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Published Nov 2024
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11 November, 2024: by Vanessa Pogorelic
You’ve got one minute. Find out exactly what you need to do as the clock starts ticking.
Vehicle submersions into water account for up to 10 per cent of all drownings in high-income countries such as Australia, Canada, New Zealand and the USA. Of all single-vehicle accident types, they have one of the highest fatality rates.
While the incidence of vehicles crashing directly into deep water is uncommon in Australia, floodwaters can also cause a car to become dangerously submerged.
In Australia, around 45 per cent of flood fatalities involve vehicles driving in floodwaters.
Between 2001 and 2017, approximately half of the deaths related to flooding in Australia were the result of victims being trapped in a vehicle.
In a fast-moving river or in flood waters, a four-wheel drive can lose stability and risk being washed away in just 30cm of water, and for small cars it can be as little as 15cm of water.
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Crash testing into water
Dr. Gordon Giesbrecht from the University of Manitoba in Canada is an internationally recognised expert in cold water immersion and has developed a protocol for escaping a vehicle in water.
His team has conducted extensive tests, submerging more than 90 vehicles in a controlled environment with passengers inside, to establish an exit strategy that gives occupants the best chance of surviving.
From the time a vehicle hits deep water, it may take two to four minutes for it to become completely submerged, that is, for water to cover the roof.
A car that has crashed into or been washed into deeper water will initially float then increasingly tilt forward due to the weight of the engine, which in most cars is in the front. As the car sinks, water will gradually rise, creating pressure on the doors.
Although instinct would lead most people to automatically try to open a door to escape, doors should never be opened once a car is in deeper water, as this would result in it sinking more quickly.
The immense hydrostatic pressure against the outside of the car will also make doors virtually impossible to open as the water rises.
There is also a misconception that waiting until water has filled the cabin and the pressure inside and out has equalised provides an opportunity to open the doors, however the air pocket left in a vehicle once it’s filled with water is not large enough to provide air to breathe. Any air pocket in the vehicle will also escape through the boot of the vehicle as it tilts further forward.
To have the best chance of surviving, you must escape through a window.
You have just one minute
According to Dr Giesbrecht’s research, you have about one minute to exit through the side window of a car before water starts reaching window level and prevents windows from being opened.
Here’s what you need to do as quickly as possible within that one minute:
Do not look for or even touch your mobile phone. It wastes time.
Unclip and remove your seatbelt.
Try to lower a front side window. In most vehicles, electric windows will continue to operate for 15 to 60 seconds.
If the driver or front passenger window can’t be opened, move to a rear seat. The rear of the vehicle will be higher in the water due to the forward tilt caused by engine weight.
Press your feet against a rear side window, placing your heels on the side of the window closest to the door hinges (towards the front of the vehicle) and punch hard until it breaks. A far more effective way to break the window is with a small tool designed to break auto glass. These can be purchased at automotive retailers and kept within easy reach inside a car. Most can also be used to cut seatbelts if they can’t be unclipped. Note: these tools cannot be used on front and most rear windscreens, which use laminated glass.
Once the window is broken, release children from seatbelts and child restraints. Children should be pushed through the window first, followed by adults.
Because of the short amount of time there is to safely exit the vehicle, most survivors of vehicle immersions save themselves. Even where bystanders call emergency services immediately, there is very little time to act where water is deep enough to completely cover a vehicle.
For this reason, Dr Giesbrecht emphasises that calls to emergency services by vehicle occupants should be avoided, and escape from the vehicle by the means described above should be given priority, unless the vehicle is only partially submerged.
The three phases of a sinking car
The period of time from when the vehicle first contacts water until it is completely submerged is referred to as ‘floatation time’. Floatation time is divided into three distinct phases: floatation phase, sinking phase and submersion phase.
The floatation phase occurs before the water reaches the bottom of the windows – this is the phase within which escape is most possible.
Once water rises higher than this, and until it reaches the roof of the car, the pressure on the outside of the vehicle makes doors almost impossible to open, and windows may also be more difficult to break from inside.
At submersion phase, all parts of the vehicle are underwater. At this phase, pressure inside and outside the vehicle is equalised.
Submerged vehicle safety now part of crash tests
In 2023, Australia’s vehicle crash testing program, ANCAP, added vehicle submergence to its safety assessments.
ANCAP CEO, Carla Hoorweg, says vehicle submergence safeguards added to vehicles will assist first responders to more easily gain access to those trapped inside during emergencies.
“In recent years, we’ve seen a number of significant flooding events across Australia. In addition to this, the number of new vehicle models fitted with electronic door opening mechanisms is also increasing.
“This highlights the strong need for better emergency access capability to help prevent unnecessary loss of lives.”
ANCAP’s vehicle submergence criteria require electric windows to function for up to two minutes after a vehicle becomes submerged, and that doors are able to be opened without battery power.
“In cases where side windows are not functional, manufacturers must offer a reliable method for occupants to break or open the windows."
Vehicles that allow easier escape for occupants as well as easier access for rescuers into the cabin once submerged will achieve a higher safety score. ANCAP also now requires information on the safeguards for submergence that are built into a vehicle, to be detailed in the owner’s manual.
Vehicle manufacturers are required to provide evidence that their vehicle’s doors and electric windows can operate under those conditions. ANCAP says in the absence of proof that side windows can still function for up to two minutes after submergence, the manufacturer must provide a method by which the vehicle occupant can open or break the side window to exit the vehicle.
This could be through the use of a tool to break windows or other mechanical means of forcing windows open.
Vehicle escape tools
Glass hammers and other similar tools, however, may not always be effective where laminated glass is used for side windows. Tempered glass breaks more easily and is designed to break into small shards. Some vehicles have laminated glass for side windows rather than tempered glass, or a combination of both.
Alex Forrest, RAC’s manager of Vehicles and Fuels, says there are both upsides and downsides to having vehicle side windows made of tempered glass.
“If it’s an emergency where someone needs to escape a vehicle or break into it to help someone get out, tempered glass is much better because it’s easier to break.
“But in a crash where there’s a risk of a passenger getting ejected from the vehicle, side windows made of more robust laminated glass may prevent that.
“Laminated glass is much more difficult to break due to the layer of vinyl between the two layers of glass that make up the laminated windscreen.”
You can easily identify the type of glass used in your vehicle’s side windows by checking the logo printed on the glass.
Tech and tools that can make it safer
While technology has made it more complex to escape a vehicle in water, more research and development is going into finding solutions, as the risk of vehicle drownings during flood events continues to increase globally.
Canadian company AWOS Technologies has developed a sensor-based system that will automatically lower electric windows on impact with water. The system can be fitted during vehicle manufacture or as an aftermarket device. AWOS says it is working with vehicle manufacturers to bring the device to market.
A compact glass hammer or a similar ‘car escape tool’ is a small investment motorists can make right now that could become a lifeline in an emergency. Just make sure you purchase one from a reputable supplier that can guarantee the quality of the tool, as not all glass hammers are effective.
In 2019, the American Automobile Association (AAA) conducted a series of tests with a variety of vehicle escape tools to determine how effective they were at cutting seatbelts and shattering glass in side windows.
Of the six tools tested, all were able to cut seat belts, however two required more effort, which took more time. When used to break tempered auto glass in vehicle side windows, two of the six tools failed to break the glass. AAA also found that spring-loaded glass breakers were more effective than the hammer-style.
Having a more effective means of escaping from a vehicle during any number of life-threatening emergencies is an essential aspect of vehicle safety, whether it’s to escape during flooding, bushfire or from a crash.
Knowing how to respond in these situations is also something motorists need to be better informed of.
While vehicle crashes into deep water are not common, they are a crash type few are prepared for, and very few know how to escape from.
