Contaminants on the wheel of a railcar can have an adverse impact on the railcars themselves. One location where it can be particularly dangerous is in hump yards, where buildup of contaminants can reduce the effectiveness of retarders, which are used to slow down railcars being gravity-fed over a "hump" into the classification yard. 

Michigan Tech investigated designs for a sensor to search for these contaminants, which would alert yard operators and potentially allow corrective action to be taken. 

This project was sponsored by Norfolk Southern Corp and the NURail Center