Laboratory Characterization of Structural Capacity of North American Heavy Haul Concrete Crossties

Abstract

Over the past few decades, the use of concrete crossties in North America has increased as a high-performance alternative to timber crossties, especially in heavy-haul freight and higher speed rail corridors. To accommodate heavier axle-loads and prevent center cracking, railroads and suppliers have consistently increased the bending moment thresholds that a crosstie must withstand, leading to stiffer elements that may be more prone to brittle cracking. This paper attempts to characterize the structural capacity of the crosstie at two critical design locations, the center and the rail seat cross sections. Concrete crossties were subjected to four-point bending tests at both the center and rail seat, while recording corresponding deflections using protocols adapted from the American Railway Engineering and Maintenance-of-Way Association (AREMA) Manual on Railway Engineering. Experimentation was performed on some of the most representative concrete crosstie designs that are currently installed in North America, with 70 individual crossties undergoing tests. The resulting load-deflection curves illustrate the variability of each crosstie’s response to load and characterize the flexural performance of the crossties. Results showed that North American crosstie designs frequently have significant reserve capacity and high stiffness. The results also indicate that even severely abraded crossties can have enough flexural capacity to withstand typical field loading conditions.