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Author Topic: A bridge that was once a cable stayed bridge that is no longer  (Read 2824 times)

roadman65

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http://commons.wikimedia.org/wiki/File:Stations_de_l%27Expo-Express_aux_%C3%AEles_Sainte-H%C3%A9l%C3%A8ne_et_Notre-Dame..jpg
http://expo67.ncf.ca/bernard_barham_expo_express_expo67.html

A while ago a I asked a question about why this bridge that goes between two islands in the middle of the St. Lawrence River in Montreal had its cables removed.   Some of you did not believe me that it was a cabled stayed bridge as you can definitely see in the above photo. 

Anyway, here is the bridge now from GSV https://www.google.com/maps/place/Montreal,+QC/@45.508194,-73.531943,3a,75y,90h,90t/data=!3m4!1e1!3m2!1soVPwLTYsovXlxHyA0i30XA!2e0!4m2!3m1!1s0x4cc91a541c64b70d:0x654e3138211fefef without the cables, but the tall towers still stand as it was when is supported the cables.

The only theory I can think of is that the cables were used to help with the added weight of the Expo Express Trains that also crossed the bridge during the 67 Expo that ran along the bridge then.  As you can see the bridge was amidst the Expo 67 in the wiki photo I have with all of the attractions surrounding it of the event.
« Last Edit: April 19, 2014, 05:46:24 PM by roadman65 »
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Sheryl Crowe

Jardine

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Re: A bridge that was once a cable stayed bridge that is no longer
« Reply #1 on: April 20, 2014, 02:04:53 AM »

I've googled several pictures of the bridge, and granted, I'm pushing 60 and don't have the eyesight I had when I was young, and I also have a cheap lap top these days, but:

it looks like the cables came down, and piers went in under the span where the cables attached to the stringers.



If that is the case, it would be a substantial modification (read that as expensive) to an existing structure.   I'd even go so far as to say the weight limit for the bridge with the new piers would be higher than with the cable stays.


Fascinating.  Thanx for calling this to our attention.
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webfil

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Re: A bridge that was once a cable stayed bridge that is no longer
« Reply #2 on: April 20, 2014, 11:33:33 AM »

You already have the answers to your questions in the old topic : www.aaroads.com/forum/index.php?topic=4443.msg97325

The deck was rebuilt and new design eliminated the need for suspension.

Some of you did not believe me that it was a cabled stayed bridge as you can definitely see in the above photo. 
Really?
I noticed that the bridge that carries a local street between Sainte Helene Island and Notre Dame Island  in Montreal was once a cable stayed bridge back during the 67 Expo and now the towers are still up but no cables.  I am guessing that it had to do with the fact that the Expo Express, that was a rapid transit train that was used during the Expo, is no longer tracked on that bridge anymore.   It used to cross the waterway there with the car roadway along side. The train cars obviously weighed plenty and being the lack of piers under the bridge it needed the cables as well as provide the "Bridge of the Future' at this World's Fair. Then again it might not be but a facade.

If you look at old photos of the Fair and go to Google street view for the latest you will see the change.

For those who are wondering, he's talking about Pont des Îles, located just after Pont de la Concorde, on Avenue Pierre-Dupuy.

http://maps.google.com/?om=1&t=h&ll=45.506467,-73.537674&spn=0.016572,0.034761
Most of the weight of a bridge is the dead weight - the bridge structure itself. A train is a significant live load but not to the same degree. I haven't heard of a cable stayed bridge being built to stand up without the cables - something seems wrong here. The structure itself ought to require cables just to handle the dead load, or else it was overbuilt to the point that the cables weren't necessary in the first place.
According to this page and this one, Pont des Îles had to be rebuilt in 1997 because of a structural failure, and that would have been when the cables were removed. The bridge was converted from hybrid rail/road to road-only in 1975.

The deck is still 94 feet wide (5 lanes + 1 bike lane + 2 sidewalks) after reconstruction, even though it bears 2500-3000 vehicles per day. The maximum density of the road is at least 5 times its peak density, and its capacity is at least 10 times the actual rates, according to a recent study by Dessau.

Some illuminatus proposed a tunnel under the seaway canal to link downtown Montréal with south shore using the Pont des Îles : Tunnel Centre-Ville - The Way Ahead.
« Last Edit: April 20, 2014, 11:37:16 AM by webfil »
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roadman65

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Re: A bridge that was once a cable stayed bridge that is no longer
« Reply #3 on: April 20, 2014, 11:50:09 AM »

Actually at first I one person doubted at the time.  I actually forgot about the topic a short while later, and did not realize that others posted to support my point.

Most likely it is because usually I do not post in Canada, so I never checked back later on to see like I do with the usual.  Lately I have been lucky if I could stay on for more than it takes to post my latest flickr update, but yes I should have checked back, but it is good to learn about what happened to that particular bridge since the World's Fair ended.  It is interesting to see at the east end where the roadway divides, where the old track grade went in the GSV image though.

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Re: A bridge that was once a cable stayed bridge that is no longer
« Reply #4 on: May 11, 2014, 10:21:02 AM »

I biked over that bridge back in 2011.  Noted the towers, but thought it was just some ornamental thing at the time.
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