Ultrasonic Guided Waves-Based Monitoring of Rail Head: Laboratory and Field Tests

Table 4

Defect detection reliability during March 2008 field test at Gettysburg, PA.

Defect	Surface cut (5% H.A)	Surface cut (2% H.A)	Internal defect; (gage side, 3.6% H.A.)	Internal defect; (gage side, 35% H.A.)	Oblique cut (3.5% H.A.)	Internal defect; (center head, 12% H.A.)	Oblique cut (3.5% H.A.)
Position from start	81^′_7^′′	82^′_7.5^′′	86^′_4^′′	91^′_3.5^′′	95^′_1^′′	96^′_4^′′	97^′_8^′′	False positive %
POD (5 MPH)	100	97.7	100	81.8	95.5	84.1	100	0.8
POD (10 MPH)	100	100	100	100	75	87.5	100	2.9
POD (Cumulative)	100	98.1	100	84.6	92.3	84.6	100	1.1