Evaluation of Bridge Approach Slab and Dynamic Load Allowance Using Sub-mm 3D Laser Imaging Technology

Abstract Current evaluation of bumps at bridge approaches is limited in scope and performance, and varies in practice at different state DOTs. This study intends to propose a general criterion specifically for bridge approach bump classification and develop a formula for dynamic load allowance (IM) estimation for bridges in Oklahoma. A total of 98 bridges in Oklahoma were studied using recently developed sub-mm 3D laser imaging technology that simultaneously collected inertial profiles, sub-mm 2D/3D images, and right-of-way images at highway speeds for roughness and distress analysis. A three-level criterion that evaluates maximum roughness within an approach or departure slab is established to classify approach bumps into Good, Fair, and Poor conditions. The threshold defined in the criterion considers both the field crew’s sensation during data collection and the surface distresses that cause or are associated with different levels of International Roughness Index magnitudes. The development of the formula for bridge IM estimation is based on the established criteria while incorporating the influences of bumps from approach slab and bridge deck. The results of evaluating approach bump and IM of 98 bridges demonstrate the ability of using sub-mm 3D laser imaging technology to evaluate bridge approach bumps and bridge IM in an efficient and effective manner.