How to escape if your car goes underwater

A remaining section of the Francis Scott Key Bridge in Baltimore after it collapsed when a cargo ship hit a support structure. (Ricky Carioti/The Washington Post)

It’s a nightmare scenario for drivers: Your car leaves the road and plunges into water, transforming your vehicle into a sinking trap.

The collapse of the Francis Scott Key Bridge into the Patapsco River early Tuesday may have stoked fears that you could encounter a similar catastrophe in your own car. Officials with the Baltimore fire department said sonar has detected vehicles submerged in the water, but it was unclear whether anyone was inside.

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A distress call from the freighter that crashed into the bridge and caused the collapse gave officials time to halt more vehicle traffic over the bridge, said Maryland Gov. Wes Moore (D). As of midday Tuesday, two workers had been rescued from a crew that was repairing potholes on the Key Bridge; six workers were still missing.

In the right conditions, drivers who stay calm have a chance to escape an underwater car. In 2013, a 22-year-old woman from Calvert County, Md., survived after her car went off the side of the Chesapeake Bay Bridge and fell 27 feet into the water.

Thermal physiologist Gordon Giesbrecht, a retired University of Manitoba professor with an expertise in vehicle submersion and hypothermia, said passengers have one minute to rescue themselves from a sinking car. Once the vehicle becomes even partially submerged, the odds of survival are slim.

“A minute is kind of an average number,” Giesbrecht said. “So the windows will certainly work for 60 seconds, but if you know what you’re doing, you can open that window in 10 or 15 seconds.”

He said travelers should memorize the acronym SWOC:

-Seat belts off.

-Windows open.

-Out immediately.

-Children first.

“A lot of people think you should open the doors, which you shouldn’t,” Giesbrecht said. “The car is just going deeper and deeper, and once the water gets up against the window, then you won’t even be able to open the window. So you’ve got to get that window open as soon as you can.”

Giesbrecht said electric windows should still operate within a minute “because your ignition was on.”

When helping children, push the oldest out first so you can help the youngest passengers. Giesbrecht said it is easier to push than pull passengers out, so remain in the car until your dependents have safely evacuated.

Cars in deep water typically sink nose first, so you can buy a few more seconds by exiting out a back window. If there’s a release button in the front seat for a rear hatch, then you can escape through the back, but don’t waste time trying to locate it.

Once the car begins to sink nose down, the passengers will start to run out of air. Any air bubbles will escape out the back. In shallower water, a car might descend horizontally, so passengers could sustain themselves on a trapped air pocket, but Giesbrecht said this scenario is “very rare.”

According to Giesbrecht, smashing a car window is not feasible. Cars that have laminated windows instead of tempered glass are resistant to hard force; not one of the six tools tested in a AAA study were able to break through. A label on the bottom corner of a side window will identify tempered or laminated glass, but that helps only if you have it memorized.

Giesbrecht said that, when you have only a minute to save yourself, it’s not worth the time to search for an instrument.

“Very few people could ever break a window in the first place,” he said. “Once the physics of the water changes, you can’t break the window anyway, even if you had a hammer.”

Once you’re in the water, Giesbrecht said, you need to control your breath, assess your surroundings and climb onto or cling to the vehicle while it is afloat.

“You can hang on to the vehicle as long as you can,” he said, “or until you determine the closest or easiest place you can get to.”

Hypothermia is not an immediate problem, Giesbrecht said, because it takes an hour for someone to become cold enough for the heart to stop. However, drowning is a real concern, especially if you panic or go into shock after plunging into the water.

“The first thing that will happen when you’re in cold water is a cold shock response, which is gasping and hyperventilating or heavy breathing,” he said. The cold could incapacitate your muscles and nerves, and you could lose your ability to swim.

“We have the 1-10-1 principle,” Giesbrecht added. “You have one minute to get your breathing under control. Ten minutes of meaningful movement. And about an hour before you become unconscious due to hypothermia.”

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