Posts filed under: Survey

With replacement of the I-75 bridge decks over both the Rouge River and Fort Street in Detroit scheduled for 2017, a design survey was needed to collect data and map the 1967 bridges, approaches and ramps. A massive amount of data was collected on two miles of eight-lane highway, including the 1.5-mile bridge over the Rouge River that boasts the largest concrete deck surface in Michigan. This bridge is supported by 105 piers up to 100 feet high and connects to the 822-foot bridge over Fort Street to create the two-mile span. The right mix of surveying technologies was used to collect and fuse the data into highly-accurate mapping for the Michigan Department of Transportation with minimal disruption to the bridges’ 115,000 daily drivers. The project has been honored by the American Council of Engineering Companies with a National Recognition Award and an Eminent Conceptor Award from the Michigan organization.

A combination of Mobile Terrestrial Lidar (MTL) scanning, Stationary Terrestrial Lidar Survey (STLS) scanning, and conventional surveying technologies was used; the largest application of its kind that has been performed in Michigan. More than 200 million laser scanning points were collected. Numerous challenges were overcome by developing a project approach that addressed heavy traffic, trains, difficult and congested working conditions, and impediments to equipment mobility. In addition, bridge heights required surveyors to use a 135-foot-high boom lift to measure distances to determine bearing dimensions and haunch heights, and perform limited laser scanning.

Control targets and mapping data were repeatedly verified to account for vibration impacts and achieve required accuracies. Data gathered from the various survey methods was edited, merged and delivered as comprehensive and detailed mapping that eliminates the need to return to the field during design. The design survey will be used by design and construction engineers during the reconstruction project and as a source of information for future assessments of bridge deterioration.

Trigonometry is a critical math skill for Wade Trim surveyors who perform a variety of land surveying and mapping tasks. It is also critical for high school students who participate in the National Society of Professional Surveyors Trig-Star competition on the local, state and national levels. For the past 20 years, Wade Trim has sponsored the Trig-Star program in the Village of Goodrich, MI. Jim Kovas, PS, PE, has led this effort, working with John Doerr, mathematics teacher, and students to explain surveying activities and demonstrate equipment. We are proud to congratulate the 2015 State of Michigan Trig-Star Champion, Erika Lustig, a Goodrich High School senior. Erika completed her test with a perfect score in the fastest time across the entire state, earning a scholarship award and the opportunity to compete at the national Trig-Star competition in June. She plans to attend Michigan State University this fall majoring in mathematics and computer science.

High tech surveying and 3D modeling were used to evaluate repair methods for restoring operation of Wayne County’s historic Jefferson Avenue Bridge over the Rouge River in Detroit, MI. Extensive damage to this drawbridge’s north leaf and related mechanical features has kept it closed to vehicle traffic since a collision with a freighter in 2013.

Wade Trim completed a laser scan of the exterior of the bridge, interior machinery pits of the displaced north leaf, and the minorly damaged south leaf. After control and benchmarks were laid out, a Leica P-20 laser scanner was used to obtain more than 30 scan positions from both sides of the river. The scan positions were registered into a single point cloud that allowed our staff to obtain precise measurements and positions of all structural elements. It was determined that the north leaf has to be moved more than seven inches to properly align with the south leaf when the drawbridge is lowered into the horizontal position.

Bridge structures were modeled in 3D to show the amount of warping in the steel girders and beams. The 3D modeling also allowed measurements to be made on the center of the trunnion bearings’ axle, used to raise and lower the bridge spans, to show how much the structure had displaced. The model is being used by the design team to evaluate stresses and displacements caused by the collision and work methods to restore operation.


The north leaf of the bridge was twisted and pushed more than seven inches away from its anchor bolts by the collision.


The laser scan allowed accurate measurements to be taken that will be used to plan structural repairs and movement of the north leaf back into the correct position needed for smooth operation.