Why a Baltimore-type disaster is unlikely on the Confederation Bridge

As horrified people around the world watched the video showing the collapse of the Francis Scott Key Bridge in Baltimore, the thoughts of many turned to how safe the bridges they regularly cross are.

It took only seconds for the major Baltimore commuter bridge to accordion and collapse after one of its supporting piers was struck by the container ship MV Dali.

Officials from the operating company for the Confederation Bridge, which connects P.E.I. and New Brunswick, say the situation in the Northumberland Strait cannot really be compared to what happened in Baltimore.

"We are on completely different scenarios. The Baltimore harbour, the traffic in vessels, is just on a completely different scale," said Strait Crossing general manager Alexis Reynaud.

"Vessels this size are not allowed to travel anywhere near the bridge." 

Transport Canada regulations prohibit any cargo ship with a displacement (the weight of water a ship full of cargo pushes aside) of more than 47,000 tonnes from passing under the Confederation Bridge. For passenger ships, the limit is lower: 33,500 tonnes.

The displacement of the MV Dali was146,631 tonnes, more than three times the Confederation Bridge limit.

Transport Canada requires that any vessel with a displacement larger that 1,500 tonnes, a tiny fraction of the size of the Dali, have a local pilot on board when passing under the bridge. There is also a speed limit that is strictly imposed.

"There are guidelines and regulations in place but these are the main ones to guarantee we're not in the kind of situation where, unfortunately, Baltimore found themselves," said Reynaud.

The guidelines also say no vessel should pass under the Confederation Bridge in bad weather conditions.

Another significant difference between the Francis Scott Key Bridge and the Confederation Bridge is that the P.E.I. bridge was designed to stand against large floes of ice pushing through the Northumberland Strait and up against its piers.

In addition to the structure of the piers themselves, at water level they have sloped ice shields designed to deflect the impact.  

While a Baltimore-style disaster is unlikely, Transport Canada does have a contingency plan in place for an extended closure of the bridge.

That document is not public, though. Because it is the responsibility of the federal government, the P.E.I. government, a partner in those plans, will not discuss it. Transport Canada did not respond to requests from CBC News this week.