In 1980, the Sunshine Skyway Bridge in Florida was struck by a ship and collapsed.

Since then, the construction of bridges has adapted – these days, engineers place large ‘dolphins’, or buffers, around the supports of any major bridge.

These concrete structures veer away from any ship that may run off course.

The disaster we have witnessed in Baltimore stems in part from the fact the Francis Scott Key Bridge was built in the early 1970s before this kind of technology was in place.

Therefore, the Dali container ship drove into one of the supporting legs of the bridge at 5 to 6 knots, imparting a force equivalent to many thousands of tonnes. It stood little chance against the impact.

And once a central support like that falls it is simply unavoidable that a bridge of that shape and length will collapse too.
There are around 300m between the bridge’s supports, offering a fairly wide channel for vessels. One question we are yet to answer is why the Dali had veered so far off its route.

In the case of Tuesday’s accident, there were some deflector devices in the water, but they don’t appear to be very large and were not sufficient to protect the bridge. The ship missed them and hit the bridge itself. What happened after that isn’t surprising.

When they come to design the new bridge, they may have to give it a wider span that would reduce the risk of a repeat in the future.

We regularly do simulations of vessel trajectories to analyse what path a vessel could take in a variety of scenarios.

Engineers might think to build spans of 500m or 600m, for example. They might also place the main, most load–bearing supports of the bridge in shallower water so any vessel runs aground before hitting them.

As cargo ships are also taller these days, they may want to increase the height of the bridge from around 55m to around 70m.

Economics will be a factor in the rebuild. There are British examples of cable–tied bridges that are both attractive and comparatively cheap, such as the QEII bridge in Dartford and the Mersey Gateway, which could be replicated over the Patapsco River.

With Baltimore still reeling from the disaster, the only relief for a stricken city is that it did not happen during rush hour.