MxV Rail has been investigating the causes and potential mitigations for broken spikes that can occur on curved track. Instrumented spikes were developed and used in revenue service and at the Facility for Accelerated Service Testing (FAST®), Pueblo, CO, to measure the spike loading environment. The revenue service site featured trains with various weights and types. The FAST® test used different wood tie fastening systems. Using the measured spike load level under different conditions, a fatigue analysis was performed to estimate when spike breakage would occur. During the FAST® test, instrumented spikes were installed on four commonly used fastening systems. In the revenue service test, the spike load level was measured based on train passage with a variety of axle loads, providing real-world loading environments for spikes. A rainflow-counting algorithm was used to calculate the stress cycle amplitude and cycle count for the spike fatigue analysis. This analysis showed that…