Three ships have hit bridges in different countries -- in just three months. Should we be worried?

A deadly bridge collapse in Baltimore. A bridge in southern China sliced in half. Parts of a bridge cutting through the hull of a massive ship in Argentina. These events all happened within the first three months of this year – and all after collisions with large commercial ships. These incidents, and the toll – with at least five killed in China, and six still missing in Baltimore – have highlighted what experts say is the urgent need to improve or protect old bridges to accom