Bridge builders got some help from the tides to install the 3-million-pound center lift span for the new Sarah Mildred Long Bridge, which connects Kittery, Maine, and Portsmouth, New Hampshire.
On October 17, the span was floated in on barges across the Piscataqua River. Then on October 18, the rising tide lifted the span above the bearings. It was later positioned into place so the receding tide would lower it onto the bearings. The barge then backed away from the span when the tide was low enough.
The new bridge alignment, with a 56-foot vertical clearance, is designed to allow larger ships access to the nearby port and shipyard. That will reduce bridge openings by 68 percent, according to the Maine Department of Transportation. The bridge’s 300-foot-long lift span is supported by 200-foot-tall precast concrete towers.
The bridge will be lifted and lowered by eight steel cables that pull counterweights.
“If laid end to end, these operating ropes would stretch over a mile, and the 40 counterweight ropes that support the four corners of the new lifts span would extend over 2 miles,” the Maine DOT says.
The Maine DOT is working with the New Hampshire Department of Transportation to build the $160 million bridge. Construction began in 2015, with Cianbro of Maine serving as the prime contractor.
The bridge is scheduled to open in November. Final construction should be completed June 1.
To view web cams on the project, go to maine.gov/mdot/sml/.