With nearly 930 million railroad crossties in service in the U.S. alone, 15 million require renewal or replacement every year. In a study sponsored by the Federal Railroad Administration (FRA), researchers at West Virginia University (Morgantown, W.Va., U.S.A.) investigated the benefits of wrapping creosote-treated wooden railroad crossties with E-glass fiberglass fabric wet out with phenolic resin, as a low-cost method to increase used tie stiffness and durability, without replacement.
According to team leader Ram Chamarthy, composite material cost is minimized by wrapping only the region directly under each rail and steel attachment plate. A wrapping machine was designed and built to wind the ties with either three or four plies of resin bath-impregnated fabric, in a hoop orientation. The end of the fabric was secured to the tie with large staples, and the composite was cured at room temperature for 48 hours (the cure time can be accelerated with the application of heat). Test results have shown that a wrapped, full-scale crosstie is up to 35 percent stronger and 14 percent stiffer than unwrapped ties. The wrapped ties also have better damping capability and higher load capacity than standard ties. Chamarthy estimates that under production conditions, ties could be rehabilitated at $20 each, compared to the cost of a new tie at about $35. Four hundred wrapped ties have undergone long term testing at the Transport Technology Center Inc. in Pueblo, Colo., U.S.A. and the South Branch Valley Rail Authority in Moorefield, W.Va., U.S.A., with no adverse performance response up to 150 million gross tons of load.