“…However, the chain‐drag method tends to be time‐consuming, subjective, and inconsistent, and furthermore has been shown to be less accurate for detecting near‐surface delamination than the impact‐echo (IE) test method (Oh et al., ). Although sensor network‐based structural health monitoring (Hu et al., ), optical visualization techniques (Nishikawa et al., ), infrared thermography (Fuchs and Washer, ), and electromagnetic nondestructive test methods (Belli et al., ) have recently been applied to characterize concrete bridge structures, IE still is widely considered as the most effective and accurate nondestructive test technique for detection of delaminations in concrete structures (Gucunski et al., ).…”