The Zakim Bunker Hill Bridge in Boston, Massachusetts is considered to be one of the ten most important bridges in the world. It spans a length of 436 meters, has a width of 56 meters – long enough to hold ten lanes, and has a height of 82 meters. It was completed in December 20, 2003 and became the widest cable-stayed bridge in the world. Moreover, cable-stayed bridges are a rare architectural occurrence in North America and a product of the “Big Dig,” America`s largest highway construction project.
The Zakim Bunker Hill Bridge is one of the best examples of a cable-stayed bridge. In a cable-stayed bridge, the cables run directly between the roadbeds on the towers supporting the bridge. This is in contrast to suspension bridge where the roadbed is connected to the towers indirectly by cables slung between the towers, as in the case of the Golden Gate Bridge in San Francisco. Cable-stayed bridges have been common throughout Europe since the second half of the 20th century. In fact, the very first design of a cable-stayed bridge was published in a book entitled Machinae Novae in 1595. It was the work of the Venetian mathematician and engineer, Fauso Veranzio. The Zakim Bunker Hill Bridge is one of the very few cable-stayed bridges in North America, which were introduced to the continent only during the late 19th century. The stayed-bridge design is considered to be a simpler (less costly) design with much greater stiffness than a suspension bridge.
The Zakim Bunker Hill Bridge was named after two famous names in Boston. Since the bridge location was close to the famous Boston landmark of Bunker Hill, most local residents of Charlestown insisted that the bridge be called Bunker Hill Bridge. Many civic and religious leaders, on the other hand, insisted on calling the bridge Leonard Zakim Bridge. This was the name of a civic leader in Boston known for building bridges between people of different faiths and ethnicity, especially between the Roman Catholic Church and African American communities with the Jewish community of Boston that he represented. As a comprise solution, city officials decided to call the bridge the Zakim Bunker Hill Bridge.
The construction of the bridge fell under the Big Dig project in Boston. The Big Dig project is considered to be the largest highway construction project in United States history. It encompasses several bridges, roads, and tunnels that now compose one of the main roadway arteries of the city. The Zakim Bunker Hill Bridge is arguably the masterpiece of the whole project, from an esthetic and engineering achievement point of view. The concept of what became known as the Big Dig project was conceived in the 1970s. It took several years to implement and several construction companies were hired to complete the project. In the end, the project was completed in 2007, several times over budget and more than a couple of decades behind schedule (it was scheduled to be completed in 1982). The Zakim Bunker Hill Bridge was inaugurated in December 20, 2003. Prior to its opening, its strength was demonstrated by running 14 elephants across the bridge, demonstrating that it can support 112,000 pounds! The tradition of using elephants to test bridges in the United States dates back from the late 19th century (the Brooklyn Bridge was tested in this fashion in 1884!).
Today, the roads constructed by the Big Dig project, including the Zakim Bunker Hill Bridge, have alleviated the downtown congestion of the city of Boston. It is estimated that the bridge is used by hundreds of millions of motorists annually.