The Morandi Bridge of Genoa was builted between 1963 and 1967 in a time where the amount of machines that passed every day was much lower than today, without blaming the usual mafia simply the Minister of Infrastructure said that there were only half a billion euros for ordinary maintenance when it would take at least 2, 5 billions! Also, in a few months should to start building alternative routes that would lighten the load on the bridge, but unfortunately the bridge has collapsed earlier.
Unfortunately it is a widespread problem in Italy where a lot of important infrastructures were built during the economic boom of the 50s and 60s and since then they have been subject to poor maintenance.