I-93 Leonard P. Zakim Bunker Hill Bridge

Project Detail

“The Leonard P. Zakim Bunker Hill Memorial Bridge, part of The Big Dig" Project in Boston, is one of the widest cable-stayed bridges in the world. The Bridge serves as the northern entrance to and exit from Boston. The Bridge is named after civil rights activist Lenny Zakim and the American colonists who fought the British in the Battle of Bunker Hill.”
– Governor Jane Swift at 2002 Bridge dedication.

Project Highlights

The Zakim Bridge is impressive as an entrance to Boston for drivers coming from the North and has become a New England landmark. At night, the lighting effect is nothing short of spectacular.

  • The overall concept for the bridge was designed by Swiss engineer Christian Menn and executed by numerous builders.
  • The attached cables of the tower legs as well as the vertical section, result in two different V-shapes.
  • The two inverted-Y tower design consists of the 295 feet tall south tower and the north tower at 323 feet.
  • The Zakim Bunker Hill Memorial Bridge is among the widest cable-stayed bridges in the world.
  • The Zakim Bridge is noteworthy for being America’s first hybrid cable-stayed bridge. As the structure was built using both the methods for steel and concrete frame construction.
  • The two upside-y-shaped towers are meant to mimic the nearby obelisk-like Bunker Hill Monument.
  • The cables extending from the two towers form massive triangles, emulating the appearance of ships’ sails.

Client: Massachusetts Department of Transportation (MassDOT)

Location: Boston, Massachusetts

Area: 745-foot main span

Finished: 2003

Cost: $105 Million

Remarks: The 10-lane asymmetrical cable-stayed bridge has been recognized as a monumental achievement in American bridge engineering and construction.


A focal point in the Boston skyline and winner of the 2004 OPAL Award from the American Society of Civil Engineers, this unique bridge has twin planes of stay cables in the 745- foot main span and a single plane of stays in the back spans. Recognized as the widest cable-stayed bridge in the world at 183 feet, the bridge carries ten lanes of traffic. The bridge is asymmetrical in both directions and is hybrid steel and concrete design.

the challenges

One major challenge of this project 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.

project goals

The goal of the project was to update the city’s transportation system, making it safer, more efficient, and more environmentally friendly.

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