50 years ago it was quite acceptable to build a bridge that was fracture critical so that if one element failed, the whole bridge would come down, or at least a major portion. It’s possible those hole that were filled in were redundant fasteners and not needed then according to specs then. The holes would have needed to be filled in so as not to collect water and road salt. Either that or the contractors were cutting corners but wouldn’t it have been cheaper just to put the fasteners in instead of filling the holes?
At any rate when the 35W bridge went down in Minnesota, and later learned of the silver bridge in Ohio, I was amazed that back in 1960 they engineered bridges without redundancy. It just seemed to me to be common sense to provide back up for critical parts. (Just like a second jack under a car) For whatever reason it was the standard procedure back then, which is why there needs to be such a push to replace these 50 year old bridges. They were just poorly designed.
Yup!
Long before the bridge collapse in Minnesota, there was the failure/collapse of the Mianus River Bridge, which carried I-95, in Connecticut:
Preceding that collapse by ~ a decade, the legislature of the State of CT–in order to get through a financial crisis–enacted a statute that officially closed all state highways in CT, even though they remained open to traffic. I can recall seeing road signs in that state with incredibly small print that couldn’t possibly be read from a moving vehicle. Only by being stopped in a traffic jam was I finally able to read one of those signs, and found out that I was “proceeding at my own risk” by driving on that highway.
I can’t give you an exact timeframe, but my recollection is that it was in the late '70s that all CT state highways were “officially closed”, even though they remained open to traffic. Whether this allowed them to dodge lawsuits for vehicular damage, I have no idea. However, the fact that CT “deferred maintenance” on all of their roads and bridges for several years can probably be related to the collapse of the Mianus River Bridge.