Dimetix laser distance sensors monitor bridge lift

Ten DLS-C15 laser distance sensors from Dimetix USA were lifted aboard a 2,650 ton steel bridge truss section over the Mississippi River in New Orleans, Louisiana on June 19, 2010. DIMETIX USA made history when Tom Weinmann of Applied GeoMechanics (Buffalo Grove, IL; www.geomechanics.com) worked with MTI in New Orleans to monitor the lifting of a truss section on the Huey P. Long Bridge. The Dimetix DLS-C15 laser distance sensors were used in conjunction with specially fabricated targets and software developed by Applied GeoMechanics to monitor beam deflection during the day long lift.

The project involved barging in and lifting pre-assembled spans to reduce stress on the bridge and minimize interruption of traffic. At first, Applied GeoMechanics nor the contractor (MTI), believed that a series of laser distance sensors and geometric target plates could detect deflection over such long beam spans outdoors and on the water. Steven Lubeck of DIMETIX USA convinced engineers otherwise by staging a proof of concept test on land. Further testing on-site proved the method to be valid.
The longest beam span on this truss section was approximately 30 meters, but longer spans should be feasible based on the 150 meter measurement range of the DLS-C30 laser distance sensor.
The DLS-C30 laser distance sensor is shown here in a paired configuration midspan on the truss section.
Photos are courtesy of Applied GeoMechanics (Buffalo Grove, IL) and ENR.com.