The Leonard P. Zakim Bunker Hill Memorial Bridge as seen from Boston’s Inner Harbor looking west towards the west of the Charles river. Also visible are the Charlestown Bridge and the New Charles River Dam.
The Leonard P. Zakim Bunker Hill Memorial Bridge was designed by a team led by Christian Menn. Opened in 2003, the bridge was built as part of the Big Dig (Central Artery/Tunnel Project) and carries I-93 and US-1 across the Charles River. At the time of its opening, the bridge was the widest cable-stayed bridge in the world with eight main lanes between the harp-style cables connecting the Tip O’Neill Tunnel and the two additional cantilevered lanes connecting the Sumner Tunnel to the elevated highway structure in Charlestown. The Zakim Bridge replaced the Charlestown High Bridge, a double-decked truss bridge demolished in 2004.
The “New” Charles River Dam, also known as the Gridley Dam, is located just downstream of the Zakim Bridge and was built in 1978. Built to keep sea water out of the Charles river basin, a function the “Old” Charles River Dam Bridge of 1912 further up-stream is no longer able complete properly, the structure contains three locks, a fish ladder, a pump-hydro station, and the Massachusetts State Police Marine Section Barracks.
Just downstream of the New Charles River Dam is the Charlestown bridge, which is the easternmost crossing on the Charles River. Built in 1900 and designed by William Jackson the bridge has plate girder approaches and a truss swing span, carrying 6 lanes of North Washington Street from the North End to Charlestown The bridge is scheduled to be replaced over 4 years starting in 2017 .