30-01-2007, 17:26 | #21 |
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30-01-2007, 17:36 | #22 |
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Then you have three problems
1) Very very long bridge 2) Shipping clearances 3) Existing station is left unserved Fact is we will have to accept that sometime in the next 25-50 years it will have to be replaced and it won't be nice for commuters |
30-01-2007, 23:16 | #23 |
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The original bridge was replaced by building the new one inside the old one than removing the old one between 1930 and 1932. This was done using a moving gantry over the bridge, allowing trains to run underneath while construction took place.
I presume quite a few weekend closures were needed, though. I have some photographs of the construction if anyone is interested. |
31-01-2007, 11:43 | #24 | |
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Maybe sooner, if electric motive power becomes standard intercity. Cross beams probably would not give adequate clearance for overhead supply. New structure would seem most economic and less disruptive of service, existing being retained for future upgrading or third line. Existing rail allignment and station location indicates position quite near existing viaduct. East would interfer least with view of existing from Drogheda side. Cable stayed bridge would least block view from west. Contrast old/new would make aesthetic statement. http://www.roughanodonovan.com/Publi...R%20030303.PDF Boyne bridge on M1 cost €35m, 350m long overall, 170m main span , six traffic lanes wide. Maybe Transport 21+? |
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31-01-2007, 13:31 | #25 | |
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Ideally I would continue everything BUT intercitys (Enterprise) and freight through the current bridge. Last edited by Mark : 31-01-2007 at 13:44. |
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31-01-2007, 13:59 | #26 |
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If there was any kind of joined up thinking in this country the M1 viaduct could have had a train deck. I travel across one morning and evening - designed 1918, decades before the subway eventually ran in 1966! The M1 viaduct is 140m shorter and 20m closer to the ground so you never know what could have been accomplished.
http://en.wikipedia.org/wiki/Prince_Edward_Viaduct |
31-01-2007, 14:51 | #27 |
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Off topic:
I went across that bridge (by subway) a few times a week for a year and never knew it was called Prince Edward! One of the bridges from Angelsey into 'mainland' Wales has something similar - road upstairs, main train line downstairs. It was substantially rebuilt in the mid 70s after a fire. The road was only added in the rebuild. http://en.wikipedia.org/wiki/Britannia_Bridge /Off topic |
31-01-2007, 17:14 | #28 |
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packetswitch - pick 100 of your fellow subway riders and I bet maybe 1 or 2 could give it the right name - I wouldn't know except for wikipedia.
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01-02-2007, 10:15 | #29 |
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Isnt there a similar situation in Newcastle, England?
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02-02-2007, 13:56 | #30 |
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think this is the one you mean Thomas
http://en.wikipedia.org/wiki/High_Level_Bridge |
02-02-2007, 19:24 | #31 |
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The Brittania bridge is amazing, its a pitty the rail users and the people in their cars cant see those lions anymore. Or aprciate how much a nod the bridge was to eygptian architecture. One other thing that came to mind with replacing the viaduct would be supper strong plastics or silicon. But most likely it'd be carbon or steel yet again.
The height of the bridge only matters now because of the valley, theres no tall masted ships of the royal merchant navy sailing under it anymore, and the port isnt that important. That and with the world temp set to increase, its the only water front building likely to not need flood protection in Drogeda.
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02-02-2007, 19:51 | #32 |
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1. I can assure you that the rail users see the lions, on both ends in fact, as long as you know when to look out the window. They are cool.
2. (back on topic) If you were the Chief Consultant on the Drogheda Bridge Study Scheme what would your preferred option be? |
03-02-2007, 11:41 | #33 | |
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I think the original iron lattice bridge looked really elegant. I would build a new central span out of modern materials, and make it wide enough for two trains to pass, and strong enough to carry a pair of 201 led Enterprises. I think strengthening work might also be needed on the viaduct. I think it should be possible to build new latticework outside the current structure in much the same way as the current bridge structure was built inside the original one. |
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03-02-2007, 16:49 | #34 |
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Back off the topic, the whole not being able to see lions is sapossed to be through as the new structure of the bridge has left them out of view. Well according to some bbc documentry i saw a while back.
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