The Interchange Rules of the Association of American Railroads (AAR) limit the life of freight cars to 50 years from the date originally built. Recently, however, the AAR has instituted a new provision under Interchange Rule 88 that permits cars to operate for up to 65 years since their built date. The procedure incorporates two basic portions; demonstrating that the carbody has the structural integrity to last for a total life of 65 years and upgrading specific components on each car. After applying to the AAR Equipment Engineering Committee (EEC) requesting that ILS be granted to a particular group of cars, the car owner has two optional methods to demonstrate the structural integrity of the selected cars. The first option is to perform structural inspections on a specified number of representative cars and to perform a full-scale fatigue test on a test car. In place of the fatigue test, the second option is to perform structural inspections on a larger number of cars and conduct follow-up inspections every five years after receipt of approval. The physical fatigue test incorporates modern engineering best practices by utilizing finite element modeling and full-scale accelerated fatigue testing (AFT). Following the creation of a representative model, several load conditions, both real and worst-case, are then applied to determine the high-stress locations. Using instrumentation at the high-stress locations, a full-scale test is conducted with the car operating in a typical service environment. The objective of full-scale testing is to obtain real strain data and input loads produced by typical environment conditions. AFT enables the required load cycles to be applied to the test car in a dynamic test fixture in weeks or months versus years of actual service. A rapid accumulation of fatigue-damaging cycles representative of the remaining years necessary to bring the total life of the test car to 65 years are applied to the car. The requirements for the components to be replaced or upgraded under Rule 88 are similar to those for new cars and for rebuilt cars. Some components, such as air brake control valves, are to be upgraded to more recent standards. Others are to be replaced in kind with reconditioned parts. Even though the carbody is permitted to operate beyond 50 years, components must still comply with existing AAR and Federal Railroad Administration (FRA) age limits. In addition to obtaining Increased Life Status (ILS) from the AAR, the car owner must also apply to the Federal Railroad Administration for authorization to operate the cars beyond the 50-year limit of the FRA Freight Car Safety Standards. This paper will demonstrate the approval process, including AFT testing, as applied to two groups of flat cars in auto rack service, and a group of 60-foot flat cars.

Federal Railroad Administration, Title 49, Code of Federal Regulations, Part 215 “Railroad Freight Car Safety Standards,” § 215.203.
Association of American Railroads, 2005 Office Manual of the AAR Interchange Rules, Pueblo, CO, pp. 11–31, 2005.
The Welding Institute Research Bulletin, Vol. 17, May, 1976.
Association of American Railroads, Manual of Standards and Recommended Practices, 1994, Section C- Part II, Volume 1, Specification M-1001, Section 7.4, Table 7.4.2.
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