Reliability of crack detection for baseline condition assessments

Despite billions of dollars of annual exposure from claims and litigation related to construction-induced damage, there are no quantitatively based, agreed upon standards or procedures as to what constitutes due diligence with respect to a pre-construction, condition assessment. Similarly, the relative accuracy, reliability, and costs for various inspection approaches are not well established. This paper compares the relative performance capabilities of crack detection by sidewalk-based, manual inspection with digital photography, terrestrial Light Detection and Ranging (LiDAR), and elevated manual inspections based on 2 brick and 2 concrete buildings (8.2-14.3m high) in Dublin Ireland. Results showed that non-manual methods tended to over-predict crack widths by at least 5 mm and underestimate crack lengths by one-half. Digital photography, however, detected the shortest cracks (as short as 17 mm) and had no significant decline in accuracy beyond 12m high, which he added benefit of generating a permanent, objective record. Terrestrial LiDAR proved neither particularly accurate nor cost-effective. Finally, operator-based, reliability problems emerged with all methods, with discrepancies of at least 11%. Overall, digital photography taken and archived, but not analyzed, was the most cost-effective, accurate, and reliable approach.