Well, that dashes Governor Hockey Hair’s hope for the VP nod since the bridge failed on his watch after he said “no new taxes” and said the transportation department wasn’t important enough to have its own head.
(Transportation in Minnesota is screwed up - we spend a lot on roads and with the freezing and thawing that goes on around here, spend a lot more than states without wild weather swings. Then we compare ourselves to somewhere like Missouri and say “why do we spend so much on transportation?” Then we put through a transportation budget and our urban liberals want more money for mass transit if we have more money for roads, then the people from outstate start complaining about spending on roads they never use, the 'burbs just want more roads so they don’t need to sit in traffic…and then nothing gets funded adequately - this has been the state for 20 years).
I, for one, will never give up hope that he will get asked to be McCain’s running mate - I want to have a governor who really, REALLY knows the ins and outs of beer keg tossing (then I want a DFL governor, which would quickly follow a Molnau fill-in period).
In a word, no. Structural members are designed for the load they will carry. The design of each gusset plate is just a matter of sizing it so that it is thick enough to transmit the forces that the main members give it and big enough to hold enough bolts (or for older bridges, rivets) needed to transmit these forces. It could be 3/16" or 3/4" or whatever. The inspector has absolutely no way to know whether the thickness as designed is adequate. He could check the thickness vs the design plans or the shop plans but that doesn’t happen in normal inspections and in this case he would have seen that the thickness matches the plans.
The FHWA and the state DOTs take this very seriously. The FHWA has issued a Technical Advisory strongly advising the States to immediately inspect all steel deck truss bridges with fracture critical members. The DOTs certainly do not ignore such things and I am personally aware that my state has not only complied with the TA, we have gone well beyond what the FHWA has directed, as I’m sure the other states have as well.
The engineer who designed will make them the right size unless he made a mistake. To evaluate an existing plate, you need to load rate the entire bridge to get the forces in the individual members, then analyze the gussets with those forces. This takes time, trusses are a bit harder to model than your garden variety bridge. To answer the last question, this is an ongoing process but yes it will be done. The more immediate concern was to physically check all the plates for signs of distress which can be done very quickly.
Isn’t there a different method now also, BobLibDem? Back in the '60s we wouldn’t have used the LRFD method, for example. Or something like finite elements either.
Another thing I thought of: trusses such as the one in discussion aren’t used anymore. So, if you are thinking of ways to make the inspection process better, measuring gusset plates wouldn’t be on your list anyway.
Right. This was probably designed with Allowable Stress method, predating Load Factor and of course well before LRFD. You’re right that measuring gusset plate thickness is not high on the inspection improvement checklist. That sort of thing should be checked during construction or at the post construction inspection. In any event, the measurements would have shown the gussets were built as per plans.
I’d like to take that argument to another level. Most public infrastructure projects (design and construction) are awarded to the lowest bidder. Think about what that means in terms of engineering expertise or quality of construction materials.
ASCE rated US Infrastructure a D on its 2005 “Report Card.”
Engineers are not selected by a ‘bid’ process. Engineers are selected based upon qualifications.
Here’s how it works:
DOT has a project. They put out a description of what they need to have designed, along with a ‘call for proposals’. Each engineering firm puts together a proposal showcasing their expertise for the project - descriptions of the personnel teams including individual resumes. No cost is mentioned at this point.
The DOT then looks at all the proposals and makes a ‘short list’ of 4 or 5. These 4 or 5 firms meet with DOT - kind of like an interview. THEN the DOT selects the engineer. THEN the engineer puts together a cost estimate.
In other words, engineering expertise is not impacted by any bid process since we do not work that way.
Contractors are an entirely different matter. One caveat about that: the DOT reserves the right to reject any bid. If a company does not historically have the technical ability to build quality work, the DOT is likely to reject their bid. Our DOT has been very vigilant about that.
Honey, I’m the one who first mentioned that in this thread. Scroll up.
Oh, and the quality of materials is dictated by DOT standards. The DOT has a book of specifications which covers construction and material specs. Any material used on a DOT project must conform to those specifications. The material is tested according to a schedule as the project progresses.
In other words, the bid process cannot adversely affect the quality of materials either.
Right. The engineer will use a formula to determine the correct size plate. Why couldn’t the inspector use the same formula to double check the engineer? Perhaps the engineer could be required to “show his work” on the plans to make this easier.
There is obviously a process to determine what size gusset plate (or whatever replaced the gusset plate) to use. The engineers know how to make this calculation and do so when they make the design. Is there a particular reason why the inspectors could not also be taught this method so that they could catch mistakes made in the design phase?
He’d have to go to engineering school to learn the math & physics behind the methods. Some of those methods are computer programs, not simple formulas.
I assume you’re referring to DOT projects only. My field is water and wastewater treatment and I assure you, low bid is a large part of the selection process. (Processes vary, and some clients are better than other at mitigating the effects, etc.)
Good on the DOT for their bid rejection policy. Let me reiterate that this is not always the case when dealing with public projects. (Thus the popularity of Change Orders.)
I would amend your last sentence to “should not affect the quality of materials.”
There are some good and honest contractors out there, with whom it is a pleasure to do business. There are others who are not as sterling. The quality of materials is only as good as the submittal review (where a contractor often attempts to submit a lower cost material for the specified material) and depends a lot on the sharp eye of the field engineer (who notices that the actual supplier is a different supplier than the one listed on the submittal). Typically, your submittal review and field engineer are both tied to your design engineer. Further argument for hiring a good engineer in addition to a good contractor.
Allow me to congratulate you on your insightful observation!
Please note, I am not referring to Mississippi as I know nothing about their policies.
Many of our clients who have similar policies use contract restrictions limiting reimbursables and capping multipliers. The net effect is that the companies who would have been the low bidders are the only ones who can afford to pursue the contracts. The clients are still targeting the cheapest part of the market.
(Hopping the fence) To be fair, these rules were developed because clients were worried about being overcharged, which is a valid concern. However, the net result of these restrictions is a decrease in quality, since you usually get what you pay for.
I think they are using the term ‘mandated’ loosely; a look at this state-by-state matrixshows that all state projects are not necessarily covered under QBS law.
Barrett, you better watch your back if the APWA gets to pushing it.
Agreed. If these are municipalities or water associations, they need an advocate who will not only help them contract with quality construction outfits and oversee the work, but who will help them locate funding for the projects. Here that task usually falls to the city engineer - for the tiny towns that might be an outside firm or semi-retired individual rather than a staff member. I would think that quality of systems (such as electrical parts, SCADA systems, etc) would be of great concern in that type project.
