Baltimore’s Francis Scott Key Bridge collapsed after being hit by a cargo boat.

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sdifox

No Lifer
Sep 30, 2005
96,129
15,763
126
Just glancing at the site you'd need something about the size of the Verrazano which wile doable certainly would have cost a hell of a lot more than a suitable truss bridge.

truss bridge cannot span 366m
 

IronWing

No Lifer
Jul 20, 2001
69,486
27,757
136
It's an interesting design with the central truss arch with roadway suspended beneath. I suspect the engineers were given direction to build the cheapest possible bridge that would allow ships to pass.

 
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Hans Gruber

Platinum Member
Dec 23, 2006
2,217
1,153
136
umm whut? it's 2,600m long, with the longest span being 366m. what kind of bridge do you envision they could have built in the 70s? Also, the water is about 15m deep near the bridge.

makes more sense to protect bridge supports.
I was trying to decide if you were serious or joking. The Golden Gate Bridge was built in 1937 and has a span between towers of 4,200ft. The total length of the bridge that collapsed is 8600ft and of that 1200ft is the longest span in that tangled mess of steel. There are two sections in that bridge for about 2,400 feet that have a joining span in the middle. The rest of the bridge is like a concrete causeway similar to what they have in Florida.

The longest span between support towers on a suspension bridge is 2023m or 6637ft.

There is more than enough space for a suspension bridge making it impossible for a cargo ship or cruise ship to impact the bridge. A clearance of 225ft above the waterline would be best because they keep building bigger and taller boats.
 
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fskimospy

Elite Member
Mar 10, 2006
84,735
49,350
136
It's an interesting design with the central truss arch with roadway suspended beneath. I suspect the engineers were given direction to build the cheapest possible bridge that would allow ships to pass.

View attachment 95901
Which really is probably a smart ask. We should not be designing bridges to withstand impacts from giant fucking cargo ships.
 
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sdifox

No Lifer
Sep 30, 2005
96,129
15,763
126
I was trying to decide if you were serious or joking. The Golden Gate Bridge was built in 1937 and has a span between towers of 4,200ft. The total length of the bridge that collapsed is 8600ft and of that 1200ft is the longest span in that tangled mess of steel. There are two sections in that bridge for about 2,400 feet that have a joining span in the middle. The rest of the bridge is like a concrete causeway similar to what they have in Florida.

The longest span between support towers on a suspension bridge is 2023m or 6637ft.

There is more than enough space for a suspension bridge making it impossible for a cargo ship or cruise ship to impact the bridge. A clearance of 225ft above the waterline would be best because they keep building bigger and taller boats.


Pretty sure if you ram Golden Gate Bridge towers it will fail too. Water is about 33m deep at the south tower.
 
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skyking

Lifer
Nov 21, 2001
22,215
5,075
146
Pretty sure if you ram golden gate bridge towers it will fail too.
The south pier is constructed with 105,000 cubic yards of concrete and has a massive concrete fender system. It protects the steel bridge structure.
The bridge that collapsed in Baltimore was downright naked. I think some dolpins and fender systems is a great idea and they use them all over to protect pridge structures.
 

K1052

Elite Member
Aug 21, 2003
46,777
34,667
136
Pretty sure if you ram golden gate bridge towers it will fail too.

North tower base is perched on rock right around sea level. You'd be aground well before reaching it.

South tower base is protected by a huge steel reinforced concrete fender 40ft thick.
 

sdifox

No Lifer
Sep 30, 2005
96,129
15,763
126
The south pier is constructed with 105,000 cubic yards of concrete and has a massive concrete fender system. It protects the steel bridge structure.
The bridge that collapsed in Baltimore was downright naked. I think some dolpins and fender systems is a great idea and they use them all over to protect pridge structures.

Not a civil engineer but I imagine 95k tonne doesn't stop on a dime. Apparently it was doing 9 knots, that is a lot of momentum.
 
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Hans Gruber

Platinum Member
Dec 23, 2006
2,217
1,153
136
A tunnel would be the best option. I only pointed out a suspension bridge would be a better option because the support columns could be on land nowhere near a ship on the water.
 

brycejones

Lifer
Oct 18, 2005
26,627
24,871
136
A tunnel would be the best option. I only pointed out a suspension bridge would be a better option because the support columns could be on land nowhere near a ship on the water.
Long tunnels have their own risks. See various tunnel fires caused by car accidents. No solution is going to be completely risk free for going over or under a large body of water.
 

skyking

Lifer
Nov 21, 2001
22,215
5,075
146
Not a civil engineer but I imagine 95k tonne doesn't stop on a dime.
They had plenty of speed on for steerage, for sure. Even with the loss of power I will expect that excess speed will be in the final accident investigation report.
I have witnessed what "I'm coming in hot" does with big ships.
We were working on a hazmat cleanup job, dredging mud from under the docks in the city waterway (now the Sitcum waterway) in Tacoma. It was tide work and we were tied up across the way on SeaLand's dock, with all the dredge pipe pulled over tight out of the way for the show that was about to happen.
Mansons 28" cutter suction dredge "The General" was digging for depth up the Blair waterway in hard sand. They had the discharge pipe running across the mouth of our waterway anchored down with big weights.
The pilot and captain of the ore hauler that was sitting in Commencement Bay was concerned about that pipe so they waited until high tide to get all the clearance possible.
About midnight, one of the two Crowley Marine tugs came to the dock and took the pilot out there.
They got underway and started making a lot of smoke heading our way. I bet they had 6 knots when they entered the 2800' long waterway!
John and I stepped up off the dredge, figuring that they might just swamp us in all the commotion.
The two ocean going tugs, not tractors mind you but straight screw tugs were made up bow and stern and that ship started backing down hard. They had to push hard to counteract the walk but had a heck of a time doing much else.
They came by our rig with about 20' to spare, washing our deck with prop wash, then he angled a bit more to clear the SeaLand D7 ahead of us. You could hear the prop blast coming up out of Sealand's hull like a drum beat.
Here is a D7 in the same spot on the dock.


They blew right past the ore crane on the dock and ran all the way to the end about 1200' beyond their berth, and right up to the Port of Tacoma offices. I don't know if they ran aground or not.
In the middle of all this the lady in the security truck said "you know you are too far" No shizzle captain obvious.
This frazzled voice comes back, just about breaking with emotion and says " we're doing the best we can!"
It took them an hour to get back to where they belonged. We were still tided out and just drank our coffee and watched the show.

A dolphin and fender guard does not have to stop the ship, it can sacrifice itself and deflect it. We have them all over protecting bridge abutments and things. That bridge was just naked. When they upgrade the port for the big containers they need to look at the whole picture.
 
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