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
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
- 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
- One problem is that driver's gain a false sense of security
(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
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.
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
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
Note that, for more than two decades, Australia has required
child restraints to have top tethers. In-depth accident studies show
that child restraints with top tethers perform exceptionally well in
severe crashes. Always attached the top tether to the approproate anchorage in the vehicle and tighten the tether.
The advice given here applies to Australia and is for
guidance only. Updated November 2009 to take into account new national laws. New national guidelines are being developed that will supersede the following advice.
My safety priority list for
children in a 5 seat vehicle (wherever possible
use the highest method in the list):