Leonard P. Zakim Bunker Hill Memorial Bridge

The Leonard P. Zakim Bunker Hill Memorial Bridge is a cable-stayed bridge that carries eight lanes of the Interstate 93 and U.S. Route 1 concurrency, plus a two lane access ramp, across the Charles River in Boston, Massachusetts. The bridge was built as part of the Big Dig, the largest overall highway construction project in the United States. The entrance to the Thomas P. "Tip" O'Neill Jr. Tunnel, another major component of the Big Dig, is at the bridge's southern end, while north of the bridge I-93 heads toward New Hampshire and US 1 splits from the Interstate and travels northeast toward Massachusetts' north shore, crossing the Mystic River via the Tobin Bridge. The bridge replaced the Charlestown High Bridge when it opened, and is the world's widest cable-stayed bridge. The bridge is now a major landmark and major piece of the Boston skyline. It has been featured in several films recently including the 2005 version of War of the Worlds and Martin Scorsese's The Departed. It can also be briefly seen in the opening credits of the television show, Boston Legal and often serves as a backdrop for interviews on cable news channels.

Zakim Bunker Hill Bridge
Zakim Bunker Hill Bridge
Coordinates	42°22′09″N 71°03′51″W / 42.36917°N 71.06417°W
Carries	Interstate 93 and U.S. Route 1
Crosses	Charles River
Locale	Boston, Massachusetts
Official name	Leonard P Zakim-Bunker Hill Memorial Bridge
Maintained by	Massachusetts Turnpike Authority
Characteristics
Design	Hybrid Steel and Concrete Cable-stayed bridge[1]
Total length	1432 ft (436.5m)
Width	183 ft (55.7m)
Height	270 ft (98.4m)[2]
Longest span	745 ft (227.1m)
Clearance below	40 ft (12.2m)[3]
History
Opened	March 30, 2003 (NB) December 20, 2003 (SB)[3]
Location

In a cable-stayed bridge, instead of hanging the roadbed from cables slung over towers, the cables run directly between the roadbed and the towers. Although cable-stayed bridges have been common in Europe since World War II, they are relatively new to North America.

The bridge concept was developed by Swiss civil engineer Christian Menn and its design was engineered by American civil engineer Ruchu Hsu with Bechtel Parson Brinckerhoff. Boston-based architect Miguel Rosales was the lead architect/urban designer and facilitated community participation during the design process. Neither Hsu nor Rosales served as the designer of record for the project. The engineer of record is HNTB/FIGG. The lead designer from HNTB was Theodore Zoli; and W. Denney Pate from FIGG. The bridge follows a new design in which two outer lanes are cantilevered outside the towers while another eight lanes run through the towers. It has a striking, graceful appearance that is meant to echo the tower of the Bunker Hill Monument, which is within view of the bridge, and the white cables evoke imagery of the sails of the USS Constitution.

According to the Massachusetts Turnpike Authority's web site, the bridge has an overall length of 436.5 m, a main span of 227.1 m, side spans of 81.4 m (downtown side) and 128.0 m (Charlestown side), and towers that are 82.3 m tall.^[1] The bridge was designed to withstand high winds. While the highest wind gusts recorded in Boston were 110 MPH (175 km/h), the bridge can withstand up to 400 MPH (640 km/h) winds ^[4].

The bridge's full name commemorates both Boston civic leader Leonard P. Zakim, who championed "building bridges between peoples", and the Battle of Bunker Hill. The bridge is commonly referred to as the "Zakim Bridge" by many local Boston newspapers, radio and television media, but many residents of the community of Charlestown and other Bostonians refer to it by its full name, "The Zakim-Bunker Hill Bridge".

• Although the bridge was completed in 2002, it was not opened to traffic until the northbound Central Artery tunnel opened in early 2003. The southbound lanes were opened in December 2003, with the opening of the southbound tunnel, and the cantilevered northbound lanes (a two-lane entrance ramp) opened in April 2005, when the old bridge was sufficiently demolished to allow for their completion.
• The Zakim Bunker Hill cable-stayed bridge has been widely seen as an improvement; it acts as a complete replacement for the previous three-lane, dual height steel bridge, the Charlestown High Bridge. The different heights of the lanes of the I-93 elevated highway in Charlestown are the only remaining hints to the layout of the old bridge.
• In March of 2005, problems arose when it became apparent that ice falling off the cables during the course of winter could land on the roadway below in large enough chunks to possibly endanger motorists, or even break windshields.^[5]
• A local joke nicknames the Zakim Bunker Hill Bridge as the "Bill Buckner Bridge" because the two spires look like legs straddling the highway and the cars "go right through them," alluding to Buckner's famous error during Game 6 of the 1986 World Series.^[6]
• As late as 2007, the Google Maps Satellite Imagery of the area shows an interesting juxtaposition: the two lower quadrants are older data, showing the old dual-height bridge with cars on it. The top left shows the old bridge with no cars; cars are going both directions on the Zakim Bridge. The top right is the newest: the old bridge has disappeared!

• Detail of the cabling and tower on the bridge

• Traveling south on the Zakim-Bunker Hill Bridge

• The bridge during its construction

• The bridge with Boston in the background

• List of crossings of the Charles River

• The Leonard P. Zakim Bunker Hill Bridge web site
• Fact sheet on the Leonard P. Zakim Bunker Hill Bridge
• Leonard P. Zakim Bunker Hill Bridge at Structurae