The big container ships that ply the world’s trade routes are growing ever larger, holding down the cost of ocean shipping, but also raising concerns among vessel operators, insurers and regulators about the potential for catastrophic accidents. The ships, designed to carry freight stowed in large metal containers, transport much of the world’s seaborne cargo, including manufactured goods and, increasingly, farm products. Their increasing size already is straining the unloading resources at some port facilities and—along with labor troubles—has contributed to major traffic snarls at the nation’s West Coast ports. Since the economic downturn, shipping lines have sought to stay competitive by running larger, more fuel-efficient container ships in major shipping […]