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What exactly is the qualification for a twin suspension bridge?

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SteveG1988:
I mean when the new tacoma narrows bridge stole it from the delaware memorial bridge, i was somewhat upset as the design of the new span is radicaly different, not minorly different like the delaware memorial bridge (the 1968 span has wider lanes, and a different sidewalk, and a few other differences) Does it just have to have the same length main span? or are there more requirements?

*edit*

I wrote this at quite early in the AM, my brain still had the early morning fuzzyness that waking up brings about. Sorry.

But the gist of it is....what exactly are the requirements of a twin span, like if someone builds a longer twin span than the tacoma narrows, what is required, other than it is a suspension bridge, for it to become the worlds longest?

NE2:
Huh?

Duke87:
I would refer to two bridges carrying opposite directions of a highway as twin bridges even if they were completely different.

Alps:
I guess they look at it as two parallel suspension bridges carrying the same highway. If US 9 in Newburgh, NY had bypassed the Port Ewen Suspension Bridge on a new suspension bridge instead of a standard girder design, I wouldn't call them twin bridges because they're crossed by two separate roads, despite being very close to each other. When the new RI 138 bridge was built next to the old one outside Newport, I wouldn't have called them twin bridges even though they were within feet of each other. Has to be the same road, opposite directions (or like US 17 in Charleston once upon a time, reversible lanes allowed).

mapman1071:
Would The West Span Of the San Fransisco - Oakland Bay Bridge Qualify as a twin suspension bridge?
It is 2 Suspension Spans with a anchorage in the center of the "West Bay" Crossing.

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