Effect of Wheel/Rail Loads on Concrete Tie Stresses and Rail Rollover

Abstract

As a result of vertical and lateral wheel/rail forces, high contact stresses can develop at the interface between the rail base and tie. Under certain conditions, these stresses can exceed the strength of the concrete tie and result in deterioration of the tie and ultimately derailment due to rail rollover. This failure mode has been determined to be the probable cause of at least two derailments where the ties were found to have a triangular wear pattern. Following these derailments, a field investigation revealed this pattern of failure present in an appreciable portion of concrete ties [1]. Closed-form analyses have been conducted to examine combinations of wheel/rail loads and contact conditions that produce concrete tie rail seat deterioration or rail rollover. These results indicate that under certain circumstances truck-side L/V permitted by the Federal Railroad Administration (FRA) Safety Criterion on Wheel/Rail Loads can result in stresses above the AREMA specified minimum design compressive strength of concrete used in concrete ties. Furthermore the analysis indicated that under certain circumstances truck-side L/V permitted by the FRA Safety Criterion can result in rail rollover. The analyses show that rail rollover can be a problem for new concrete ties, but is more of a problem in the presence of rail seat deterioration described above. This work is sponsored by FRA Office of Research and Development under the track research program.