Barters Island
Bridge Rehabilitation

Boothbay, ME

Pounds Balanced On
A Single Bearing

Modernization Meets Historic Charm and Reconnects Island Community

The Barters Island Bridge provides the only access to Barters Island with population 1,500. The existing steel pony truss swing span, built in 1931, was manually operated and the last of its kind in Maine. Folks from all around the country would sit on the deck of the Trevett Country Store to watch it open to allow the passage of boats on the Back River. Unfortunately, it needed to be load posted to 20 tons due to its poor condition with heavy deterioration exacerbated by the open grid deck. The existing approach spans were replaced in 1983 and still in satisfactory condition but were 7-feet wider than the existing swing span.

The goal of the project was to limit the amount of in-water work, reuse the approach spans, and provide a new fully automated swing bridge with a solid surface deck. To maintain the existing navigational channel width while accommodating the increase in swingpan width to match the approach spans, the new pivot pier was offset, resulting in a bob-tail configuration, and requiring counterweight to balance the unequal spans. When the bridge swings open, the 600,000-pound bridge is balanced on a single point.

The new steel truss was floated into place taking advantage of the 10-foot tides to facilitate setting the truss onto the new pivot pier. The steel members are both metalized and painted with a 3-coat system to protect from corrosion. An exodermic deck with lightweight concrete sped up construction while also providing a solid surface deck. Extensive coordination was required during design with MaineDOT Bridge Maintenance to determine appropriate design features for the new control house, fender system, and maintenance access platforms. The final product is a durable fully automated swing span pony truss that will serve these island communities for decades to come.