North Washington St Bridge

Arlington

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I just realized that they took their design cue from the architectural masterpiece that is the TD Garden.
To me it seems an echo of the current bridge's center span. But really (and mostly) just a way to break up what's going to be a long bike/walk across the bridge into 3 phases rather than one long windswept span.
 

HelloBostonHi

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How many looked at this graphic in the approval process and no one caught the missing h in warf? :unsure: The replacement bridge looks fine and is a nice complement to the Zakim. How realistic is it though that trees will be planted on it?
The trees being part of the full replacement bridge is a key part of the design so I'd be surprised if they dropped them. They're making the sidewalk extra wide in that area and made a big point in the presentation about how unique it was and how they wanted to make a place mid bridge where people wanted to stop and sit and enjoy the view.
 

JeffDowntown

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The trees being part of the full replacement bridge is a key part of the design so I'd be surprised if they dropped them. They're making the sidewalk extra wide in that area and made a big point in the presentation about how unique it was and how they wanted to make a place mid bridge where people wanted to stop and sit and enjoy the view.
They will plant the trees, and they will be dead after the first deep freeze of the next winter. A planter box up in the air like that, with air flow on all sides, is going to freeze, killing the roots.
 

FK4

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They will plant the trees, and they will be dead after the first deep freeze of the next winter. A planter box up in the air like that, with air flow on all sides, is going to freeze, killing the roots.
Sadly true. Since this is a heavily used corridor for pedestrians, I think they should consider an alternative to keep people warm as they cross the Charles between Boston and Charlestown. I am including my own proposal below:

 

stellarfun

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They will plant the trees, and they will be dead after the first deep freeze of the next winter. A planter box up in the air like that, with air flow on all sides, is going to freeze, killing the roots.
^^^Not necessarily.



When water freezes, it gives up heat. The air temperature around a bridge over water would likely be warmer than if the same bridge was over land. The temperature of ocean water must fall to 28.8 F before it freezes.
 

whighlander

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^^^Not necessarily.



When water freezes, it gives up heat. The air temperature around a bridge over water would likely be warmer than if the same bridge was over land. The temperature of ocean water must fall to 28.8 F before it freezes.
Stellarfun -- Not necessarily -- as most things in the real world -- its a complex system and hence a non-simple answer

It depends a lot on the species of the tree and how it is treated

For example in a otherwise good environment trees from this kind of climate can take a lot -- we have a nice dwarf Japanese Maple in a fairly large pot -- it stays out all winter -- although we do bring the pot up to near the house for protection from the wind

Most temperate deciduous trees that perish in the winter suffer more from exposure [and dehydration -- that's why they drop their leaves] than they do from just freezing. In a urban environment close to a road the worst offender is the salt used to de-ice the roads. Put a big enough "Pot" on the bridge and make sure that the slush from the road doesn't end-up melting in the "pot" and there's a good chance that a native tree or one from our kind of climate will survive.
 

stick n move

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Since a temporary bridge still has to deal with the same forces as a normal bridge (minus 100 year storm design requirements etc Id guess) how underbuilt or different than a permanent bridge are they? Or do they still have to be able to withstand the same things.

What exactly makes them temporary, are they just designed to be able to disassemble fast? This looks pretty sturdy. Are there examples of temp bridges they just left as the regular bridge? This thing looks 10x sturdier than the bridge being replaced.

My guess is that the 2 main differences are 1. theyre ugly (function over form, exposed utilities etc), and 2. theyre designed to be disassembled easily, how close is this?
 
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iamdjmichael

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Since a temporary bridge still has to deal with the same forces as a normal bridge (minus 100 year storm design requirements etc Id guess) how underbuilt or different than a permanent bridge are they? Or do they still have to be able to withstand the same things.

What exactly makes them temporary, are they just designed to be able to disassemble fast? This looks pretty sturdy. Are there examples of temp bridges they just left as the regular bridge? This thing looks 10x sturdier than the bridge being replaced.

My guess is that the 2 main differences are 1. theyre ugly (function over form, exposed utilities etc), and 2. theyre designed to be disassembled easily, how close is this?
I believe the Rourke Bridge in Lowell is a temp bridge that was left as a permanent one. https://www.google.com/maps/@42.6382432,-71.3566827,3a,75y,14.37h,90t/data=!3m7!1e1!3m5!1sDf_EYyhSqfDI7PXhLTc6Kg!2e0!6s//geo1.ggpht.com/cbk?panoid=Df_EYyhSqfDI7PXhLTc6Kg&output=thumbnail&cb_client=search.revgeo_and_fetch.gps&thumb=2&w=96&h=64&yaw=14.370744&pitch=0&thumbfov=100!7i13312!8i6656
 

ceo

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Well, this temporary bridge a) is ugly, b) has this annoying double S-curve and c) will probably rust out in 10 years.
 

millerm277

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Since a temporary bridge still has to deal with the same forces as a normal bridge (minus 100 year storm design requirements etc Id guess) how underbuilt or different than a permanent bridge are they? Or do they still have to be able to withstand the same things.

What exactly makes them temporary, are they just designed to be able to disassemble fast? This looks pretty sturdy. Are there examples of temp bridges they just left as the regular bridge? This thing looks 10x sturdier than the bridge being replaced.

My guess is that the 2 main differences are 1. theyre ugly (function over form, exposed utilities etc), and 2. theyre designed to be disassembled easily, how close is this?
I think a major criteria you are missing is design life and maintenance considerations.

It's a temporary structure, so a lot of things that matter if you want it to stick around for a long time don't matter here. I don't know that a lot of that structure would hold up to the rest of the environment over a time period measured in decades (salt air/water and the rust/corrosion that results).

"Pound a big metal rod into the bedrock, leave it sitting in salt water" or whatever they've done there instead of what you typically see for bridge supports in water works fine for now, but seems like that wouldn't hold up for decades.

Those trusses (bailey bridge?) may be an easy to assemble prefab thing, but they also look like they'd be expensive to maintain over the long-term relative to other designs. There's a lot more structural elements and connections to have to inspect than you wind up with compared to the designs you see on most permanent structures.
 

BostonUrbEx

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The Salem Turnpike/Rt 107's Belden-Bly Bridge on the Saugus/Lynn line has been "temporary" for years, and there is zero construction going on to build the new bridge. We should do bets on whether the Rourke or Belden Bly will be replaced first.

 

cburns

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I think the biggest offender around here was the Fore River crossing. The original 1936 structure was closed in the late '90's. The "temporary" vertical lift bridge to carry 3A traffic stayed in place until the replacement span for the original opened in 2018.
 

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