Fascinating infrastructure story in the NY Times today: The Port Authority has started on a $1 billion project to clean the George Washington Bridge's" four main cables and also replace, for the first time, all of the 592 vertical suspender ropes that hold up the roadway."

The bridge turned 80 years old on October 25, and apparently similar bridges have replaced their cables after 70 years. The Times reports:

Although the agency has never replaced the bridge’s suspender ropes, which weigh 1,500 to 10,000 pounds each, depending on their length, the procedure is expected to be similar to the work done at the Golden Gate Bridge. For that project, a rolling platform, also known as a traveler, was placed atop the main cables, and then workers replaced the ropes, using temporary suspenders, jacking frames and jacks.

The project, which agency officials estimated would create 3,600 jobs, is daunting in its magnitude: the suspender ropes, if placed end to end, would be 32 miles long. If the 283 wires in each suspender rope were laid end to end, they would be 9,100 miles long — more than one-third of the circumference of the Earth around the equator.

The Port Authority's Andrea Giorgi Bocker, the bridge's resident engineer, said, "This is a structural engineer’s dream."

Its beacon celebrated its 75th birthday last year.