Boston Gains An Asymmetrical Icon

The Bunker Hill Bridge in Boston USA is the widest cable-stayed bridge in the world, and the first to employ a steel box girder for its main span and post-tensioned concrete in the back spans.

Many cities are defined by structures - London by Tower Bridge, Paris by the Eiffel Tower, New York by the Statue of Liberty.

Now it appears that the image of Boston will be spread across the world by means of the asymmetrical bridge that carries Interstate 93 across the Charles River.

That would be a fitting icon for a city famous for the Battle of Bunker Hill, the nearby monument for which is reflected in the design of the structure's inverted Y-shaped towers.

From these radiate the stays which give the bridge its distinctive appearance.

To give it its full title, it is the Leonard P.

Zakim Bunker Hill Bridge, unique for more than one reason: it is the widest cable-stayed bridge in the world, the first to employ a steel box girder for its main span and post-tensioned concrete in the back spans.

The word asymmetrical here has a special significance: the bridge has neither longitudinal nor transverse symmetry.

This widely admired structure was added to the Central Artery Project as a major element of the environmental mitigation program which required $3 billion funding, 20 per cent of the project's overall cost.

CIOB International continues its reports on Boston's $15 billion Big Dig with a series of interviews with the project's leading executives: Matt Wiley, Program Manager; Keith Sibley, Construction Manager: Bill Edwards, Budget Manager and John Saroufim, Construction Controls Manager.

Each has his own story to tell from the standpoint of the Bechtel/Parsons Brinckerhoff project management joint venture.

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