Technical Reports

Investigation on CWR Longitudinal Restraint Behavior in Winter Rail Break and Summer Destressing Operations

  • 01
  • Aug
  • 1997
AUTHOR: Federal Railroad Administration
OFFICE: RPD
SUBOFFICE: RPD-30
REPORT NUMBER: DOT/FRA/ORD-97/01
KEYWORDS: continuous welded rail; CWR; neutral temperature; destress; rail anchor; railbreak; anchor; fastener
ABSTRACT: This report presents the results of investigations on the rail anchor/fastener effects on rail movement and the resulting rail force distribution in continuous welded rail (CWR)track during rail breaks and destressing operations. Two types of tests are used, one for simulating winter rail break and another for destressing operations in summer. The winter rail break test is used to determine the size of the rail gap and the length of the disturbance zone in rail neutral temperature that occur when the rail breaks. The summer rail destressing test is used to determine the deanchored zone length and the rail length to be cut when the rail is destressed. The results are correlated with analyses. The results will be useful to the industry in optimization of their destressing operations. It is shown that the required deanchored section length depends on the precut rail force at the cut location, its distribution along the track and rail longitudinal resistance. By measuring the initial rail force and the resulting gap or longitudinal displacements at the cut locations, the deanchored length can be determined without direct measurement of the initial force distribution and the longitudinal resistance. On the basis of investigations carried out here, improved guidelines are presented for rail gap adjustment in restressing operations using rail heating or hydraulic tensioning.

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