An Investigation of the Practicability of Testing Steel Rails by Electrical Methods

The finding of hidden flaws or defects in rails has been given considerable attention. In our thesis, we undertook to find out if flaws could be detected by means of a change in the resistance of the rail. In our investigations, we assumed that flaws in rails could be considered under two heads; namely, longitudinal flaws and transverse flaws. We did not consider it possible to detect longitudinal flaws or cracks, as the stream lines of the electric current flowing through the rail would pass through the metal surrounding the longitudinal flaw, without any appreciable lengthening of the path of the current, hence without any increase in the resistance of the material. From talks with railroad men, it would also appear that longitudinal defects were not considered to be as serious a menace as transverse flaws. We learned that when a longitudinal flaw was detected, the rail was not immediately replaced, but merely watched and replaced only when, in the opinion of the track foreman, the defect was serious enough to endanger the trains.