4 ms·

The 4 points in the article are all well detailed/explained, but he has a few parts that are either missing or represent theory much more than practice (on a si

by jaclaz 4y ago

The 4 points in the article are all well detailed/explained, but he has a few parts that are either missing or represent theory much more than practice (on a site titled practical engineering). >Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired . > Most construction projects are bid using a set of drawings and a book of specifications that include all the detail necessary to build them. An engineer, architect, or both has gone to great lengths to draw and specify exactly what a contractor should build, often to the tiniest details about products, testing, and procedures. You can see for yourself; just google your city or state, plus “standard specifications,” and scroll through what you find to get a sense of how detailed contract documents can be. We go to that level of detail in defining the project before construction so that it can be let for bidding with the confidence that an owner will end up with essentially the same product at the end of construction, no matter which contractor wins the job. This is pure theory/wishful thinking, the regulations/norms/specifications are a needed thing (and a good one), but projects in reality (non-trivial ones) are largely "vague" or however not detailed enough (there are exceptions, of course, but while the project does make an even enough bidding ground it usually fails to properly detail the construction). It is of course a compromise of sort, making a good project would simply cost too much and take too much time. The assumption here is that all the architects and/or engineers are omniscient, competent, honest and have all the time in the world to think about the project and an unlimited budget. >But, the lowest bidder model is still used around the world because it generally rewards efficient use of public funds. No, the lowest bidder model is still used around the world because it is the simplest way to assign a contract without (the public manager) being responsible of the decision to award it to company A instead of company B.

brudgers 4y ago
Experienced design teams know what the unknowns are. The same is true with experienced builders. And experienced owners. Hence everyone at their umpteenth rodeo knows that the low bidder has a list of change orders developed while preparing the bid. And everyone knows how the owner will react. And everyone knows how good or bad the plans are. Almost inevitably, the plans are good enough, which is all that's needed.
- jaclaz 4y ago
  There are usually three outcomes: 1) the builder changes are accepted at the same cost AND they are actually same or better than project 2) the builder changes are accepted at an extra cost AND they are actually same or better than project AND the construction goes over budget 3) the builder changes are not accepted, the project is (hopefully) executed as designed BUT the builder losing money will not complete it (or not complete it in time) with daily bickering on site AND an endless trail in Courts No, the plans - generally speaking - are not good enough.
  - brudgers 4y ago
    [ US standard practice based ] A change order always changes the cost of the work. “Change order” and “cost of the work” are terms defined in the contact (often by reference) and come with implementation protocols. Once a person has been around the block a few times, they usually realize that the plans are not the construction, the design brief is not what the owner actually wants, and the contractor doesn’t build everything right. And the whole thing is about working together to get the building built in a way that favors getting the next project.
    - jaclaz 4y ago
      >Once a person has been around the block a few times, they usually realize that the plans are not the construction, the design brief is not what the owner actually wants, and the contractor doesn’t build everything right. Exactly.
badpun 4y ago
> No, the lowest bidder model is still used around the world because it is the simplest way to assign a contract without (the public manager) being responsible of the decision to award it to company A instead of company B. You've made it sound as if it's about avoiding responsiblity, while the motivating force behind this model is to avoid creating situations which would incentivise corruption. When you take away any decision-making power from the official awarding the bid and he basically just has to follow a pre-written algorithm, he can't be corrupted.
- kqr 4y ago
  That might be the goal, but it's easy for even such an official to facilitate the process for individuals.
- jaclaz 4y ago
  Yes. I have made it sound like that because I wanted it to sound exactly like that. The "official" motivating force is the one you mentioned, but that doesn't mean that it is the actual one, nor that lowest bid is actually the best possible formula[0]. It is the up-to-date "the algorithm made me do it" version of the "officer, the devil made me do it" excuse when (if) the project is delayed or goes over budget, the builders are usually considered the culprits (whether it is actually their fault or not) and they were selected by applying the algorithm (so all is fine). Consider how you (private person) would normally award the construction of your house, likely you would: 1) find a list of local contractors (mostly from world of mouth) 2) get from 3-5 of them offers 3) compare them, analyze them with your arhitect/engineer, talk with offerers about possible mistakes/inconsistencies 4) finally choose the builder (more often than not you will choose not the lowest bidder but rather the one that overall seems to you more capable/reliable/interested in the work) With what a (say) local council would probably do to build (still say) a small school: 1) publish a request for bids 2) obtain anything between (say) 10 and 200 offers 3) award the contract to the lowest (and valid according to the algorithm) offer It is clear that in your private case you have no incentive for corruption, but - in order to avoid the risk of corruption - the council just awarded the contract to a "number". This "number", more likely than not, is the result of "blind shooting", the builders need a certain number of contracts and they need to make many offers, and have no time to analyze them in detail. [0] as a matter of fact "pure" lowest bid is relatively rare there are usually a number of corrective items either in the algorithm or in the norms regulating the bid, in some cases they can be effective, in some cases they introduce some perverse incentives to the offerers.
knorker 4y ago
>>Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? > Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired . Why does that time extension hold for the 50-year bridge but not the 25-year bridge?
- bumby 4y ago
  It does, but to a different probability of failure. A 25-year bridge extended to 35 years will have a higher probability of failing during that 10 year extension than a 50 year bridge extending life to 60 years. The most common survivability analysis is a Weibull model which typically has a longer right tail to the failure distribution.
  - knorker 4y ago
    The fair comparison is 25 extended to 30 vs 50 extended to 60, though. In terms of cost per year of having a bridge.
    - bumby 4y ago
      You’re right, I misinterpreted your point being about absolute age extension, not relative
- jaclaz 4y ago
  The point I was trying to make[0] is independent from the actual planned duration of the structure[1]. Of course it would apply also to the less lasting one. In a perfect world, besides ordinary maintenance (which rarely is performed anyway in a timely manner) when a bridge is near to its planned end of life (let's stay on the 50 year duration) it should be inspected and - if it is the case - its life could be extended by - say - 10% or 5 years, BUT there should already be present: 1) the projects and all authorizations for the new bridge 2) a reserve of money ready to be spent on the new bridge Then (and this is actually an increased cost/waste) these "granted" extensions of life could be repeated a number of times BUT should be "hard-capped" anyway to - say - 30% of the planned duration, in name of more certain safety, it will happen that you will demolish and rebuild a perfectly good bridge, but you will also in many cases prevent a disaster. What happens in the real world is that once the 50 years have passed, an inspection is made, and it is determined that everything is good enough, let's make another inspection in 5 years time or let's make this minor repair, and let's see what happens in 5 years time, rinse and repeat until the structure has double the planned lifetime and finally something happens (be it a structural failure, an accident, whatever) that forces to close the bridge (or to reduce load on it or in the worst case the bridge collapses) and at this point starts the race to make the project, get the authorizations, gather the money, etc, which adds two or three years to the time needed to have the new bridge built and usable. If you prefer, the issue I was trying to point out is that usually we need an "unexpected" event to trigger an "emergency response" whilst the bridge nearing its end of life is something known and expected. [0] which is that once something is built, for some reasons it is often considered (wrongly) to be eternal [1] which anyway is only a very rough estimate, not an exact number, duration for reinforced concrete or steel bridges depends on so many factors that is impossible to determine accurately a possible "structural" life.
deleted 4y ago
[deleted]
MichaelApproved 4y ago
> Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? > > Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired. Assuming the bridge would actually be replaced at its actual end of life (25/50 years) and assuming a horrible return on spending (double money for only double the life), I'd say the 25 year option would be better in many (not all) cases. From a cash flow perspective, it'd be helpful for a local government to avoid immediately spending on infrastructure costs that could be delayed for 25 years (when the lower cost bridge would be due to be rebuilt). From the unknown future perspective, the city/town population could possibly change (bigger/smaller) 25 years into the future. If the population grows, replacement bridge would need to be bigger and they could use the saved money to build a bigger one. Of course, if the population shrinks, they could spend less on a smaller replacement bridge. Again, this assumes a poor return on increased spending. Doubling the costs to double the life. If you could double the costs and triple the life or increase the cost by only 50% to double the life, the equation favors going with the longer term bridge.
- jaclaz 4y ago
  This is (good BTW) "pure financial theory". But the assumption here is that the replacement bridge is built "overnight" or however without altering in any way the normal traffic on and around it, which is very rarely the case, more likely you should expect months or years (of course depending on the size/complexity of the bridge) of limitations/difficulties with the city traffic, noise, dust and all the issues usually connected with construction sites. This is an indirect (hidden) cost of all kind of infrastructures that the population/users will have to bear.
  - MichaelApproved 4y ago
    Great points across the board. Thanks!
lowercased 4y ago
> >Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? > Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired . Was just relating this story to someone else the other day. As a kid, there was a lot of roadworks around us. Due to cold weather and hot summer, roads were constantly developing seams/buckles and potholes. This was often chalked up to 'unions bad - cheap materials - etc'. Newspapers would run 'investigations' every few years, etc. I think the road folks often did poor jobs of explaining decisions, and maybe it was literally always just "cheapest bid". But I look back at a road that was bad for years - it was repaved at least 3 x over a 10 year period I remember. THEN... it was expanded from 2 and 3 lane road to 6 lane. The land was there on both sides, and it had been in planning for probably 10+ years. Knowing the road will be torn up less than 10 years in the future, I can understand "just use cheapest patching for now" because it will get thrown away 3 years from now. However, that was never something that ever seemed to get across in news 'investigations'. Note, I'm going back to the 80s and 90s in my head, and I was younger - there may have been some info I missed, but even as I grew in to an adult... little hard info seemed to make it out to the general public.

by jaclaz 4y ago

brudgers 4y ago

Experienced design teams know what the unknowns are. The same is true with experienced builders. And experienced owners. Hence everyone at their umpteenth rodeo knows that the low bidder has a list of change orders developed while preparing the bid. And everyone knows how the owner will react. And everyone knows how good or bad the plans are. Almost inevitably, the plans are good enough, which is all that's needed.

jaclaz 4y ago
There are usually three outcomes: 1) the builder changes are accepted at the same cost AND they are actually same or better than project 2) the builder changes are accepted at an extra cost AND they are actually same or better than project AND the construction goes over budget 3) the builder changes are not accepted, the project is (hopefully) executed as designed BUT the builder losing money will not complete it (or not complete it in time) with daily bickering on site AND an endless trail in Courts No, the plans - generally speaking - are not good enough.
- brudgers 4y ago
  [ US standard practice based ] A change order always changes the cost of the work. “Change order” and “cost of the work” are terms defined in the contact (often by reference) and come with implementation protocols. Once a person has been around the block a few times, they usually realize that the plans are not the construction, the design brief is not what the owner actually wants, and the contractor doesn’t build everything right. And the whole thing is about working together to get the building built in a way that favors getting the next project.
  - jaclaz 4y ago
    >Once a person has been around the block a few times, they usually realize that the plans are not the construction, the design brief is not what the owner actually wants, and the contractor doesn’t build everything right. Exactly.

badpun 4y ago

> No, the lowest bidder model is still used around the world because it is the simplest way to assign a contract without (the public manager) being responsible of the decision to award it to company A instead of company B. You've made it sound as if it's about avoiding responsiblity, while the motivating force behind this model is to avoid creating situations which would incentivise corruption. When you take away any decision-making power from the official awarding the bid and he basically just has to follow a pre-written algorithm, he can't be corrupted.

kqr 4y ago
That might be the goal, but it's easy for even such an official to facilitate the process for individuals.
jaclaz 4y ago
Yes. I have made it sound like that because I wanted it to sound exactly like that. The "official" motivating force is the one you mentioned, but that doesn't mean that it is the actual one, nor that lowest bid is actually the best possible formula[0]. It is the up-to-date "the algorithm made me do it" version of the "officer, the devil made me do it" excuse when (if) the project is delayed or goes over budget, the builders are usually considered the culprits (whether it is actually their fault or not) and they were selected by applying the algorithm (so all is fine). Consider how you (private person) would normally award the construction of your house, likely you would: 1) find a list of local contractors (mostly from world of mouth) 2) get from 3-5 of them offers 3) compare them, analyze them with your arhitect/engineer, talk with offerers about possible mistakes/inconsistencies 4) finally choose the builder (more often than not you will choose not the lowest bidder but rather the one that overall seems to you more capable/reliable/interested in the work) With what a (say) local council would probably do to build (still say) a small school: 1) publish a request for bids 2) obtain anything between (say) 10 and 200 offers 3) award the contract to the lowest (and valid according to the algorithm) offer It is clear that in your private case you have no incentive for corruption, but - in order to avoid the risk of corruption - the council just awarded the contract to a "number". This "number", more likely than not, is the result of "blind shooting", the builders need a certain number of contracts and they need to make many offers, and have no time to analyze them in detail. [0] as a matter of fact "pure" lowest bid is relatively rare there are usually a number of corrective items either in the algorithm or in the norms regulating the bid, in some cases they can be effective, in some cases they introduce some perverse incentives to the offerers.

knorker 4y ago

bumby 4y ago
It does, but to a different probability of failure. A 25-year bridge extended to 35 years will have a higher probability of failing during that 10 year extension than a 50 year bridge extending life to 60 years. The most common survivability analysis is a Weibull model which typically has a longer right tail to the failure distribution.
- knorker 4y ago
  The fair comparison is 25 extended to 30 vs 50 extended to 60, though. In terms of cost per year of having a bridge.
  - bumby 4y ago
    You’re right, I misinterpreted your point being about absolute age extension, not relative
jaclaz 4y ago
The point I was trying to make[0] is independent from the actual planned duration of the structure[1]. Of course it would apply also to the less lasting one. In a perfect world, besides ordinary maintenance (which rarely is performed anyway in a timely manner) when a bridge is near to its planned end of life (let's stay on the 50 year duration) it should be inspected and - if it is the case - its life could be extended by - say - 10% or 5 years, BUT there should already be present: 1) the projects and all authorizations for the new bridge 2) a reserve of money ready to be spent on the new bridge Then (and this is actually an increased cost/waste) these "granted" extensions of life could be repeated a number of times BUT should be "hard-capped" anyway to - say - 30% of the planned duration, in name of more certain safety, it will happen that you will demolish and rebuild a perfectly good bridge, but you will also in many cases prevent a disaster. What happens in the real world is that once the 50 years have passed, an inspection is made, and it is determined that everything is good enough, let's make another inspection in 5 years time or let's make this minor repair, and let's see what happens in 5 years time, rinse and repeat until the structure has double the planned lifetime and finally something happens (be it a structural failure, an accident, whatever) that forces to close the bridge (or to reduce load on it or in the worst case the bridge collapses) and at this point starts the race to make the project, get the authorizations, gather the money, etc, which adds two or three years to the time needed to have the new bridge built and usable. If you prefer, the issue I was trying to point out is that usually we need an "unexpected" event to trigger an "emergency response" whilst the bridge nearing its end of life is something known and expected. [0] which is that once something is built, for some reasons it is often considered (wrongly) to be eternal [1] which anyway is only a very rough estimate, not an exact number, duration for reinforced concrete or steel bridges depends on so many factors that is impossible to determine accurately a possible "structural" life.

deleted 4y ago

[deleted]

MichaelApproved 4y ago

> Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? > > Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired. Assuming the bridge would actually be replaced at its actual end of life (25/50 years) and assuming a horrible return on spending (double money for only double the life), I'd say the 25 year option would be better in many (not all) cases. From a cash flow perspective, it'd be helpful for a local government to avoid immediately spending on infrastructure costs that could be delayed for 25 years (when the lower cost bridge would be due to be rebuilt). From the unknown future perspective, the city/town population could possibly change (bigger/smaller) 25 years into the future. If the population grows, replacement bridge would need to be bigger and they could use the saved money to build a bigger one. Of course, if the population shrinks, they could spend less on a smaller replacement bridge. Again, this assumes a poor return on increased spending. Doubling the costs to double the life. If you could double the costs and triple the life or increase the cost by only 50% to double the life, the equation favors going with the longer term bridge.

jaclaz 4y ago
This is (good BTW) "pure financial theory". But the assumption here is that the replacement bridge is built "overnight" or however without altering in any way the normal traffic on and around it, which is very rarely the case, more likely you should expect months or years (of course depending on the size/complexity of the bridge) of limitations/difficulties with the city traffic, noise, dust and all the issues usually connected with construction sites. This is an indirect (hidden) cost of all kind of infrastructures that the population/users will have to bear.
- MichaelApproved 4y ago
  Great points across the board. Thanks!

lowercased 4y ago

> >Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? > Of course the second (which is what is actually usually done) the issue being that in real world after 50/60/70/80 years the bridge won't be replaced/repaired . Was just relating this story to someone else the other day. As a kid, there was a lot of roadworks around us. Due to cold weather and hot summer, roads were constantly developing seams/buckles and potholes. This was often chalked up to 'unions bad - cheap materials - etc'. Newspapers would run 'investigations' every few years, etc. I think the road folks often did poor jobs of explaining decisions, and maybe it was literally always just "cheapest bid". But I look back at a road that was bad for years - it was repaved at least 3 x over a 10 year period I remember. THEN... it was expanded from 2 and 3 lane road to 6 lane. The land was there on both sides, and it had been in planning for probably 10+ years. Knowing the road will be torn up less than 10 years in the future, I can understand "just use cheapest patching for now" because it will get thrown away 3 years from now. However, that was never something that ever seemed to get across in news 'investigations'. Note, I'm going back to the 80s and 90s in my head, and I was younger - there may have been some info I missed, but even as I grew in to an adult... little hard info seemed to make it out to the general public.