LEONARD P. ZAKIM/BUNKER HILL BRIDGE

Boston, Massachusetts

As the signature of Boston’s Big Dig project, the Leonard P. Zakim/Bunker Hill Bridge (Zakim Bridge) was the world’s widest asymmetrical cable-stayed bridge at the time of construction and the first asymmetrical cable-stayed bridge in the nation. The bridge, which spans from Boston’s North End to Charlestown, Massachussets, consists of ten lanes, and merges I-93 and U.S. Route 1 traffic across the Charles River, into and out of the Thomas P. O’Neill Jr. Tunnel.

The bridge design comprises the hybrid composition of steel in the 745-foot main span and concrete in the bridge back spans, supported by the two, 270-foot inverted Y- shaped towers. The installation presented unique challenges throughout the construction process. One major challenge was having to build the bridge within a busy transportation corridor, consisting of the existing I -93 highway and the Massachusetts Bay Transportation Authority’s Commuter Rail, subway and bus systems, all of which had to operate continuously and seamlessly during construction.

Mass. Electric was responsible for the bridge’s aesthetic lighting, lighting protection, navigation guides and interim power for construction. The work included the installation of over 100,000 feet of conduit and more than 200,000 feet of wire. Over 100 metal halide floodlights, of up to 1000 watts each, wash the structure with blue and white light.