Road Safety Tips
Over the last few years I have conducted investigations on
several road safety related subjects. There are a couple of
points about driving which stand out from this research. They
are raised here because they tend to have been over-looked by
road safety authorities in road safety campaigns.
A. VEHICLE SPEEDS AND PEDESTRIANS
See also Devices to help drivers control
their speed.
Updated 3 November 97, based on the paper "Vehicle Travel
Speeds and the Incidence of Fatal Pedestrian Crashes" by
Anderson, McLean, Farmer, Lee and Brooks, J. Acc Anal. and
Prev, Sept 1997.
- The chances of a fatal collision with a pedestrian are
linked to the speed of impact: At 20km/h 4% of collisions
are fatal. This rises to 9% at 30km/h, 25% at 40km/h 83% at
50km/h and, in effect, 100 % at 60km/h. Impact
speeds can also be related to equivalent drop height, onto a
hard surface: 20km/h=1.6m drop height, 40km/h = 6.3m drop
height, 60km/h = 14.2m drop height (that is, a drop from a
4th floor balcony) and 80km/h = 25.2m drop height.
- Vehicle frontal design has a slight influence but there
is no better countermeasure than reducing (or eliminating)
the speed of impact.
- In about half of all pedestrian accidents the motorist
has virtually no chance of braking or swerving - the speed
of impact is close to the initial speed of the vehicle (see
also the 1996 ESV paper by McFadden). In many cases there is
just no warning and the motorist would need X-ray vision to
be able to brake before an impact! In-depth investigations
into 103 child pedestrian accidents in Chicago indicated
that at least 72% involved "sudden appearance" of the
pedestrian where the driver was unable to take avoidance
action (Schofer et al, Accident Analysis and Prev, 1994)
- One problem is that driver's gain a false sense of
security because
(1) encountering a potential pedestrian collision is
(fortunately) an extremely rare event and
(2) the road environment (and caution shown by road users) has
generally evolved to cater for typical traffic speeds. These
typical traffic speeds are simply too high when the road
environment changes (for example, narrow streets with parked
cars) or when inexperienced vulnerable road users are about.
- VEHICLE SPEEDS SHOULD BE NO MORE THAN 40km/h WHERE THERE
IS A HIGH RISK OF A COLLISION WITH A PEDESTRIAN!
Particularly at school home times any motorist on the road
should expect to have to slow to no more 40km/h when child
pedestrians are about, such as outside schools or when
passing bus stops.
- NRMAs
comments about lower residential speed limits.
B. PARTIALLY RUNNING OFF THE ROAD AND OVER-CORRECTING
During a study of rollover crashes in
Australia I analysed dozens of fatal accident reports. A
recurring description in these reports was "ran off road then
over-corrected". In Australia many rural roads have unsealed
edges and there is usually a slight step up from the unsealed
edge to the sealed road surface. What appears to be happening
frequently is that a motorist (particularly an inexperienced
driver) accidentally lets the nearside wheels deviate onto the
unsealed edge of the road. They then panic and quickly turn the
steering wheel to return onto the sealed section. The problem is
that, as soon as the nearside front wheel returns to the tar,
the lateral (sideways) forces acting on the vehicle almost
double and the vehicle suddenly veers onto the wrong side of the
road (see animation). A
head-on collision or roll-over is a strong possibility. A
vehicle will travel quite safely, and will brake at a moderate
level in a controlled manner even if one side is on dirt and the
other is on tar - the wheels on the tar will keep you travelling
in a straight line. You don't need ABS brakes to slow down in
these circumstances, provided you don't brake so hard that the
wheels on the tar lock up.
IF YOU RUN OFF THE SIDE OF THE ROAD DON'T PANIC - GENTLY SLOW
THE VEHICLE DOWN AND RETURN TO THE TAR WHEN THE SPEED IS
LOWER.
C. ADJUSTABLE HEAD RESTRAINTS
As a guide, the top of the head restraint should be no lower
than eye level. This is slightly higher than the typical height
of the centre of gravity of the head and so the head restraint
should "catch" the head without causing severe rotation in the
event of a rear-end collision. Never leave the head restraint
pushed fully down. See the Insurance
Institute for Highway Safety site for a comprehensive
report on head restraints (Status Report).
D. CHILD RESTRAINTS IN AUSTRALIA
I recommend a "Type A2" dedicated baby capsule for infants
whose shoulders are not higher than the shoulder height
marker*(approx 12 months): e.g. Britax
B-Pod Go Baby Capsule
Then a "Type G" forward facing with full harness for
children whose shoulders are within the range of lower and
upper shoulder height markers* (approx 1 to 7 years): e.g. Britax
Maxi Guard Harnessed Seat
I also recommend avoiding convertible (converts from
rearward to forward facing) as they are an over-complicated
compromise. Also ignore the social media opinions out there
about the need to keep toddlers rearward facing. Australian
forward-facing child seats with harnesses and top tethers
provide have exceptional
protection for more than four decades
Australia. Top tethers are a very effective way to prevent
the child restraint and occupant tipping forward in a
frontal collision or tipping to the side in a lateral
collision, greatly reducing the risk of head impacts. In-depth
accident studies show that child restraints with top
tethers and six-point harnesses perform exceptionally well
in very severe crashes. Always attach the top tether to the
appropriate anchorage in the vehicle and tighten the tether.
* Important note (2011): The Australian Standard has been
revised to require shoulder
height markers on child restraints (see below). These
are a better indicator of correct fit than age, weight
or stature. Restraints complying with the new standard have
been available since 2013.
