Bridge Inspection & Change Detection
Non-Contact Inspection of Aging Infrastructure
With more than 10% of bridges rated as "structurally deficient" there is an urgent need for an easier and cost effective way to perform bridge inspections. One of the challenges in bridge inspections is the underwater section, where most of the problems and greatest uncertainty exist. According to a report from the Federal Highway Administration: “The most common cause of bridge failure is from floods scouring bed material from around bridge foundations. Scour is the engineering term for water-induced erosion of the soil surrounding bridge foundations, piers, and abutments.
ASTRALiTe has performed surveys that produced highly accurate LiDAR point clouds that capture the river cross-section. This can be compared to historical data to determine changes over time. It also establishes a baseline for any future comparisons.
Scour = 1.5ft or ~1/2 meter
Scour = 2.5ft or ~1 meter
Debris Build Up
The figure above shows a bridge inspection point cloud overlayed onto a photo of a commuter rail bridge (blue-green-beige represent bathymetric points; red-yellow topographic points). Scour-induced collapse of the foundation underpinnings of a bridge is a common cause of bridge failure. The LiDAR data collected by our modified EDGE lidar system clearly shows scour around Pier #2 and Pier #4. This is somewhat surprising as this bridge is relatively new (the commuter line just opened September 2020).
The LiDAR also detects buildup of debris, tree branches, etc. around the Piers. This is evident on Piers #1 in the figure above where a large brush pile wraps the upstream side of the Pier. This lidar data can help estimate the volume of material needing to be removed after large run-off or flood events in order to avoid erosion of stream banks and scour at abutments, or piers. Removal of debris reduces risk of structural damage, and avoids costly future repairs.