US. Department of Transportation Federal Railroad Administration Determination of Dynamic Fracture Toughness Properties of Rail Steels __ - LZ£ 224jA Office of Research and Development Washington DC 20590 M.F. Kanninen R.J. Dexter J.W. Cardinal Southwest Research Institute Engineering and Materials Sciences Division San Antonio TX 78284 DOT/FRA/ORD-87/08 November 1987 DOT-TSC-FRA-87-3 Final Report This document is available to the Public through the National Technical Information Service, Springfield, Virginia 22161. Track ez Structures