Switching to my day job persona for a moment:
Always check first whether you need a permit for something. Itâs easy enough.
And when you do need one, get one.
Who says modern architecture doesnât spark creativity.
This is insane.
Bridge collapse in Dresden:
No casualties.
Fucking hell. Itâs just a matter of coincidence that it happened at night and nobody was hurt.
According to the article it was built in the 70s and it was currently being renovated because the signs of fatigue were known. Now I wonder where else necessary repairs have been drawn out until it is too late.
Everywhere.
There was a massive surge of bridge building from the 1950ies to the 1970ies.
A lot of them are past their original design life. Nearly all of them have to deal with loads above their original design loads. More traffic, heavier vehicles, faster vehicles.
Anytime you see a bridge where not all of the lanes are in use (and itâs not because the surface is renewed), or have speed limits just for the length of the bridge, or odd weight limits (compared to the usual StVO Limits), or a combination of this - well, thatâs why.
Bridges are closely monitored. But there are a lot of bridges and only so many engineers to inspect them. Where feasible bridges are retrofitted with sensors. Newer structures have sensors built in during construction.
In some structures it is quite difficult to check the interesting bits. Like certain early constructions done in prestressed concrete. The load bearing tension bars/cables and their endpoints are encapsulated in concrete and not accessible. You want to think long and hard about probing those by drilling holes.
Fortunately you can do a lot now with x-rays and ultrasound, but that can be awkward and cumbersome. When you see weird scaffolding hanging off a bridge itâs often for some sort of inspection work.
Another problem is documentation. The original, certified and approved construction plans will only get you so far. You also need protocols of the on-site checks done by the testing engineers and the materials testing. Ideally there should also be the construction site managerâs diary and lots of photos from all phases of the construction.
Unfortunately, a lot of those have a tendency to get lost over the decades. The last resort are often old invoicing documents who seem to last longest in the archives.
If youâre lucky you can find some old geezer who was involved in the project and still has his own archive in his attic. Which usually also includes stuff nobody wanted filed in the official archives that turns out to be really useful.
The problem is slightly mitigated because structures like this are usually somewhat overengineered beyond the safety margins for practical reasons; rebar, steel girders and so on come in standard sizes and youâll always pick the larger one. And so on.
Also, bridges from the Cold War era were usually designed with military vehicles in mind. Especially the smaller ones tend to be a lot sturdier than meets the eye. Remember those little orange signs with cryptic markings? Those showed how many tanks and heavy loads the bridge could take.
One particular problem inherent in bridges in prestressed concrete is that they can fail without warning from one second to the next if one of the tendons breaks or its anchor fails. Like it happened with the Berlin concert hall. Happens quite often at night when thermal load adds to the tension. The tendon wants to contract just a little bit more but canât and snaps.
Which I think is what has happened in Dresden, but thatâs just an uninformed guess.
I was hoping for your professional opinion on the matters even if it isnât very reassuring. So this isnât necessarily neglect, but just the luck of the draw?
Not super cryptic, since they literally showed a picture of a tank! But, yeah, I do remember them and had them explained to me by my dad as a child.
Oh, it is neglect. Decades of neglect.
Infrastructure budgets (if there are any). Always to small for maintaining and replacing in time to begin with. Always mined for funds to stuff other holes here and there, pushing serious overhauls and replacements further down the line. Hey, this [insert structure] has been standing for [insert duration] - so itâs gonna stand for another [insert longer duration], right? Said the budget planner.
There is still this mental picture of âconcrete is foreverâ in far too many heads.
Granted, not entirely without justification given ancient Roman structures or WW II bunkers, but this is completely ignoring factors like a structureâs static system, types of construction, combination of materials, type of loads, environmental factors, and so on.
The problems are known and acted upon, but it is a calculated risk.
Just heard on the radio that
- it was scheduled to be replaced next year
- closely monitored
- they donât know yet what exactly happened, but corrosion was mentioned
