This project is an analysis of rail flaw data from commercial inspection systems. The experimental test work was performed at the facilities of the Transportation Technology Center Inc. (TTCI). Six major railroads provided defective rail which had been removed from service. The rail, which contained a variety of defects was placed into a gauntlet track. The gauntlet track is known as the Railflaw Detection Test Facility and is a railroad industry tool, in cooperation with the Federal Railroad Administration, to evaluate rail flaw detection technology. TTCI inspected the rail, catalogued the defects, and installed the rail in the RDTF. This series of defects was then used to test the comparative performance of commercial rail flaw detection systems. Each system had a maximum of 49 defects which had to be detected for a perfect record. To date there have been six evaluations performed at the RDTF. Preliminary data is shown which indicates the probability of detection for the flaws in the test configurations which can then form a basis for a needs assessment for rail flaw detection.