Vertical split rim (VSR) is a serious railway wheel failure mode that requires further research. Visual clues are not usually present until the crack propagates through the rim. To better understand the root causes of VSRs, the Federal Railroad Administration (FRA) and the Association of American Railroads (AAR) have jointly funded the investigation of this problem. To better understand VSR, Transportation Technology Center, Inc. (TTCI) attempted to create this defect in a laboratory. A deep slit was cut into the tread of the wheel. After 1.8 million cycles at loads of 36–50 kips, the crack still did not propagate and no VSR was created. This test followed previous attempts of higher vertical wheel loads, but without a cut, that did not create VSR. Wheel manufacturers and TTCI previously tried to create a VSR under controlled conditions using a rolling load machine. In both previous instances, a VSR was not created.