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.
WOOD TIE TRACK RESISTANCE CHARACTERIZATION AND CORRELATIONS STUDY
The work presented here is part of a major program to evaluate lateral buckling of continuous welded rail (CWR) tracks. The program to develop the technical information to support safety guidelines and specifications for track buckling prevention is being directed by the Volpe National Transportation Systems Center in support of the Federal Railroad Administration. This report presents the results of an extensive field test and evaluation study conducted to characterize the track lateral and longitudinal resistance behavior. More than 1400 tests were conducted to measure the lateral resistance for the purpose of isolating the effects of ballast type and consolidation, crib depth, shoulder width, track curvature, and loading methodology and rate. The contribution of each of these factors is quantified and discussed. The relationship between peak and limiting lateral resistance has been evaluated, and recommendations for the required test sample size are made. Data from tests performed with the Single Tie Push Test (STPT) fixture were correlated with the data from the Track Lateral Pull Tests (TLPTs). This report also presents the results of pilot field tests conducted to measure the track longitudinal resistance. The influences of rail anchoring, ballast consolidation, and crib depth were measured, and their effects are quantified.
Physical Principles of Wind Energy Conversion
The primary component of a wind turbine is the energy converter which transforms the kinetic energy contained in the moving air, into mechanical energy. For the initial discussions of principles, the exact nature of the energy converter is irrelevant. The extraction of mechanical energy from a stream of moving air with the help of a diskshaped, rotating wind energy converter follows its own basic rules.