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 1. planning and experimental setup
Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured. Therefore data available from the literature have different degrees of reliability. With the aim of enlarging the knowledge on the track stability and covering much of the possible relevant scenarios, an experimental research program has been developed in the framework of a cooperation between RFI, Italcertifer and DII. In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 28 significant scenarios have been identified and reproduced on as many independent track segments. By applying on each track segment a transversal load, the strength of the ballast-sleeper interface has been determined. The results relative to the first four scenarios are presented in terms of applied load vs. lateral track displacement diagrams and in more synthetic numerical tables.
DYNAMIC BUCKLING TEST ANALYSES OF A HIGH DEGREE CWR TRACK. FINAL REPORT
Thermal buckling of railroad tracks in the lateral plane is an important problem in the design and maintenance of continuous welded rail (CWR) tracks. The work reported here is part of a major investigation carried out by the John A. Volpe National Transportation Systems Center for the Federal Railroad Administration on the thermal buckling of CWR tracks with the objective of developing guidelines and recommendations for buckling prevention. This report presents the results of two major buckling tests conducted on 7.5 degree curved CWR track at the Transportation Test Center, Pueblo, CO. In the first test, thermal buckling was induced in the absence of vehicles to evaluate the static buckling strength of the 7.5 degree curve with 1.5 in. line defect. In the second test, the dynamic buckling behavior of the curve (with typical line defects as in the revenue tracks) under vehicular traffic was studied. The buckling strength of the track under vehicle loads was determined in this test.