Insurance broker Marsh has launched a $50m policy to cover the loss of revenue caused by port blockages similar to the container ship disaster in Baltimore.

The port of Baltimore was closed for 11 weeks after the 9,962-teu container ship Dali (built 2015) brought down the Francis Key Scott Bridge in March after suffering a loss of power.

The port closure contributed to the estimated $2bn to $4bn costs of the disaster, which also saw six construction workers killed who were working on the bridge at the time.