that are durable enough to withstand the heavy repeated loads of main line railroad tracks. Both wooden and composite railroad ties tend to pump ballast rock away from the rails, thus requiring frequent reballasting.
Concrete crossties that are reinforced with various materials are also known in the prior art, such as the crosstie disclosed in U.S. Pat. No. 1,566,550 (McWilliam). However, conventional concrete crossties are too hard and brittle to use conventional and standard fastening systems (tie plates and cut spikes). Concrete ties use pre-casted fasteners that are attached during the curing stage in the tie manufacturing process. Furthermore, each tie must be individually loaded and obstructed from the mold. The concrete crossties are stiff and non-flexible, this is advantageous and provides a stiffer track module, improved lateral stability and gauge control, increased rail life, and greater locomotive fuel economy. What should have been a significantly lower maintenance cost due to the lack of "pumping" of the ballast rock, has actually become another maintenance cost. The concrete tie is so hard that it pulverizes the ballast rock beneath it which results in a sand like or soft support system.