Maine Department of Transportation—Grist Mill Bridge Replacement Project

The Grist Mill Bridge carries traffic into and out of Bangor – the third largest city in the state of Maine. It had been rehabilitated three times since 1930, each time adding a new surface layer. The challenge with a replacement was the large amount of clean-up required to remove the old ridge and prepare for a longer structure—which would allow for the migration of protected fish and factoring in rising water levels.

Utilizing the next generation of girder bridges—which would extend a bridge’s lifecycle—Maine DOT landed on a girder easier to fabricate, ship, install, and maintain over time. Because the composite girders are so lightweight, the contractor could pre-assemble modules consisting of two girders with all utilities and attachments that could be lifted into place in one pick using smaller equipment. Pedestrian accommodations were also added. This $9 million project resulted in a safer, more resilient bridge is now in place that will require less maintenance moving into the future.