The Grand Avenue Bridge, a vital thoroughfare in downtown Chicago, presented a complex project spanning 6,132 square feet. The challenge was in balancing the City of Chicago’s preference for a solid bridge deck for noise reduction and improved tire traction, with the critical deck deadload considerations for this movable bridge.

Innovatively, we solved this problem by using a 5-inch, 4-way half-filled concrete galvanized welded diagonal bridge grid deck across two-thirds of the deck area, leaving the remaining third as an open grid deck. This managed the deck deadload design limitations while addressing the city’s preferences.

Another challenge lay in attaching the grid deck to the existing support steel. To address this, continuous bolt-down plates were shop-welded to the bottom of the grid deck panels atop every supporting steel top flange. With the existing deck support steel already having holes, the installer could field drill holes in the bolt-down plates from underneath the bridge, thus eliminating any hole alignment issues. This meant that bolting the deck to the supports could be achieved from underneath the bridge deck.

The successful delivery of this project underlines Frontier Gratings’ commitment to innovative problem-solving, meticulous planning, and timely execution.