Saturday, November 14, 2020

I-93/US-1 2003 Leonard P. Zakim Bunker Hill Memorial Bridge in Boston, MA

(Bridge Hunter; John A. Weeks III; GeekyGirlEngineer; 3D Satellite)



John Weeks

The Leonard P. Zakim Bunker Hill Memorial Bridge was the widest cable-stayed bridge in world at 183 ft (55.7m) when it opened in 2003 as part of the "Big Dig" project. It serves as the northern entrance and exit to the city of Boston and terminates at the entrance to the Thomas P. "Tip" O'Neill Jr. Tunnel. The two towers are built to represent the Bunker Hill Monument that stands close-by in Charlestown. It provides a total of 8 lanes of north-south traffic plus an additional 2 lanes of an access ramp that is attached via a cantilever connection. [BridgeHunter]
"The Bridge is named after civil rights activist Lenny Zakim and the American colonists who fought the British in the Battle of Bunker Hill." [leonardpzakimbunkerhillbridge]

Study
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.
 
Highway Engineering Discoveries posted
Boston Massachusetts USA
HED posted again

BostonRoads
This 2001 photo shows the northbound I-93 over the old High Bridge. The Leonard P. Zakim-Bunker Hill Memorial Bridge under construction on the left. (Photo by Jim K. Georges.)

The I-93 bridge that it replaced was literally falling apart! "On May 28, 1999, motorists bound for northern New England for the Memorial Day weekend that Friday afternoon experienced tire blowouts. The Massachusetts State Police shut down the bridge, and inspectors discovered that the upper deck of the High Bridge separated from the roadway by eight inches. The cause: three of the four rusted stringer beams supporting the upper deck had failed." [BostonRoads]

Highway Engineering Discoveries posted
Dope as always Boston Massachusetts USA
[It must be rush hour. Most of the traffic is going one way.]

The bridge is a hybird that uses a steel truss for the main span and post-tensioned concrete for the north and south spans. That is why the cables between the towers go to the outside of the deck, but the cables to the sides of the towers go to the center of the deck. [JohnWeeks, BostonRoads, ChristianMenn]

This was supposed to be 101 photos of the bridge by Don Eyles, but I was not able to access any of them.

Street View

Street View

Street View

Street View
This is a double shock.
1) The Street View is out of the car and using a portable camera. I've never seen that before.
2) The public is allowed to walk on the gates of the locks.

Street View

Street View

The Big Dig is one of the three candidates in my mind for the biggest boondoggle (cost overrun) in the U.S. (The other two are the tunnel in Seattle and Olmsted Dam. I just discovered that I have added the $64b California bullet train to that list. So it is now a race among four projects as to which was worse.)



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