Recent collapses raise questions on bridges and modern shipping.

Tuesday’s crash was at least the second in just over a month in which a container ship hit a major road bridge, raising questions about the safety standards of increasingly large ships and the ability of bridges around the world to withstand crashes.

On Feb. 22 in Guangzhou, a port in southern China, a much smaller vessel carrying stacks of containers hit the base of a two-lane bridge, causing vehicles to fall. Officials said that five people were killed.

The crashes have also raised questions about whether more ships should be required to be ready to drop anchors quickly during port emergencies, and whether tugboats should accompany more vessels as they enter and leave harbors.

There has not been a final report on the Guangzhou incident, and investigators have barely begun to look at what happened in Baltimore. But ship collision barriers are standard around the support piers of bridges over major waterways like the entrance to Baltimore’s harbor. The Verrazzano-Narrows Bridge in New York City, for example, has massive barriers of concrete and rocks around the bases of the piers that support it.

It was not immediately clear how old the barriers are around the piers that supported the bridge in Baltimore. The bridge was built almost half a century ago and designed before then. Vessels have become considerably larger in that time.

The crash in Guangzhou occurred on a less important waterway, a minor channel of the Pearl River. The bridge there was being fitted with devices designed to protect the piers in case of any ship crash. The work was supposed to have been completed by 2022 but had been delayed, and the latest target for completion was August of this year, according to China Central Television, the state