Africa Automotive News September-October digital issue 2019

Safety Tips
Caught up in a sinking car?
What to do
More common occurrences include being swept off the
road in a flash flood as a result of a natural disaster
The need to escape from a sinking
vehicle is a rarity. According to
available data less than one-half of
1% of all auto crashes involve submersion.
Yet, it does happen, and we need to
ask the question whether we would be
able to survive such an experience?
With enough know-how, survival is definitely
possible and we need to equip motorists
with information that will enable
them to survive. Motorists seldom have
to confront a bridge collapsing underneath
them and the risks are more often
associated with cars driving off quay-sides
or into rivers. Also included are problems
that arise when the parking brake isn’t
applied properly with cars simply rolling
down embankments into lakes or rivers.
More common occurrences include being
swept off the road in a flash flood as a
result of a natural disaster. It is important
to acknowledge that not all experts agree
on all the survival tips and the precise
sequence of escape – but there are some
common threads that need to be identified
and learnt from. On balance, it seems
that the best course of action is to try
and get out as soon as possible.
What to expect from a sinking
vehicle?
• The speed at which a car will sink
depends on several factors, including
the distance of the fall, speed
and angle of entry and the physical
characteristics of the vehicle.
• Most entries of vehicles into the
water are smooth entries with the
water cushioning the blow. Most
people survive the initial impact with
minimal or no injury at all.
• If you remain relatively calm there
should be enough time for you to
take action to save your life and the
lives of your passengers.
• Newer cars that are better at keeping
sound out will likely also be better at
keeping water out.
• Most vehicles will float for a minute
or two before beginning to sink. Cars
usually sink at an angle, with the
weight of the engine pulling down
the front first. A rear-engine car sinks
trunk-first.
• It is possible that the vehicle might
flip onto its roof in deeper water.
• In a test in a controlled environment
experts from the police tried to sink
a car and were surprised to find that
it took 5 minutes for the vehicle to
sink.
• In a car that sinks front first, there
will be a bubble of air in the back,
but you should stay in the front …
the front windows are often bigger
and easier to get out of — for all
passengers.
•
Vehicle sinking characteristics
An upright floating vehicle may take
2–4 min to completely submerge below
the water surface, however occupants
have only one minute (The Flotation
Phase) during which escape is possible.
During this period, water is rising against
the doors, preventing them from being
opened, however windows can still be
opened and occupants can exit through
them. After the first minute or so, the water
rises up against the windows exerting
enough pressure to prevent them from
being opened as well (Sinking Phase).
From this point on, although there is still
air in the passenger compartment, none
of the doors or windows can be opened
and the occupants are confined to death
through drowning.
Cars and pickup trucks are inherently
stable in the upright position because of
the mass and low position, of the motor.
Therefore, if passenger vehicles land in
the water upside down, and the windows
are closed and remain intact, the vehicles
will eventually right themselves by rolling
in the x axis. Likewise, vehicles landing
in water at a steep pitch (angled in the y
axis) will also eventually settle in the upright
position. Even at a steep pitch of up
to 60° or more, from horizontal, a vehicle
will penetrate the water and then bob
back up in the upright position and enter
the Flotation Phase. All of these factors
need to be considered in the design of
an AWOS.
Field tests
Prototype systems were installed on
two used cars at a gravel pit lake near
Winnipeg, Canada. All fluids were drained
from the vehicles and a crane was used
to place the vehicles in the lake either
by lowering them straight down into the
water (static tests) or by swinging the
vehicle into the water to produce forward
movement (dynamic tests).
Upright immersions: In both static
and dynamic tests, the windows opened
immediately and effectively when the vehicles
landed upright in the water. In each
case the windows were open before water
rose to the level of the windows and this
would have provided time for occupants
to exit before water flowed into the passenger
compartment.
Inverted immersions: One test vehicle
was statically lowered into the water in an
inverted position. The windows opened
quickly and the vehicle sank quickly while
remaining in the inverted position. In this
scenario, escape would have been unlikely
due to a combination of the short time
available and being in a disorientating
inverted position.
Basic Survival Tips
44 Africa Automotive News l 2019 September-October issue l 2019