Author Topic: INRD bridge problem?  (Read 1142 times)

crblue

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INRD bridge problem?
« on: August 28, 2019, 07:34:45 AM »
WISH TV is running a "news" story about problems with an INRD bridge over a county road in Monroe County. Local residents claim that chunks of concrete routinely fall off of the 102-year-old bridge.

https://www.wishtv.com/news/local-news/residents-chunks-of-concrete-falling-off-aging-railroad-bridge/

https://www.google.com/maps/place/39%C2%B006'31.7%22N+86%C2%B040'30.7%22W/@39.1087976,-86.6760527,356m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0x0!7e2!8m2!3d39.1087958!4d-86.675185

IN1312

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Re: INRD bridge problem?
« Reply #1 on: August 28, 2019, 01:06:22 PM »
This is one of the few roads in the area I have not been down, although I have not personally heard this bridge mentioned as a problem previously. Just to look at it, the outer elements of the concrete definitely look eroded. Can anyone who knows the engineering behind these bridges tell us how much this affects the integrity? I was under the impression they get their strength from the rebar, and the concrete was to protect the rebar from the elements.

rrnut282

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Re: INRD bridge problem?
« Reply #2 on: August 28, 2019, 01:46:00 PM »
Generally speaking, concrete is strong when it's compressed (something sitting on top of it) and very weak in tension (when something pulls on it).  Steel is good in compression and even better in tension.   A moving load (train) can go from being compression when over the supports to tension as it moves away from the supports.  Steel-reinforced concrete gives you the best of both. 
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crblue

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Re: INRD bridge problem?
« Reply #3 on: August 28, 2019, 05:36:08 PM »
When you put a downward, vertical load on a beam (which, sorta by definition, is horizontal), the beam will experience a compression load on the top and a tension load on the bottom. If you were to take a straw and place it horizontally between supports and then you press down on the straw between the supports, the middle of the straw will deflect downwards. That deflection causes the top surface of the straw to compress horizontally and the bottom surface of the straw to stretch (tension).

In a steel-reinforced concrete beam, the concrete takes the compression force and the steel reinforcing rods take the tension. If the beam is engineered correctly, a steel-reinforced concrete beam can take more load than a pure concrete beam can. And, to an extent, the beam retains its design strength even if pieces of concrete break off of the bottom of the beam.

Where steel-reinforced concrete beams get into trouble is when water gets in, such as through a crack or broken area. The steel will start to corrode which could weaken the beam.

All that said, you have to examine a bridge made with steel-reinforced concrete beams in order to determine which parts of the bridge are the beams and which parts are decking and side rails designed to retain whatever the bridge carries. In the case of a railroad bridge with ballast, the deck and the side rails have to retain the ballast, but it's still the beams that carry the load.

I have no reason to believe that INRD doesn't have a competent bridge engineer on staff or on contract. I feel confident that that bridge is inspected at regular intervals. I doubt that the bridge is in danger of collapsing. But, it's hard to convince lay people or the news media of that when they see pieces falling off of the bridge.

IU_Tower

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Re: INRD bridge problem?
« Reply #4 on: August 28, 2019, 09:31:11 PM »
FFS.... The "haunted bridge" in Avon has been dropping concrete chunks since at least the mid-80's and no one has even blinked....

doublestacks

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Re: INRD bridge problem?
« Reply #5 on: August 28, 2019, 10:05:05 PM »
when topics like this come up, you've got to love all the facebook certified bridge inspectors in the comments. ::) id say the most recent story would be about the rockville ave bridge, west of holt rd on the csx mainline. they all might look like crap but still hold.
« Last Edit: August 28, 2019, 10:16:11 PM by doublestacks »
Steel is real and it feels no pain.

Wema

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Re: INRD bridge problem?
« Reply #6 on: August 28, 2019, 10:12:19 PM »
Driving through downtown Indy daily, almost all the CSX underpasses look like this bridge and still hold up as well...  ;D

Kim_Heusel

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Re: INRD bridge problem?
« Reply #7 on: August 29, 2019, 12:23:03 AM »
The way I read the story, it seems people are mostly concerned about chunks of concrete falling off and striking someone below.

Kim Heusel

IN1312

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Re: INRD bridge problem?
« Reply #8 on: August 29, 2019, 01:59:14 AM »
So basically, NIMBY run wild in a community that teaches the fine art of using getting triggered to get your way?

DRLOCO

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Re: INRD bridge problem?
« Reply #9 on: August 29, 2019, 10:20:19 AM »
Facebook qualified Structural engineers aside, how'd you like it if a giant chunk of concrete fell on YOU or YOUR car?  Let's have some perspective here.  You'd be pretty pissed and want something to be done about it, right? 
SO, when the city says "hey, that's the railroad's problem..." People don't know how to contact the railroad, so they go to the news crews and facebooks...both of those sources just love a good scare story...and you see the shitshow that is created when that happens...
Professional Locomotive Engineer and train nerd with most social skills.

trainmaster53

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Re: INRD bridge problem?
« Reply #10 on: August 29, 2019, 01:14:34 PM »
For some reason this Story will not Print out either. I have checked out my Printer and it seem to be working ok.

trafficcritic

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Re: INRD bridge problem?
« Reply #11 on: August 29, 2019, 01:38:51 PM »
It's cheaper for the railroad companies to let nature take its course on these bridges and let them rot and fail catastrophically, possibly killing someone, than it is to proactively maintain them and keep them in good cosmetic condition.

It's only like this because the odds are in favor of the bridge not killing someone when it eventually does collapse.

NS7112

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Re: INRD bridge problem?
« Reply #12 on: August 29, 2019, 01:40:47 PM »
Facebook qualified Structural engineers aside, how'd you like it if a giant chunk of concrete fell on YOU or YOUR car?  Let's have some perspective here.  You'd be pretty pissed and want something to be done about it, right? 
SO, when the city says "hey, that's the railroad's problem..." People don't know how to contact the railroad, so they go to the news crews and facebooks...both of those sources just love a good scare story...and you see the shitshow that is created when that happens...

Agree!  Story isnít about the integrity of the bridge or whether or not it will collapse. Itís about the cosmetic look of how itís eroding and dropping dangerous chunks below. Reinforce it with some wire mesh that will catch the big chunks would be my quick fix. My guess is it wonít get thought about until something comes off it and goes through someoneís windshield and badly injures someone. Just the way our world works it seems!  Railroad is playing the odds game...

OrangeAndBlack

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Re: INRD bridge problem?
« Reply #13 on: August 29, 2019, 01:44:47 PM »
Facebook qualified Structural engineers aside, how'd you like it if a giant chunk of concrete fell on YOU or YOUR car?  Let's have some perspective here.  You'd be pretty pissed and want something to be done about it, right? 
SO, when the city says "hey, that's the railroad's problem..." People don't know how to contact the railroad, so they go to the news crews and facebooks...both of those sources just love a good scare story...and you see the shitshow that is created when that happens...

Yes. Thank you. Railroads arenít always in the right or wrong. If a bridge is dropping concrete, structurally sound or not, itís a problem.

Rick

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Re: INRD bridge problem?
« Reply #14 on: August 29, 2019, 04:25:08 PM »
Who actually owns the bridge?  Since itís old, Iím guessing the railroad paid for it.  I know around me, the newer bridges are city property according to the news articles that were published years ago when they were deciding who was paying for what.  Iím not sure how much is city property considering they received federal grant money as well. 


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crblue

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Re: INRD bridge problem?
« Reply #15 on: August 29, 2019, 05:57:11 PM »
As a point of clarification, the bridge in question is in Monroe County, not in any incorporated city or town.

IU_Tower

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Re: INRD bridge problem?
« Reply #16 on: August 31, 2019, 01:05:22 AM »
For some reason this Story will not Print out either. I have checked out my Printer and it seem to be working ok.

Sounds like your PEBKAC may be bad.....

trainmaster53

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Re: INRD bridge problem?
« Reply #17 on: August 31, 2019, 10:51:01 PM »
If this Bridge in Question, How many Railroad Bridges around the Country are in that state of Repair, and who is responsible for the repairs. The County Highway Department, City Street Department, or The Railroad in Question? Do we have to wait for something Bad to happen before we know that answer?

Rick

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Re: INRD bridge problem?
« Reply #18 on: September 01, 2019, 08:11:24 AM »
If this Bridge in Question, How many Railroad Bridges around the Country are in that state of Repair, and who is responsible for the repairs. The County Highway Department, City Street Department, or The Railroad in Question? Do we have to wait for something Bad to happen before we know that answer?
From my observations around Indiana and commuting through Chicago there more than a few bridges that are in need of repair.  I am not a civil engineer so I canít say how bad they are but many of the ones I think need repaired have quite a bit of steel exposed on the legs.  Some concrete is at least 4-6Ē think and itís missing in chunks.  Obviously these bridges need to be inspected annually Iíd think and apparently donít warrant immediate care. 


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BourdonBoy

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Re: INRD bridge problem?
« Reply #19 on: September 01, 2019, 08:17:46 AM »
Here's what the FRA expects:

https://www.law.cornell.edu/cfr/text/49/part-237

https://www.fra.dot.gov/eLib/details/L03212

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