AARoads Forum

National Boards => Bridges => Topic started by: roadman65 on December 04, 2015, 12:55:52 PM

Title: Bridges with cables that drop below road deck
Post by: roadman65 on December 04, 2015, 12:55:52 PM
I was noticing that on the Bear Mountain Bridge in New York that the cables drop below the roadway.  I have seen that design before on some other suspension bridges as well.  To me that seems kind of weird that they would construct the bridge this way being that its all to be suspended from below the cables from suspenders.

Not only that but it increases the load as the cables themselves are supporting the truss that houses the bridge's deck.  The whole roadway is being held in place from the cables below it instead of above it which does not allow the give that having it suspended above has such as when the bridge sways in the wind etc.
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 04, 2015, 01:57:20 PM
Brooklyn Bridge would be the 'classic' example.
Title: Re: Bridges with cables that drop below road deck
Post by: SteveG1988 on December 05, 2015, 10:41:34 PM
Riegelsville Bridge in NJ/PA.
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 05, 2015, 10:50:04 PM
Quote from: SteveG1988 on December 05, 2015, 10:41:34 PM
Riegelsville Bridge in NJ/PA.

wow!

From what I've read about the San Francisco/Oakland Bay Bridge suspension spans, I wasn't aware anyone had tried a multispan suspension bridge without intermediate anchorage(s).

Wonder how asymmetrically that one could be loaded and not fail ??
Title: Re: Bridges with cables that drop below road deck
Post by: SteveG1988 on December 07, 2015, 09:15:09 AM
Robeling Aqueduct over the delaware river.
Title: Re: Bridges with cables that drop below road deck
Post by: BrianP on December 07, 2015, 04:53:51 PM
I think the three given above would be examples where the cables go to the road level but not below the road level like the OP.

Bear Mountain Bridge (https://www.google.com/maps/@41.32114,-73.9824802,3a,75y,214.83h,99.2t/data=!3m7!1e1!3m5!1sdaxcHdk1tkHDKKEJ5VxP3Q!2e0!6s%2F%2Fgeo1.ggpht.com%2Fcbk%3Fpanoid%3DdaxcHdk1tkHDKKEJ5VxP3Q%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D81.101036%26pitch%3D0!7i13312!8i6656)

http://media.lehighvalleylive.com/upper-bucks_impact/photo/riegelsvillebridgejpg-b6c0af9b42ad528f.jpg

http://3.bp.blogspot.com/-O3_rSTe-rRg/UUHmRL_elGI/AAAAAAAAAOU/hbsQzd1f8o0/s1600/Roebling+Aqueduct+cutaway.jpg

http://static.turistipercaso.it/image/b/brooklyn/brooklyn_dbg7x.T0.jpg
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 07, 2015, 05:22:03 PM
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2F3.bp.blogspot.com%2F-KgsmsEBQxSU%2FT5EGF2NMn-I%2FAAAAAAAAABM%2FNRUhBsiBWt4%2Fs1600%2Fbase%2B01.jpg&hash=d95c32170cfd01e6c9692bb59a23cd29209507b0)
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 07, 2015, 05:22:40 PM
{couldn't get pick to post, check out cable sag near anchorages on the Brooklyn Bridge}

{nevermind, figured it out}
Title: Re: Bridges with cables that drop below road deck
Post by: BrianP on December 07, 2015, 05:33:43 PM
Well any suspension bridge will have the cables go below the road deck near the anchorages  since the anchorages are below the road.  I think the original point was geared more towards mid span.
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 07, 2015, 07:14:08 PM
These drop down and head back up, it's really an interesting feature.

Totally unlike, for example, the Golden Gate.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.pindelski.org%2FBlog%2FGGB_06.jpg&hash=71b6e091a70dbfabfb9b58c72fdcfd7aa0378920)
Title: Re: Bridges with cables that drop below road deck
Post by: Rothman on December 09, 2015, 02:30:26 PM
Quote from: SteveG1988 on December 07, 2015, 09:15:09 AM
Robeling Aqueduct over the delaware river.

Really?  The deck actually sits far below the top trusses.

Drove across it myself. :D
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 09, 2015, 11:03:02 PM
How does it even occur to someone to make an aqueduct with a suspended span ??

  :biggrin:
Title: Re: Bridges with cables that drop below road deck
Post by: SteveG1988 on December 17, 2015, 02:03:25 PM
Quote from: Rothman on December 09, 2015, 02:30:26 PM
Quote from: SteveG1988 on December 07, 2015, 09:15:09 AM
Robeling Aqueduct over the delaware river.

Really?  The deck actually sits far below the top trusses.

Drove across it myself. :D
Quote from: Jardine on December 09, 2015, 11:03:02 PM
How does it even occur to someone to make an aqueduct with a suspended span ??

  :biggrin:

I was wrong, i thought they went way below instead of just to the deck.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fhalfwaybrook.com%2Fwp-content%2Fuploads%2F140681roebling.jpg&hash=72df8ceb435782378b5c0ed4ef63c83716434b00)

And It was made as a suspension span as a way to prove Robeling's Wire Rope.
Title: Re: Bridges with cables that drop below road deck
Post by: Pete from Boston on December 17, 2015, 02:09:34 PM

Quote from: Jardine on December 07, 2015, 05:22:03 PM
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2F3.bp.blogspot.com%2F-KgsmsEBQxSU%2FT5EGF2NMn-I%2FAAAAAAAAABM%2FNRUhBsiBWt4%2Fs1600%2Fbase%2B01.jpg&hash=d95c32170cfd01e6c9692bb59a23cd29209507b0)

Brings a whole new meaning to the term "ghost ramps."
Title: Re: Bridges with cables that drop below road deck
Post by: Jardine on December 17, 2015, 05:20:22 PM
It's a cool pic, just wish whomever took it had rolled his window down first.

:-o