Jacksonville residents have been assured by the mayor that the Dames Point Bridge is protected against accidents such as the one that took place in the Port of Baltimore this week.

It was fortunate that a “mayday” signal enabled authorities to shut off traffic on the Francis Scott Key Bridge in Baltimore, preventing cars from plummeting into the freezing waters. Six workmen on the bridge were killed of eight who fell in the water.

Mayor Donna Deegan said in a press release, “Undoubtedly, people are wondering about the safeguards in place to protect our infrastructure here in Jacksonville. The Dames Point Bridge, the only bridge that cargo ships calling JAXPORT sail under, has hard infrastructure (large concrete structures called “dolphins”) in place to protect the base of the bridge piers from any vessel impacts. Additionally, specialty sensors (called Air Gap sensors) are located on the bridge to provide real-time information on the distance between the water surface and the bottom of the bridge structure over the main channel.”

There is a reason the piers holding up the Dames Point Bridge are protected by dolphins, designed to deflect ships that are off course in the St. Johns River.

There was a heated political fight in the 1970s over building the Dames Point Bridge. Among other tactics – such as labeling it the “bridge to nowhere” — opponents said that ships would hit the bridge and bring it down.

That was rather insulting to the St. Johns River bar pilots, whose job it is to guide ships under the bridge, but nevertheless it was answered by building the dolphins.

However, another bridge in the city may be more vulnerable.

On a list of “at risk” bridges that lack safety features is the Hart Bridge in downtown Jacksonville. It was built in 1967, 10 years before the Baltimore bridge, to bring traffic from Southside into downtown near the Gator Bowl.

Deegan noted, however, that cargo ships that sail under the Dames Point Bridge do not pass under the Hart Bridge, which is farther upstream.

The Key bridge had safety devices added after the Sunshine Skyway disaster in Florida in 1980, when cars were hurled into the river as the bridge collapsed.

Dolphins are not complete protection against the mass of a drifting ship but can help. Engineers say only building ground around bridge piers so that a ship would go aground before hitting them is adequate protection. The Sidney Lanier Bridge in Brunswick has such a feature. That bridge was built in 2003 – using the same design as the Dames Point Bridge — to replace an earlier one that fell in 1972, killing 10 people, after being hit by a ship.

According to the Associated Press there were 35 major bridge collapses worldwide resulting from a ship or barge collision from 1960 to 2015 with 18 occurring in the United States.