Zakim Bridge: Construction & Facts

Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

The Zakim Bridge is a very impressive modern structure. In this lesson, we'll explore the history and design behind this bridge, and see what makes it so unique amongst American bridges.

The Leonard P. Zakim Bunker Hill Memorial Bridge

What's a great way to honor a civil rights activist who spent his life trying to bridge the gaps between people in one of America's great cities? How about naming a bridge after him? Seems appropriate. The Leonard P. Zakim Bunker Hill Memorial Bridge is quickly becoming one of the most iconic landmarks of Boston, notable for exceptional design and functionality. After all, if you're going to name a bridge after someone you really respect, it had better be a great one.

The Zakim Bridge of Boston

Design and Construction

In the late 20th century, Boston started work on an extremely ambitious infrastructural overhaul known as the Big Dig. The goal of the project was to update the city's transportation systems, making it safer, more efficient and more environmentally friendly. Part of this massive undertaking required the replacement of outdated bridges. One such bridge to be selected for demolition was the Charlestown High Bridge, crossing the Charles River at the north entry into Boston.

This meant that a new bridge would be needed. The overall concept for the bridge was designed by Swiss engineer Christian Menn, and executed by numerous designers and builders in the United States. Rather than a simple truss bridge like the one being replaced, the new bridge was meant to be bold, modern, and iconic. The design that the city finally agreed on was a massive cable-stayed bridge, in which the cables are anchored directly to the deck, rather than being strung from tower to tower. This design is not commonly used in the United States, where suspension bridges have long been the design of choice, so it's a unique addition to the city's skyline.

In a cable-stayed bridge, the cables are anchored directly to the deck

The Zakim Bridge is also unique in a few other ways. For one, it's really wide. In fact, with a total of ten lanes, it's among the widest cable-stayed bridges in the world. The two outside lanes are so far removed from the center that they are actually cantilevered, supported in a different way than the other decks. This gives the bridge a uniquely asymmetrical appearance.

Finally, the Zakim Bridge is noteworthy for being America's first hybrid cable-stayed bridge. This means that the structure is built using both the methods for steel and concrete frame construction. In this case, the main span is supported by steel girder and floor beams, while the back spans are instead made of concrete. With these innovative features, the 1,432-foot Zakim Bridge opened to the public in 2003 and has been a staple of the city's transportation infrastructure ever since.


The Zakim Bridge is an undeniably cool structure, but we can't fully appreciate it without understanding all the symbolism it contains. The two upside-y-shaped towers, for example, are meant to mimic the nearby obelisk-like Bunker Hill Monument, which marks the location of one of the first major battles of the American Revolution. While the American revolutionaries lost the battle, they put up an incredible fight. The British only won at heavy cost, bolstering confidence within the American Continental Army and convincing many that they might actually be able to win this war.

The cables themselves are also important. In this case, the cables extending from the two towers form massive triangles, emulating the appearance of ships' sails. This is a reminder of the importance of Boston as a shipbuilding center throughout American history, and specifically a nod to the USS Constitution, a leading ship of the War of 1812 that was built in Boston Harbor.

The sail-like cables, as seen from the river

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