BOSTON -- The crowning jewel of Boston's Big Dig project reached a milestone Tuesday, as the last section of decking was fitted on the Leonard P. Zakim Bunker Hill Bridge.

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NewsCenter 5's Jack Harper reports that the bridge, which spans the Charles River, will be finished ahead of schedule in September.

"This has been four years of pure pleasure building this bridge, and now the deck's here," lead field engineer Kirk Elwell said. "September we're all done, so it's been great."

The final piece of the $100 million bridge was fitted into place on what will be the widest cable-staid bridge in the world, with 10 lanes along its 1,500-foot length.

Workers paused for a moment Tuesday to remember Congressman Joe Moakley, who helped secure much of the funding for the Big Dig project.

"If you look at the structure, you see the tower and you get the representation of the Bunker Hill monument, but the cables to me represent the sea ... so to me that represents the past, present and future," chief bridge engineer Tony Ricci said.

Although the bridge will be done soon, the road that leads to it will not be ready for about another year. Engineers said that the bridge can withstand wind gusts up to 420 mph.