Director Track Maintenance – Technology

Research activity currently sponsored by the Association of American Railroads and carried out by Transportation Technology Center, Inc. (TTCI) in conjunction with Kandrew, Inc. Consulting Services has focused on improving the performance of continuous welded rail (CWR) track through enhanced rail neutral temperature (RNT) maintenance practices. One issue being investigated is the process of restoring RNT that has been lowered when the rail is cut or broken at temperatures below the rail’s existing RNT. Readjustment of the RNT is accomplished by restoring the tension that was lost when the rail broke or was cut. This loss of tension is evident by the rail gap that is created at the break/cut location and it influences the rail over some distance each side of the gap. Ideally, the rail in this influence zone will be unfastened and the RNT brought back to a desired condition during the readjustment process. However, influence zone lengths can be long, requiring substantial time and resources for unfastening and RNT readjustment. This paper presents an approach where RNT readjustment lengths can be reduced without compromising the safety of CWR track. This optimized readjustment length is based on allowing a pocket of decreased RNT to remain in the influence zone that is compensated for by overstressing at the location where the rail broke or was cut. It is expected that this uneven readjusted RNT profile will be equalized by subsequent train traffic.