Reliability of crack detection methods 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 preconstruction, 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 two brick and two concrete buildings (8.2-14.3 m high) in Dublin, Ireland. Results showed that nonmanual methods tended to overpredict 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 12 m high, which has the added benefit of generating a permanent objective record. The terrestrial LiDAR proved neither particularly accurate nor cost-effective at the selected point density of less than 2mm×2mm. 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.