From February to April 2014, Transportation Technology Center, Inc. (TTCI) performed research and testing on a broken rim detector concept by Diesel Intellect International (DII). The detector uses proximity sensors to detect the presence of rim material overhanging the field side of the rail. The concept was tested with both ultrasonic and magnetic sensors. Initial feasibility was carried out using ultrasonic sensors, but it was unsuitable for the railroad environment. The device with magnetic sensors did not reliably detect a 0.75-inch deep by 4-inch long gouge on the corner of the wheel rim. The wheel position influenced by hunting and tread wear causes greater deviation in the signal than the calibration notch. The device configuration using magnetic sensors is unsuitable for broken rim detection.