A bridge too far?

[Kirbstone]

As a frustrated would-be engineer/architect I am always fascinated by such projects wherever they are.

In my lifetime in Ireland they are unlikely to undertake anything else on this scale and I have been collecting published photos of its progress over the past two years. They are now nearing completion and envisage opening this bridge to traffic at the end of this year.

Today I took the opportunity in indifferent weather to drive down there and see it for myself. It's a high level extrados concrete beam bridge over the tidal river Barrow South of New Ross almost a kilometer long and high enough for the famine ship Dunbrody, a three-masted barque to sail out under it.

I'm getting good at 'selfies' now.

Tom

[Ray]

I’ve been reading about it. It’s a fine looking bridge. It will look splendid when completed. Good old cantilever - or how to make things hang well. Talking of which, I like the kilt rig!

[dillon]

I like it.

[dillon]

https://www.google.com/search?rlz=1C9BK ... -QdelL54M:

The second of the I-140 bridges. These were built by a special machine that extended progressively across miles of estuarial wetlands in order to minimize construction disturbance. Expensive but essential, .and beautiful.

[crfriend]

As a frustrated would-be engineer/architect I am always fascinated by such projects wherever they are.

Yep. I'll take the "Me too!" route here as well.

What's astonishing in this case is that the towers that will eventually hold the cable-stays are still a-building whilst the arms that will form the deck are already being constructed -- and it's quite clear that this is no normal reinforced-concrete design; this bad boy is a highly-engineered pre-stressed work in which every possible force has been worked out well in advance. However, those towers will absolutely need to be complete and have the cables lovingly balanced atop them before they'll ever close the gaps or traffic will ever flow!

I'm getting good at 'selfies' now.

That's a nice-looking kilt-rig to be sure, but this engineer's brain was looking upwards at the structure under construction.

[beachlion]

I found the bridge under construction on Google Earth. It looks like an OOPS-moment. I think they can save the day with a sharp S-bend.

Bridge Ireland.jpg

Maybe the software of Google Earth needs some tweeking.

[crfriend]

I found the bridge under construction on Google Earth. It looks like an OOPS-moment. I think they can save the day with a sharp S-bend.

Somebody botched the seaming of the aerial imagery. The image you're looking at is a composite of at least two different aerial photographs. What gives that away? The shadows. Look at the shadow on the west bank of the river and then compare it to that of the one on the east side of the river. Not only is it different times of day, it's also probably different times of the year. In this endeavour, back out a few degrees of zoom and look for straight edges of difference; that'll yield clues as to when the photos were taken -- and that area looks like quite the patchwork.

Maybe the software of Google Earth needs some tweeking.

That'd be my guess.

[beachlion]

If you try to make a panorama picture, you need some overlap on the sides between the images. The software wil find the common elements in the pictures and "melt" them together.

In this case the right hand bridgehead was from a different run as can be seen from the lighter shade of the muddy waters beside the differences in the shadows. Because of the opening there were no common elements to use for the marriage of the images.

I like pulling legs. Not only on the Internet but also in the meat space. Not everybody appreciates my outrageous stories, told with a poker face.

[Kirbstone]

A very good observation and point, Carl, demonstrating just how inaccurate the published satellite imagery can be on google maps.

When tenders came in way back in the '70s for the construction of the Channel Tunnel the major construction consortia quoted mega millions, whereas the noted South African contractor Von der Merva quoted only several hundred thousand for the job. Incredulous Dept of Transport officials interviewed this Mr. Von der Merva and asked him just how he proposed building the tunnel for so little money. Mr. Von der Merva replied that he'd put a gang of kafirs on the French bank with instructions to dig towards England, with a similar gang on the White cliffs instructed to dig towards France.

One bright Govt official then asked Mr Von der Merva what would happen if his gangs didn't meet in the middle?, to which Mr Von der Merva replied that they'd end up with two tunnels for the price of one!.....So it would appear from the Google Maps pics that Counties Kilkenny and Wexford were about to have each a bridge of their own !

What IS very interesting is how they leveled up the sections vertically when they did meet, with a vertical disparity of around 120Cm or about 4 feet due to the central cantilevers having more 'sag'. They must have had it all pre-calculated of course, for there appeared a pair of socking great 6-ft-high black girders which fitted over prepared holes in the deck and they wound the sections level before doing the last joining concrete pour. No doubt they fiddled about with the cable tensions as well. The result now is a smooth uninterrupted sweep of deck from one end to the other.

Tom

[Kirbstone]

Further pics....

Bottom pic shows two of three stabilizing pillars due to be demolished now the deck is complete.

[beachlion]

Thanks. I love those big builds. Not only for the technical and engineering aspects but also for the whole organisation with sub-contractors and sub-sub-contractors. I made a slight contribution to a few of the socalled Delta-Works in the Netherlands. Those mega-projects are supposed to protect the country from flooding.

https://en.wikipedia.org/wiki/Delta_Works

[denimini]

I found the bridge under construction on Google Earth. It looks like an OOPS-moment. I think they can save the day with a sharp S-bend.

If they just continue on - will probably need two lanes anyway

[dillon]

https://www.google.com/search?rlz=1C9BK ... -QdelL54M:

The second of the I-140 bridges. These were built by a special machine that extended progressively across miles of estuarial wetlands in order to minimize construction disturbance. Expensive but essential, .and beautiful.

Same company built the US17 bypass bridge at Washington NC:

http://utcdb.fiu.edu/bridgeitem?id=231

[pleated]

The Rose Fitzgerald Kennedy Bridge, New Ross, Co. Wexford.
https://www.youtube.com/watch?v=xemK_TdhqWU
5.01

N25 Progress June 2019
https://www.youtube.com/watch?v=o09FFFHl4os
4.12

[crfriend]

Thank you -- very much -- for those two links, Pleated.

I can say, without any shame whatsoever, that I watched both of those slack-jawed and with tears running down my cheeks for the stunning beauty of what we as mankind can create out of stone and steel, and wood and wire (to steal a lyric from Bill Staines) . Not only does that exemplify what we can do when we put our heads to it, it was also a damned fine correlation of good music and extreme flying on the part of the helicopter pilot.

I wish we could do the same here where I live.

A long time ago (and it feels like it was in a galaxy far, far away) I worked for an engineering firm in Boston, and we had the design contract for the I-90/I-93 interchange in Boston several hundred yards from my office. One of the grandest joys of my life was taking the commuter train from Worcester to Boston and then back home again and watching that design that I in a small way helped enable (by keeping all the computers running) take shape and seeing it happen day by day. That was definitely one of the high points in my career.