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
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 March 2007.
My safety priority list for
children (wherever possible
use the highest method in the list):
- For infants up to 9kg in weight or 70cm in height - rearward facing infant capsule in rear seat
- For children up to 18kg in weight (around the 4th birthday for most children) - an approved child seat (with in-built harness) installed in a rear seat (preferably
the centre rear seat if top tether anchorage is
available)
- For children up 26kg in weight (around 8th birthday for most children) - an approved booster seat with a 3 point seat belt in the rear seat
- In Australia a booster seat
must NEVER be used with just a
2-point seat belt - some sled tests that Crashlab did in 1994 confirmed
the danger: the child dummy swung forward and down violently and its
head hit the floor!
Although the booster used in that test was very soft, compared with
modern designs, the compression of a typical seat cushion might result
in similar head excursion).
- A booster with side wings is recommended to support
the head of a sleeping child and to provide extra protection in side
impacts.
- Since the adult seat belt is taking the loads in a
frontal crash, exceeding the 26kg weight "limit" is not likely to be a
problem - see these RTA tips
for assessing whether a child is too big for a booster: "A booster seat
should be used until your child's shoulders no longer comfortably fit
within the booster seat or when their eye-level is higher than the back
of the top of the booster seat..." but see my notes about harnesses.
- Choose a booster that has a top tether strap that will hold it in place during a severe crash.
- For children who are too heavy for a booster seat, a 3-point adult seat belt in a rear seat.
- Where no 3-point seat belt is available in the rear seat, a 3-point adult seat belt in a front seat. A passenger
airbag will provide extra protection and
is not dangerous in Australia - provided the child is
restrained by the seat belt and does not lean forward. In any case,
adjust the seat as far back as possible but ensure that the sash
(upper) portion of the seat belt is against the shoulder and not the
neck. Never let a
child stand or sit close to the dashboard - airbag or no airbag.
- A 2-point (lap only) adult seat belt in the centre rear seat
Other points:
- A child is best protected in a forward facing child
seat with integral 6 point harness from when they reach 9kg or 70cm
tall (about 9 months) until they reach 18kg (around the 4th
birthday). This typically spans about three years and a three
year old will probably not want to be seen sitting in a "baby seat".
Buy a child restraint with this in mind and not because it can be
converted from infant capsule to forward facing child seat. Child Restraint Evaluation Program (CREP) tests
have generally found that child restraints designed for one purpose
(rearward facing or foward facing) perform best and they usually
accommodate a larger child.
- RTA advice "Choosing a restraint" - but it does not make the point that children should stay in a child
seat with integral harness for as long as possible. Although boosters
are "approved" for children as light as 14kg, children between 14kg and 18kg are safer in child seat. Channel 9 item - The Right Seat.
- Children should get priority over adults if there are not
enough seat belts to go around.
- Never have more than one person in a seat belt.
- Never carry a baby or child on your lap. In Australia
children under 12 months must always be restrained in an approved child
restraint (baby capsule or child seat).
- In NSW get tips on installing and using child restraints
from a Restraint Fitting Station - phone 1800 042865 or (61 2) 98305555. LIST OF RTA AUTHORISED RESTRAINT FITTING STATIONS Prepared by MOBILITY ENGINEERING
- If the car is fitted with side airbags in the rear seat
check with the manufacturer about fitting a child seat or baby capsule
to an outboard rear seat. In most cases a side airbag should offer
extra protection but in some cases it might not be appropriate to have
a child seat or capsule next to a side airbag.
- For commercial vehicles that only have front seats the
situation is less clear. The NSW RTA intended to carry out some
research on child seats and booster seats fitted to the front seats of
utilities with passenger airbags but so far the test have not been performed. It is expected that
children in forward facing child seats and booster seats
will be well protected when the airbag deploys. However, pending
the outcome of further research, infant capsules and rearward
facing child seats (convertibles) should not
be fitted to front
seats with airbags.
- In general, avoid child
harnesses that work in conjunction with a seat
belt. Even though these are Standards-approved they lack a method to
stop the lap portion of the seat belt from riding too high on the
child's abdomen. Crotch straps serve this purpose with the harness that
is built into a Standards-approved child seat. Some modern designs of
booster have an "anti-submarining clip" that is designed to work like a
crotch strap. If necessary, these can be used in combination with a separate child harness
in centre rear seats that only have a lap belt but make sure the
anti-submarining clip holds the lap belt in place. All Australian cars
should have a top tether anchorage in this position that can be used
for attaching the harness.
Australian Links
Overseas sites (might not be applicable to Australia)
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safety index
Publication Note
This page, and associated pages, are provided for guidance only. Please
check with local road safety experts for up-to-date information and
requirements in your area.
Last update - see News.
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