United States Department of Transportation
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Edition:Final Report June 28, 1974 to July 31, 1976
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Abstract:This report has been prepared by the FRA as an overview of work accomplished by the Southern Pacific Transportation Company for FRA. It represents the first of a six-volume published set. The other five volumes are listed at the end of this Abstract. The primary objective of TDOP Phase I was to evaluate the dynamic performance of the conventional three-piece friction-snubbed freight car truck (Type I) and to identify design modifications that improve ride quality, reduce maintenance, and increase railroad profitability. Spanning from 1974 to 1976, the study encompassed analytical modeling, field testing, and economic evaluation. Key project activities included development of performance models, execution of tests assessing lateral stability, vertical dynamics, roll behavior, and curve negotiation, and formulation of preliminary performance and testing specifications. Findings emphasized the significant impact of wheel profile, truck design features (e.g., centerplate friction, side bearing pressure), and component wear on lateral hunting, ride comfort, and curving performance. While certain modifications improved specific performance metrics, trade-offs were noted—such as increased lateral stability at the cost of curve negotiability. The report concludes that although TDOP Phase I delivered valuable data, limitations such as lack of theoretical integration and insufficient performance-economics linkage hindered full utility. Recommendations for future research in TDOP Phase II include broader validation, industry engagement on performance standards, and investigation into wheel profile optimization. The remaining five main volumes of Phase I are:
(1) Vol. II - Phase I Final Report, FRA/ORD-78/12.II
(2) Vol. Ill - Phase I Frequency Domain Model, FRA/ORD-78/12.Ill
(3) Vol. IV - Critique of Frequency Domain Model - Solution Techniques, FRA/ORD-78/12.IV
(4) Vol. V - Critique of Frequency Domain Model - Equations of Motion, FRA/ORD-78/12.V
(5) Vol. VI - Critique of Phase I - Test Series Results Reports, FRA/ORD-78/12 .VI
Also available in microfiche or photocopy form from NTIS:
(1) Vol. VII - Results Report for Test Series 1, FRA/ORD-78/12.VII
(2) Vol. VIII - Results Report for Test Series 2 and 5, FRA/ORD-78/12.VIII
(3) Vol. IX - Results Report for Test Series 4, FRA/ORD-78/12.IX
(4) Vol. X - Results Report for Test Series 3 and 5, FRA/ORD-78/12.X
(5) Vol. XI - Performance Guidelines for Type I Trucks FRA/ORD-78/12.XI
(6) Vol. XII - TDOP Postprocessing Program Manual, FRA/ORD-78/12.XII
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