Leonard P. Zakim Bunker Hill Memorial Bridge

Zakim Bunker Hill Bridge
Zakim Bunker Hill Bridge
	The bridge, seen in 2011
Coordinates	42°22′08″N 71°03′48″W / 42.36889°N 71.06333°W
Carries	10 lanes of I-93 / US 1
Crosses	Charles River, MBTA Orange Line
Locale	Boston, Massachusetts; (North End–Charlestown)
Official name	Leonard P. Zakim Bunker Hill Memorial Bridge
Owner	Commonwealth of Massachusetts
Maintained by	Massachusetts Department of Transportation
Characteristics
Design	Cable-stayed bridge
Material	Steel, prestressed concrete
Total length	1,432 ft (436 m)
Width	183 ft (56 m)
Height	270 ft (82 m)
Longest span	745 ft (227 m)
Clearance below	40 ft (12 m)
History
Construction cost	$105 million
Opened	March 30, 2003 (northbound); December 20, 2003 (southbound)
Location

The Leonard P. Zakim (/ˈzeɪkəm/) Bunker Hill Memorial Bridge (also known as "The Zakim") is a cable-stayed bridge completed in 2003 across the Charles River in Boston, Massachusetts. It is a replacement for the Charlestown High Bridge, an older truss bridge constructed in the 1950s.

The bridge and connecting tunnel were built as part of the Big Dig, the largest highway construction project in the United States. The bridge's unique styling quickly became an icon for Boston, often featured in the backdrop of national news channels, to establish location, and included on tourist souvenirs. The bridge is commonly referred to as the "Zakim Bridge" or "Bunker Hill Bridge" by residents of nearby Charlestown.

The Leverett Circle Connector Bridge was constructed in conjunction with the Zakim Bridge, allowing some traffic to bypass it.

Design

The bridge concept was designed by Swiss civil engineer Christian Menn in collaboration with bridge designer Miguel Rosales and its design was engineered by American civil engineer Ruchu Hsu with Parsons Brinckerhoff.^[2]^[3]^[4] Wallace Floyd Associates, sub-consultants to Bechtel/Parsons Brinckerhoff, was the lead architect/urban designer and facilitated community participation during the design process.^[5]^[6]

The bridge is a cable-stayed bridge in a harp configuration with cradles carrying each strand through their pylon. The main portion of the Zakim Bridge carries four lanes each way (northbound and southbound) of Interstate 93 (concurrent with U.S. Route 1) between the Thomas P. "Tip" O'Neill Jr. Tunnel and the elevated highway to the north. Two additional lanes are cantilevered outside the cables, which carry northbound traffic from the Sumner Tunnel and North End on-ramp. These lanes merge with the main highway north of the bridge. I-93 heads toward New Hampshire as the "Northern Expressway", and US 1 splits from the Interstate and travels northeast toward Massachusetts' North Shore communities, crossing the Mystic River via the Tobin Bridge.

The 1975-built MBTA Orange Line's Haymarket North Extension tunnel lies beneath the bridge.

Dedication

The bridge's full name commemorates Boston area leader and civil rights activist Leonard P. Zakim, who championed "building bridges between peoples",^[7] and the Battle of Bunker Hill.

The bridge was dedicated on October 4, 2002, in a ceremony held on the new span. The dedication speakers included members of Zakim's family, government officials, and a performance of the song "Thunder Road" by Bruce Springsteen.^[8]

Introducing the song, Springsteen said about Zakim, "... I knew him a little bit during the last year of his life, he was one of those people whose, intensity, inner spirit you could feel even when he was very ill, ... we honor his memory obviously not with this beautiful bridge, very lovely, but by continuing on in his fight for social justice."^[9]

Landscape design and public art

Under Zakim Bridge, Five Beacons for the Lost Half Mile, blue phase

Five Beacons for the Lost Half Mile, orange phase, view to West

Placement of footings for the Zakim Bridge required environmental permits to relocate areas of open water surface, changing the contour of the Charles River shoreline. The process of landscape design and environmental mitigation under the bridge deck and around the bridge supports allowed for the creation of a new and accessible public landscape designed by Carol R. Johnson Associates. This under bridge landscape contains a series of perforated stainless steel lighting-based public artworks, entitled, Five Beacons for the Lost Half Mile.

Pedestrians and cyclists are able to travel from Charlestown toward Cambridge over the adjacent North Bank Bridge to North Point Park.^[10] This bridge is a link in the Charles River Bike Path and a segment of the Mass Central Rail Trail and the East Coast Greenway.