After reading about railroads in Iowa and North Dakota being in a serious jam after loosing just one bridge on their line, it makes me wonder if a bridge could be built that water could not wash out. That said, I’m not an engineer nor have I built any bridges bigger than the Erector set one I built over my queen size bed 20 years ago. Would it be possible on shorter bridges to pour one continious piece of re-enforced cement that went under the bridge and formed the bottom of the creek 30 feet upstream and 30 feet downstream of the bridge… And formed the supports for both ends of the bridge.
The Army Corps is gonna look at you hard. Things like that are already causing a big part of the problem as basins are silting-in, the thalweg is getting aimed under the bridges by floodwalls, berms, etc, and the natural meanders are disappearing. (In one regard, you are slowing the river down by damming it, etc. (which speeds up sedimentation), but also by forcing it into one channel you create a loaded gun by not being able to dissapate the energy of fast moving high water.
The cause and effect will have the Army looking at you warilly from the word go. Better to armor the bents in the bridge, create as much freeboard as you can and move on.
(If the water can’t go under the bridge, it will find a way to cut around it and wash out the approaches)
…{non railroad}…Anyone interested in bridges of massive category, take a look at the one being built to bypass Hoover dam {Highway 93}…Wild…!
Sure, that can be done. How much money do you have ?
That’s really the toughest consideration in most engineering projects, and esp. bridges - balancing the trade-off between the low risk of a rare and random event or loading occurring, with the cost of beefing it up enough to reliably handle that event or loading without a failure. A lot of that depends on the consequences of the likely failure - losing a bridge usually involves just the cost of replacing it plus detours &etc. in the meantime, whereas the failure of a dam could destroy entire towns downstream and kill dozens or hundreds of people. So a lot more attention and money should be put into the design and construction of the dam than the bridge. Exactly how much more is a matter of standards, codes, experience, professional engineering judgment, etc.
Most railroad bridges were and are very conservatively designed and built, so the loss of one due to flooding as you point out is notably rare. The usual mechanisms of failure are predictable, as are the counter-measures, as follows:
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Water pressure in the downstream direction from the force of the flowing water overturning the piers. Fortunately, the piers are usually narrow, long, and heavy enough with the weight of the bridge on them to easily prevent that.
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Same, but now with the water high enough to impact the bridge’s superstructure = the main horizontal part of the bridge. That’s far worse, because: a) the bridge then has a much larger surface area exposed to the water - a lot wider than the piers, and with a considerabe height aspect; and, b) the wa
Thats small potatos, try these:
to be built in Dubai and:
the Millieu Viaduct in France
ANYTHING can be done if you commit enough resources to it.
A little bit OT but still rail and bridge related, worlds highest rail bridge under construction…in India!
Rendering:
Eiffel would be proud!
We all realize the new one constructed in France is wild, but the Hoover Dam bypass unit is not “small potatoes” by any standard. If you have been watching it being constructed in the past 2 years plus, you already know that…
The Black Canyon bridge is a biggie, but compared to Millieu its a footbridge! I dont like the way the bridge destroys the famous view of the dam but hey thats life. BTW have you seen the Oakland Bay Bridge replacement? already well under construction, say goodbye to the truss sections:
Sorry, can’t buy any assessment of the Hoover Dam bypass bridge as being anything except extraordinary in construction difficulty and scope.
On the replacement bridge you mention, I have not followed it’s contstruction. The above one, I have.
Cool new bridges going up that make bridge engineers drool, but back to the original question.
As Paul and Mudchicken have alluded to, even if you had the money, Mother Nature is still the bigger player here. In AREMA’s Scour Seminar, which I co-teach, we have too many examples of why it’s not nice to fool Mother Nature.
Flowing water, over time, will pretty much always go wherever it wants to go, no matter what us puny humans try to do with it. We keep trying to learn how to beat her, we we never quite get there.
The Schoharie Creek (in NY state) bridge collapse on April 5, 1987 cost 10 lives and led the FHWA to develop HEC-18 as a means to determine sour at bridges.
The Hatchie River (near Covington, TN) bridge failure of April 1, 1989 cost 8 lives and led the FHWA to develop HEC-20 to try to handle on streambed stability.
We are always playing catch up. We too often focus on just the site of the bridge when we really need to look at it from about 30,000 feet to see where the river was and where it will be trying to go. How many bridges have you seen with the stream not in the center? Chances are, when the bridge was built it was. Guess which moved.
Ever wonder why there are relatively few bridges over the Mississippi River? Talk about a river that moves!. You have to step back a long way to find stable ground to start your bridge and then look for something hard to put it on when you get into the water (depths to rock get pretty dramatic) and you just watch the dollar figure climb.
Lots of fun things to consider if you want to build a bridge, aren’t there?
I’m sorry…I saw this post this morning, before anyone replied to it. I’m no engineer, but I figured that MC would have most of the answers. In Mr. Boyd’s defense, however, I want you all to note that he’s from Stillwater, Minnesota.
If you’re going to put concrete under the waterway, it might make more sense to put the railroad underneath as well. They’re called aqueducts, and not all of them were built by ancient Romans.
Or a tunnel. Examples of those for mainline railroads (not transit) under rivers are the PRR’s (now Amtrak) under the Hudson (North) River and East River at New York City, the CN and CPR tunnels under the Detroit River at St. Clair, and perhaps some others that I can’t think of right now.
Although most of the justification for these tunnels instead of bridges was because of the long open water spans and heavy shipping traffic at the site, the East River is notorious for its fast running currents from the tide changes - that’s why the Hell Gate Bridge was built with its main piers on the banks. The Detroit River tunnels are similar in that potential ice jam situations could be deadly to the piers of a fixed bridge - recall that a major bridge across the Niagara River just below the Niagara Falls (not sure if it carried railroads or not) was lost to that cause.
- Paul North.
PAUL DN: Wasn’t the now KCS bridge over the Mississippi at Vicksburg closed for a while because of scoring of one pier? Seem to recall if it hadn’t been found when it was the bridge could have been lost?
This superbridge that I am envisioning would have the creek or small rivers bottom dug down before the cement creek/river floor portion is poured. So essentially when finished it would mimic the shape of the original creek/river floor and not restrict water flow more than what it was before the project. Sure its expensive, but I bet the RR up in North Dakota mentioned in the latest Trains mag is spending expensive $$$ running around their washed out bridge plus all the other hassles they have that are other byproducts.
The engineers on this thread have it right, Nature can be delayed but not defeated. With all due respects to Boyd, his thinking is philosophically similar to that which stated that the RMS Titanic was unsinkable.
Each bridge location, and thus each bridge, is unique to that given location. It may be a similar bridge to another, but somethng about it makes it different, like snow flakes. The best bridge application to a given location and purpose is used but sooner or later, be it age and deterioration, increasing load factors, changes in the what goes over or under, or acts of nature, its falibility point may be reached. Sometimes its caught before it happens, sometimes it happens by storm.
What you’re describing is essentially a giant closed-cell box culvert. Yes, the bottom would function hydraulically as well as the original stream bottom - probably better since it would be smoother. But that’s only 1 part of the analysis, and even that has negative implications for the downstream land and people, such as: “What - now you’re going to make the water flow at me faster ?!?” Greatly simplified, anymore as a practical matter you can’t do anything in a stream bed that will either slow down or speed up or restrict or channelize the stream flow in any respect - it pretty much has to stay just as it is today in all aspects.
Your proposal also not going to solve the tipping or overturning problem when the water gets up to the superstructure’s level, unless you either raise the bridge quite a bit, or make it hugely wide in the downstream direction for stability, and/ or the upstream direction for a counterbalance weight (kind of like an outrigger canoe).
But trumping all of this are going to be the environmental and permitting considerations, which are key. What you’re proposing will have an HUGE impact on the aquatic life in and on the streambed during and after the construction, as well as the fish, etc. in the streamwater. For any major stream there’s going to be opposition to al
I know that bridge from being there many years ago, but do not recall reading or hearing about that happening. Which simply means that it may well have occurred, but I missed it. Perhaps steve14 (above) - who quite probably is better informed on such current events than me - has more information, but I do not.
- PDN.
I remember hearing something about a pier problem there and at another highway bridge over the MIssissippi further north. Both seemed to be foundation stability issues. The highway had, or still has, significant movement of a pier.
I’ll check with a couple of my sources and get back to everyone
They are in a serious jam because they don’t have the money to replace a “mere mortal” bridge. If they can’t afford a mere mortal bridge, how are they going to afford a “superbridge”.
Regardless of how super the bridge is, water can destroy it. It can over whelm it, it can over top it, it can corrode it, it can undermine it. Its just a matter of time.
The mere mortal bridges they lost were probably standing for 50-100 years. chance are they don’t really need a super bridge, just to replace the mere mortal bridge with another mortal one, just a little more buff.