RISK ANALYSIS BASED CWR TRACK BUCKLING SAFETY EVALUATIONS.
As part of the Federal Railroad Administration’s (FRA) track systems research program, the US DOT’ Volpe Center is conducting analytic and experimental investigations to evaluate track lateral strength and stability limits for improved safety and performance. This paper deals with a part of this research addressing the development of a comprehensive CWR buckling safety analysis which includes a risk analysis based approach for prediction of probable number of buckles on a given track. These risk based buckling evaluations are particularly useful for dealing with statistical variability in the track parameters. The risk approach can provide economic options for track maintenance to achieve the desirable buckling strength. The buckling risk methodology and the statistical parametric descriptors are discussed and a buckling risk analysis model is presented with illustrative examples. The model also provides a computational scheme for the determination of buckling probability as a function of maximum rail temperature when the key influencing parameters of track lateral resistance, lateral alignment defect and rail neutral temperature are given as statistical variables. The risk based approach as well as the previously developed deterministic approaches in CWR-BUCKLE and CWR-INDY are all being integrated in a single new computer program called CWR-SAFE. CWR-SAFE is a Windows based software analysis package for a comprehensive buckling safety evaluation for use by both the railroad industry and the research community.
Transverse strength of railway tracks: part 3. Multiple scenarios test field
In the present paper the design and construction choices of a test field for the ballast lateral resistance measurement, in order to produce data useful for the development of a numerical model able to simulate the service critical conditions of a continuous welded rail track, are described. Some construction details described herein allow to better understand the methodological approach followed in the design of experiments, the tests management philosophy as well as of the accuracy achieved in their implementation.
PARAMETRIC STUDIES ON LATERAL STABILITY OF WELDED RAIL TRACK
Thermal buckling of railroad tracks in the lateral plane is an important problem in the design and maintenance of continuous welded rails (CWR). The severity of the problem is manifested through the increasing number of derailments which are attributable to track buckling, indicating a need for developing better control on the allowable safe temperature increase for CWR track. The work reported here is part of a major investigation conducted by the Transportation Systems Center for the Federal Railroad Administration, on the analytical predictions of critical buckling loads and temperatures, and deals with a parametric investigation of the buckling response of CWR track. Buckling temperature and safe allowable temperature increase values are predicted for both tangent and curved tracks, as influenced by several key parameters, including track lateral and longitudinal resistances, lateral misalignments and rail size. Results of sensitivity analyses over a practical range of the parameters are presented and a suitable design criterion to ensure stability of CWR is outlined.