Minor problems with the performance of some track components have been noted in Northeast Corridor concrete-tie track. Performance-related events have been caused primarily by short-duration impact loads due to wheel tread or rail running surface roughness. To reduce these occurrences, remedial projects were initiated by Amtrak. These included the development of a wheel impact load detector (WILD) to identify specific impact load-producing wheelsets, field tests of more resilient tie pads, use of a different rail slip design, repair of engine burns, etc. This report provides an assessment of these remedial projects.
Four test sites were chosen for detailed track walker surveys to define the condition of NEC concrete-tie track. Four surveys on six-month intervals were conducted over each of the sites, a total of 19 miles of track. Component event codes from the surveys were stored in a data management system that allowed analysis of performance issues and correlation with rail anomalies (joints, battered welds, etc.). Little tendency toward clustering of events was found, and the track was generally in excellent condition.
The WILD detector system was used bot to develop wheel load statistics and to identify passing Amtrak wheelsets developing high impact loads. A wheel truing program was initiated by Amtrak, using the WILD as an inspection tool, that quickly eliminated extreme loads and reduced rough tread conditions. Measured loads and wheel profiles were used to develop and validate a vehicle/track component dynamic response to impact loads using a calibrated drop hammer.