Recently, as a result of Hurricane Sandy, a pipe burst on the MTA's Canarsie Line. That is one example of the problems the Transit Authority is still working with. And as a new hurricane season approaches there are a great many prevention projects that are incomplete. Current status is reported in today's edition of the New York Times. Here is the link: http://www.nytimes.com/2013/05/17/nyregion/for-now-mtas-flooding-plan-still-relies-on-sandbags-and-plywood.html?ref=nyregion&_r=0
John WR Recently, as a result of Hurricane Sandy, a pipe burst on the MTA's Canarsie Line. That is one example of the problems the Transit Authority is still working with. And as a new hurricane season approaches there are a great many prevention projects that are incomplete. Current status is reported in today's edition of the New York Times. Here is the link: http://www.nytimes.com/2013/05/17/nyregion/for-now-mtas-flooding-plan-still-relies-on-sandbags-and-plywood.html?ref=nyregion&_r=0
Recently, as a result of Hurricane Sandy, a pipe burst on the MTA's Canarsie Line. That is one example of the problems the Transit Authority is still working with. And as a new hurricane season approaches there are a great many prevention projects that are incomplete. Current status is reported in today's edition of the New York Times. Here is the link:
http://www.nytimes.com/2013/05/17/nyregion/for-now-mtas-flooding-plan-still-relies-on-sandbags-and-plywood.html?ref=nyregion&_r=0
It does take time to harden open locations and probably each potential entry point for sea water requires different engineering. South Ferry the unsecured timbers that punched thru the plywood could happen anywhere. I would expect MTA might uses steel plates at especially vulnerable locations will be used. Plates can also be made larger reducing need for sand bags.as well ! !
Flood gates at all tunnels may require additional real estate and engineering. These gates are especially needed including the East river and North river tunnels of Amtrak !
blue streak 1Flood gates at all tunnels may require additional real estate and engineering. These gates are especially needed including the East river and North river tunnels of Amtrak !
I'm sure putting up permanent gates is a lot more complicated and initially more expensive that putting up plywood and sand bags in an emergency. And I'm also sure it will come in time. In the meantime we can hope we do not get another Sandy this year.
Somewhere elsewhere in websurfingland I saw a visual of a proposed tunnel cork to meet this requirement. The thing appeared to be inflatable. Don't know if it's supposed to be fixed or portable.
So, how much leakage can be allowed past third rail structure, handrails and such before the drain pumps get overwhelmed?
For a fixed-point defense, I would vote for some kind of vertical guillotine blade that would drop down fixed tracks in the tunnel structure - rather like an old-style gate valve.
Chuck
tomikawaTT Somewhere elsewhere in websurfingland I saw a visual of a proposed tunnel cork to meet this requirement. The thing appeared to be inflatable. Don't know if it's supposed to be fixed or portable.
Two general styles: One is a fixed gate structure with inflatable 'skirts' for sealing; the other is fully inflatable in sections with an internal stiffening and tension-member frame. Both are essentially 'portable' in that they are only deployed where and as needed. In my opinion, it helps to have as little an inflatable volume as possible, because that simplifies inflating with normal rail brake air. In my opinion, there is a benefit in designing the things so they can be installed from the 'dry' side in case of emergency flooding, or effectively placed and actuated with some amount of standing or flowing water already present. (This brings up the provision of rail equipment that can operate reliably in several feet of depth, of brackish or salt water... or have skirts and perhaps propulsive motors allowing operation as a sort of barge if unexpected flood levels occur... )
I feel that the approach 'works' best when the walls and floor of the tunnel are designed to accommodate good sealing, or have a section particularly designed to help provide a good seal. A cast-concrete portal frame with corrugated surface that matches the face of the inflatable seal is one approach; the surface continues horizontally across the track like a grade crossing, with only a clearance for the railhead and flangeway. The seats and seal faces can be angled to provide better pressure resistance. You can also provide footings or sockets for reinforcing framework behind the face of the plug (anyone living in NYC in the Seventies may remember the general principle involved in protecting their doors! ;-} )
Guillotine 'watertight doors' are a reasonable idea, but would need to be maintained and kept free of trash, and pose a risk if deployed at the 'wrong' time (e.g. with a train underneath). Might be better to use the system that is used at some river levees, where the panels are only brought in and placed in the slots when needed.
While it may be possible to operate trains right up to the point a powered gate would need to be closed, I think there would be adequate time in most storms to stop train service and emplace and inflate 'corks.' Of course, after the flood, the time to inspect and repair the flooded section of track is far greater than the time to strike the plug arrangements...
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