Lafayette Bridge Mobile LiDAR and Multibeam Survey

Multibeam sonar technology was used to perform a hydraulic survey to support hydraulic analysis for the Lafayette Bascule Bridge over the East Channel of the Saginaw River in Bay City, MI. The purpose of the hydraulic survey was to obtain geometric data on the stream channel upstream and downstream of the bridge and determine the bottom topography and elevations immediately surrounding the bridge.

Utilizing multibeam sonar technology and our mobile LiDAR system, Spicer Group completed LiDAR and sonar acquisition using the same vessel. The dense 3D data provided high-resolution mapping data of the channel bottom, including the vertical surface of the bridge pier structures. The high-resolution data provides engineers a highly detailed image of the severity of scour around each bascule pier. In addition, since scanning covered shoreline to shoreline, our team extracted the required hydraulic cross sections from the data to support development of the HEC-RAS model.

The mobile LiDAR data collected from the marine vessel was combined with the LiDAR collected from a truck on top of the bridge, providing a rich 3D point cloud of the entire bridge structure from the waterline up.  Detailed 3D mapping was then completed using the LiDAR data.