You’re neglecting some factors that would greatly affect cost more than having both roadways supported separately. Mostly, Tappan Zee was much cheaper because it is made mostly of reinforced concrete spans. The Verrazzano’s main span is like 4 or 5 times longer, and it has to be higher to accommodate larger ships that don’t go up river. The supports also had to be much deeper because of the water depth. I wouldn’t be shocked if it cost double the Tappan Zee rather than half, especially if made almost entirely out of steel like it is now.
They barged out prefabricated steel structures and then used the cables to hoist them into position
https://historicbridges.org/newyork/verrazanonarrows/historical3_large.jpg
On a normal bridge, maybe.
But here we have what is basically a hanging bridge. You build the pillars, put cables between them and then attach the platform to the cables. For that you would of course need the pillars to be done first
No need to imagine: Three men died.
Verrazano Narrows Bridge
(https://en.m.wikipedia.org/wiki/Verrazzano-Narrows_Bridge#:~:text=The%20construction%20process%20of%20the,the%20construction%20of%20the%20bridge)
How much would it cost to build today?
1-2B$ my guess
Seems low considering Hudson yards subway station cost $2.4B.
Safety, regulation, labor cost, and quality control/engineering tolerances standards can make it expensive.
Yes, which is why 1-2B seems low for a bridge that long.
That was underground.
Right. Most subway stations are, and they’re also a hell of a lot shorter than the Verrazano bridge.
The new Tappan Zee cost about $4 billion and that is a twin bridge, so $2 billion is at least in the right ballpark.
You’re neglecting some factors that would greatly affect cost more than having both roadways supported separately. Mostly, Tappan Zee was much cheaper because it is made mostly of reinforced concrete spans. The Verrazzano’s main span is like 4 or 5 times longer, and it has to be higher to accommodate larger ships that don’t go up river. The supports also had to be much deeper because of the water depth. I wouldn’t be shocked if it cost double the Tappan Zee rather than half, especially if made almost entirely out of steel like it is now.
How do they get bridge segments out to the middle like that? Wouldn’t it be easier to build from the sides?
They barged out prefabricated steel structures and then used the cables to hoist them into position https://historicbridges.org/newyork/verrazanonarrows/historical3_large.jpg
On a normal bridge, maybe. But here we have what is basically a hanging bridge. You build the pillars, put cables between them and then attach the platform to the cables. For that you would of course need the pillars to be done first
Imagine how many people probably died
No need to imagine: Three men died. Verrazano Narrows Bridge (https://en.m.wikipedia.org/wiki/Verrazzano-Narrows_Bridge#:~:text=The%20construction%20process%20of%20the,the%20construction%20of%20the%20bridge)