BOH wrote: ↑Tue Aug 04, 2020 08:37It was built in around 1 year as construction did not start until Summer 2019. It took a year for all the investigations and demolition following the collapse of the Ponte Morandi.
As I said above, the circumstances meant that they could avoid the many things that strangle construction projects in the UK, including consultation, as the route was already decided, the links to the road network already exist, the properties below were bought quickly to enable the remainder of the old bridge to be demolished for fear that gravity and the previous lack of maintenance would do the job for them, and there was no need to try and maintain existing traffic flows.
I can't think of a comparable example where a bridge of that scale has collapsed in the UK. Eastham Bridge near Tenbury Wells collapsed and was replaced within a couple of years, but it was a small stone arch bridge. The Cleddau Bridge collapsed while under construction, and was delayed by about 3 years, but the issue there was a look at the entire bridge design and technical approval process because of inherent problems with standards then applicable for box girder bridge design.
That said, I agree that all credit is due for rebuilding the bridge so quickly.
One of the first things we were told at university is that concrete is no good in tension but very strong in compression. Every time I look at the old bridge, I struggle with the fact that someone (or presumably several people) thought it would be a good idea to encase the main cables in concrete. Firstly, the extra dead weight the bridge would need to carry would be significant. Secondly, the dynamic loading on the bridge would cause the cables to stretch and contract a little, which would apply variable amounts of tension to the concrete. It seems inevitable that the concrete around the cables will crack and eventually break off. That concrete would be impossible to reach and repair, and it would make it very difficult to inspect the cables. When compared with the elegant cable-stayed Millau Viaduct, the Morandi Bridge looked far too heavy and clunky, and given that concrete is not suitable for use in tension, it just looked wrong.
I thought that was a given for all civil and building engineers?