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The article I read about the bridge collapse says they have no idea why it did so. "Tax and spend" sounds fine to me, but spending can't substitute for figurin

by vba616 5y ago

The article I read about the bridge collapse says they have no idea why it did so. "Tax and spend" sounds fine to me, but spending can't substitute for figuring out what needs to be funded! If the bridge seemed fine, then first it needs to be determined just how anybody should've known it wasn't. Ignoring this is exactly the sort of thing that hardens people into thinking taxes are always wasted.

SAI_Peregrinus 5y ago
The bridge was listed as in "poor" (the worst of 3 possible conditions) and in need of immediate structural repair since 2011. There are pictures of rusted-through members, like this one[1] from 2018 where a diagonal member has been replaced with a cable and some prayer that it doesn't end up in compression. Google Street view shows the west side missing lower diagonal bracing[2] compared to the east side. The bridge was scheduled for fracture-critical and special inspections every 12 months. All 4 steel columns were at condition state 4 (poor condition, higher numbers are better condition).[3] We know why it collapsed, in general terms: it wasn't repaired for years. We don't know the exact trigger, there are so many bits that could have broken first it's hard to tell. It's quite possible the snow load, bus, and other vehicles were simply enough to overload it, since it had been derated from 67.5 tons down to 33 tons (26 tons on the sign in street view though). Those articulated buses used by PA DOT range from 19.5 to 22.5 tons curb weight, so the bus + snow load + 4 (or maybe more) other vehicles could easily have exceeded 26 tons. [1] https://res.cloudinary.com/engineering-com/image/upload/v1643378499/tips/Dvj4NduWsAAdPmz_pf1urs.jpg https://res.cloudinary.com/engineering-com/image/upload/v164... [2] https://www.google.com/maps/@40.4392955,-79.9003455,3a,75y,330.81h,91.9t/data=!3m6!1e1!3m4!1sAF1QipNHCy38zMhWSfrsfV9dkK9KrHGVcWitENDOZQ3b!2e10!7i5760!8i2880 https://www.google.com/maps/@40.4392955,-79.9003455,3a,75y,3... [3] https://infobridge.fhwa.dot.gov/Data/BridgeDetail/22435238#!#NBETab https://infobridge.fhwa.dot.gov/Data/BridgeDetail/22435238#!...
- vba616 5y ago
  I have no reason to doubt your facts, you sound knowledgeable, but there is something that you left out, that is important context. I knew to look for it because of the news article I previously read. It is this: "Substructure Condition Rating (60) 6 - Satisfactory Condition" I do not believe this was either the worst rated bridge or the highest priority, and surely there is nobody who deliberately let it happen, so there must be room for improvement in the management of PA bridges. PA has 3353 bridges in poor condition, according to reports.
  - SAI_Peregrinus 5y ago
    The substructure is the footings, essentially just the concrete bits in the ground, along with how well they're expected to work given the ground conditions.
    - vba616 5y ago
      I thank you for your useful links, but I feel like you're nitpicking or don't understand what I'm saying. The substructure was rated 6, and the superstructure and deck were rated 4, which is "poor". Yes. This document (https://www.fhwa.dot.gov/bridge/mtguide.pdf https://www.fhwa.dot.gov/bridge/mtguide.pdf) appears to define the ratings: "4 POOR CONDITION - advanced section loss, deterioration, spalling or scour. 3 SERIOUS CONDITION - loss of section, deterioration, spalling or scour have seriously affected primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present. 2 CRITICAL CONDITION - advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may have removed substructure support. Unless closely monitored it may be necessary to close the bridge until corrective action is taken. 1 "IMMINENT" FAILURE CONDITION - major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Bridge is closed to traffic but corrective action may put back in light service." If a bridge that collapsed was rated 4, and "imminent failure" is three grades below that, then I don't believe it's possible to avoid the conclusion that the process of rating and prioritizing maintenance has some flaw that needs correction. But I wasn't relying on the technical details that I didn't know in my original comment. I just was certain that the odds of all of the thousands of PA bridges being perfectly prioritized and this one being the precise bridge where funds ran out was essentially zero. There is, and will be, a lot of arguing about whether funds that should've been utilized for maintenance were diverted for political purposes. Something that has affected my thinking and made me more "squishy" as a Democrat is reading an article about how maybe the poor condition of the initial ACA website directly resulted from budgeting orders of magnitude too much money. Kind of like, choosing the wrong person to develop your website is one thing, but if say up front the budget is a billion dollars, nobody who's honest will even bid. As I said before, I still believe in "tax and spend" policy, but I am coming to think that overspending isn't just overspending, but also can ensure failure of itself. I don't want to read about the details of wasted spending in Iraq and Afghanistan, but I know in my gut what I'd expect.

by vba616 5y ago

SAI_Peregrinus 5y ago

The bridge was listed as in "poor" (the worst of 3 possible conditions) and in need of immediate structural repair since 2011. There are pictures of rusted-through members, like this one[1] from 2018 where a diagonal member has been replaced with a cable and some prayer that it doesn't end up in compression. Google Street view shows the west side missing lower diagonal bracing[2] compared to the east side. The bridge was scheduled for fracture-critical and special inspections every 12 months. All 4 steel columns were at condition state 4 (poor condition, higher numbers are better condition).[3] We know why it collapsed, in general terms: it wasn't repaired for years. We don't know the exact trigger, there are so many bits that could have broken first it's hard to tell. It's quite possible the snow load, bus, and other vehicles were simply enough to overload it, since it had been derated from 67.5 tons down to 33 tons (26 tons on the sign in street view though). Those articulated buses used by PA DOT range from 19.5 to 22.5 tons curb weight, so the bus + snow load + 4 (or maybe more) other vehicles could easily have exceeded 26 tons. [1] https://res.cloudinary.com/engineering-com/image/upload/v1643378499/tips/Dvj4NduWsAAdPmz_pf1urs.jpg https://res.cloudinary.com/engineering-com/image/upload/v164... [2] https://www.google.com/maps/@40.4392955,-79.9003455,3a,75y,330.81h,91.9t/data=!3m6!1e1!3m4!1sAF1QipNHCy38zMhWSfrsfV9dkK9KrHGVcWitENDOZQ3b!2e10!7i5760!8i2880 https://www.google.com/maps/@40.4392955,-79.9003455,3a,75y,3... [3] https://infobridge.fhwa.dot.gov/Data/BridgeDetail/22435238#!#NBETab https://infobridge.fhwa.dot.gov/Data/BridgeDetail/22435238#!...

vba616 5y ago
I have no reason to doubt your facts, you sound knowledgeable, but there is something that you left out, that is important context. I knew to look for it because of the news article I previously read. It is this: "Substructure Condition Rating (60) 6 - Satisfactory Condition" I do not believe this was either the worst rated bridge or the highest priority, and surely there is nobody who deliberately let it happen, so there must be room for improvement in the management of PA bridges. PA has 3353 bridges in poor condition, according to reports.
- SAI_Peregrinus 5y ago
  The substructure is the footings, essentially just the concrete bits in the ground, along with how well they're expected to work given the ground conditions.
  - vba616 5y ago
    I thank you for your useful links, but I feel like you're nitpicking or don't understand what I'm saying. The substructure was rated 6, and the superstructure and deck were rated 4, which is "poor". Yes. This document (https://www.fhwa.dot.gov/bridge/mtguide.pdf https://www.fhwa.dot.gov/bridge/mtguide.pdf) appears to define the ratings: "4 POOR CONDITION - advanced section loss, deterioration, spalling or scour. 3 SERIOUS CONDITION - loss of section, deterioration, spalling or scour have seriously affected primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present. 2 CRITICAL CONDITION - advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may have removed substructure support. Unless closely monitored it may be necessary to close the bridge until corrective action is taken. 1 "IMMINENT" FAILURE CONDITION - major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Bridge is closed to traffic but corrective action may put back in light service." If a bridge that collapsed was rated 4, and "imminent failure" is three grades below that, then I don't believe it's possible to avoid the conclusion that the process of rating and prioritizing maintenance has some flaw that needs correction. But I wasn't relying on the technical details that I didn't know in my original comment. I just was certain that the odds of all of the thousands of PA bridges being perfectly prioritized and this one being the precise bridge where funds ran out was essentially zero. There is, and will be, a lot of arguing about whether funds that should've been utilized for maintenance were diverted for political purposes. Something that has affected my thinking and made me more "squishy" as a Democrat is reading an article about how maybe the poor condition of the initial ACA website directly resulted from budgeting orders of magnitude too much money. Kind of like, choosing the wrong person to develop your website is one thing, but if say up front the budget is a billion dollars, nobody who's honest will even bid. As I said before, I still believe in "tax and spend" policy, but I am coming to think that overspending isn't just overspending, but also can ensure failure of itself. I don't want to read about the details of wasted spending in Iraq and Afghanistan, but I know in my gut what I'd expect.