This report highlights research conducted to determine the remaining (residual) prestress force in prestressed concrete ties that had performed well in track and were subsequently removed after 25 years of service. The team developed a new, direct tension test method to experimentally determine the residual prestress force in a concrete tie. The method used the entire tie as the test specimen rather than extrapolating the data from the response of one component, or region of the tie. This new approach minimized the effect of small measurement errors.