The wasn´t any bridge in that area when they had the last earthquake in 1908.
Architects say the structure would be able to withstand an earthquake of more than 7.1 even if the epicentre were as close as 15km.
http://www.ingv.it/~wwwannali/dibona382.htm
I remembered that from 1990, the earthquake wasn't strong but very discouraging for engineers.