I would agree with the understanding that when the number of simultaneous strikes are limited, then it becomes less likely that a bridge or tunnel is a target. But with many strategic targets on the line what would be the impact on our economy if a bridge spanning the Mississippi River could be dropped thus blocking the passage of river traffic in either direction? Think of an attack on the Golden Gate Bridge. Right here in Miami, dropping a bridge (even a small bridge) across the Miami River would put a choke hold on trade with many carribean countries. Don't think of bridges or tunnels with no significance other than traffic convience, think of targets with wide ranging impact if destroyed.
I understand, and would agree especially within the context of a more conventional conflict. However, jihadists (except for Iraq) have consistently chosen greater casualities over infrastructure/strictly economic attacks. Greater terror potential when more people get killed.
Or a locks and dam. The McAlpine locks and dam on the Ohio river will be closed in a few weeks for repairs. Companies that use the river are doubling up on their shipments, but expect the impact to be devastating.