The Grosse Ile Parkway Bridge crosses the Trenton Channel of the Detroit River in Michigan, connecting Grosse Ile Township to the mainland in Riverview. When high-velocity flows and large depths presented challenges to underwater work needed to repair six of its piers, contractor J.F. Brennan Co., Inc. (Brennan) looked to Barr. We provided hydraulic modeling and a flow evaluation to support the design of temporary flow deflectors around the piers that would help keep underwater workers safe.
Using a two-dimensional Adaptive Hydraulics (AdH) model, we evaluated flow velocities, recirculation patterns, and hydraulic forces around proposed temporary flow deflector structures. Modeling scenarios included various flow rates and deflector configurations to determine optimal placement for minimizing flow impacts during construction. The model was calibrated using site-specific bathymetric surveys and velocity measurements collected during two field campaigns.
Flow deflectors were proposed at all six piers to provide calmer work zones for divers and reduce hydraulic loads on the work area. Barr simulated high-flow conditions (up to 280,000 cfs in the Detroit River, 86,000 cfs in the Trenton Channel) to estimate forces on the deflectors, with results informing anchorage design and construction sequencing. The analysis also quantified potential impacts on adjacent piers and offered strategies to mitigate recirculation zones where velocities exceeded target thresholds.
Barr’s recommendations supported safer and more efficient underwater construction by ensuring the deflector system would perform under anticipated hydraulic conditions while minimizing risk to adjacent infrastructure.
