Wheel impact load detectors (WILD) effectively find out-of-round and shelled wheels, but by design, these detectors are not meant to find wheels with internal cracks that may lead to breaks. In fact, many broken wheels fail without ever indicating WILD-recorded high impact loads. Other vision- or laser-based systems can only find broken wheels after they fail. These systems are not designed to find internal fatigue cracks that are believed to be the precursor of broken wheels. Rails are tested ultrasonically for internal defects; currently, wheels are not tested in the same manner. The goal of the ACWDS is the safe detection of wheels with internal defects without interrupting revenue service.
Read the full article at Railway Age.