North Washington St Bridge

BeyondRevenue

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I personally don't believe that anyone had aesthetic goals for the design because it looks like a highway overpass.

It really should not have been unexpected by neither the engineer nor the state. Full penetration welding of thick plates meeting AWS D1.5 requirements is so difficult and costly that it should have never even been an option. If these loads cracked from differential heating/cooling, I can't imagine how badly they would have cracked over time due to fatigue.

This could absolutely be done in a week using accelerated bridge construction processes, especially for such a basic structure. The piers would obviously take much longer to build, but ABC projects even here in Massachusetts have been built in a weekend.
As designed, this is not an overpass common in this country by any means:
 

ceo

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I personally don't believe that anyone had aesthetic goals for the design because it looks like a highway overpass.

It really should not have been unexpected by neither the engineer nor the state. Full penetration welding of thick plates meeting AWS D1.5 requirements is so difficult and costly that it should have never even been an option. If these loads cracked from differential heating/cooling, I can't imagine how badly they would have cracked over time due to fatigue.

This could absolutely be done in a week using accelerated bridge construction processes, especially for such a basic structure. The piers would obviously take much longer to build, but ABC projects even here in Massachusetts have been built in a weekend.
Sure, replacing the superstructure of an overpass on the existing abutments can be done in a weekend, but it is overall more expensive and time-consuming than conventional construction; the advantage is that most of the construction happens off-line. Since the NWSB project involved building new piers, ABC would have offered no advantage, even with more conventional piers that didn't require these thick diaphragms to be welded between the girders. Also, the bridge is 1000 feet long, quite a few times longer than your average overpass.
 

Charlie_mta

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I personally don't believe that anyone had aesthetic goals for the design because it looks like a highway overpass.
The original (old) truss bridge had a gritty industrial look to it that fit the history of the neighborhood. I wish the new one had had more of that old industrial look, instead of this design which looks like Miami Beach.
 

king_vibe

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Sure, replacing the superstructure of an overpass on the existing abutments can be done in a weekend, but it is overall more expensive and time-consuming than conventional construction; the advantage is that most of the construction happens off-line. Since the NWSB project involved building new piers, ABC would have offered no advantage, even with more conventional piers that didn't require these thick diaphragms to be welded between the girders. Also, the bridge is 1000 feet long, quite a few times longer than your average overpass.
The time spent constructing off-site is time saved not constructing in the field. That's where you save time.

Also, the bridge is not 1000 feet long. It's several spans of 200 feet long. If that's too long for rapid construction (it isn't), it could have been broken into more spans. Or replicate the original pier orientation (85' on center) and install a network arch truss bridge over the main span (250'). At least then you'd have something nice to show for it.
 

bigpicture7

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There are roughly 100,000 tub girder bridges in the US that look exactly like this.
king_vibe, no one is denying this could have been executed more simply or that the designers could have made different/easier choices here. However, it is not true to say that this is a conventional design on the order of 100,000x

Image credit @BeeLine :
cb_piers.png


The piers here are in fact independent sets of separate piers. A more conventional approach would have been to have a structurally unified pier (laterally) underlying the girder attachment.

See Post #376 for more elaboration: http://archboston.com/community/threads/north-washington-st-bridge.4504/post-414243

I personally don't believe that anyone had aesthetic goals for the design because it looks like a highway overpass.
Meanwhile, the bridge designers on this project literally brand themselves as "Bridges as Structural Art", so, whether you sense it or not, I am pretty sure those involved in this project view it as at least in part aesthetically driven. This is discussed in the above firm's project page for this bridge.
Within the fact sheet in above: "The design of the elegant piers and overall architecture is inspired by the adjacent Zakim bridge..."

My guess is that these independent V piers are meant to look like upside-down Zakim bridges
 
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king_vibe

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king_vibe, no one is denying this could have been executed more simply or that the designers could have made different/easier choices here. However, it is not true to say that this is a conventional design on the order of 100,000x

Image credit @BeeLine :
View attachment 30012

The piers here are in fact independent sets of separate piers. A more conventional approach would have been to have a structurally unified pier (laterally) underlying the girder attachment.

See Post #376 for more elaboration: http://archboston.com/community/threads/north-washington-st-bridge.4504/post-414243



Meanwhile, the bridge designers on this project literally brand themselves as "Bridges as Structural Art", so, whether you sense it or not, I am pretty sure those involved in this project view it as at least in part aesthetically driven. This is discussed in the above firm's project page for this bridge.
Within the fact sheet in above: "The design of the elegant piers and overall architecture is inspired by the adjacent Zakim bridge..."

And my guess is that these independent V piers are meant to look like upside-down Zakim bridges
They can brand themselves however they want, but it doesn’t change what’s right before your eyes.

Ans my guess is that the V piers are meant to look like the half dozen other identical bridges that this company advertises on their website.

This bridge has all the beauty of the Leverett Connector and 6 times the cost.
 

ceo

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The entire point of accelerated bridge construction is being able to replace the bridge rapidly, with a minimal shutdown time. Since the piers were being replaced (which I'm assuming was necessary), that was not an option, so they had to build the temporary bridge. At that point you might as well take the time to build it by conventional methods and save the cost.

Other than that, I'm not actually sure what we're disagreeing about here. It's a shitty design (speaking as a non-bridge-engineer); at the very least I don't know why the girders didn't have preinstalled flanges to bolt the diaphragms to, so they wouldn't have to do full-depth welding in the field. Even better, they could have used single full-width piers and avoided the problem entirely. And yes, for all that it's not a particularly visually inspiring bridge, particularly from the perspective of driving over it (what is that weird canopy-ish thing supposed to be, anyway?)
 

AmericanFolkLegend

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No such thing as "aesthetic tub girders." This is a highway overpass.

Heating and cooling of welds is an issue that has been known about for at least 80 years.

Again, for the middling design goal, this could have been done in a single week.
From the National Steel Bridge Alliance guide to tub girder bridge design:
One of the reasons most often cited for using steel tub girders is aesthetics. Bracing, stiffeners, utilities, and other components are typically hidden within the box, resulting in a smooth, uncluttered form. Because a single tub girder can essentially take the place of two plate girders, the number of visible components is minimized, again leading to a reduction in visual clutter.
You can say that you don't agree that tub girders look nicer, but they literally had a design competition for this bridge and the city insisted on taking into consideration aesthetics from below. Hence the tub girders and independent bridge piers.

And comparing a highway overpass to a 1,110' bridge over a navigable waterway is silly. There are dozens of contractors that can build highway overpasses in MA. There are probably only 3 or 4 contractors in MA that can build a bridge of this size over the mouth of the Charles River. JF White is certainly one of the contractor's on that short list. There were just design or fabrication problems with the welds in this case.
 

king_vibe

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You mean the people who sell tub girder bridges want you to believe that tub girder bridges are handsome?
 

BeyondRevenue

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You mean the people who sell tub girder bridges want you to believe that tub girder bridges are handsome?
On a beauty scale where 1 is a MASSDOT standard I-beamed concrete block highway bridge, and 10 being a sleek Calatrava looking floating arc, this bridge comes in at a solid 5 at least. Beauty is subjective.
 

chrisbrat

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It's interesting how the triangular piers on the new bridge complement the triangular towers on the Zakim Bridge
Yeah, I think it's a gorgeous and thoughtful design. Too bad it, yknow, didn't work IRL.
 

Delvin4519

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New article today from StreetsBLOG MASS writes about dedicated bus lanes on the North Washington St. Bridge, re: increased bus service frequency in Charlestown, and more reliable 111 bus service w/ a City Sq. stop.


Current bus lane configuration results in lengthy traffic delays for Chelsea riders and infrequent, every 45 minute or hourly bus service in Charlestown. (Note: currently, Charlestown buses service Downtown Crossing, travel congested and a factor for reduced frequency and longer headways today)
 

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