slow down...
keep your distance
Road safety initiative of Auburn City Council and Blacktown City Council.
RTA crash data for Sydney Region (2007-2009)
shows that
26 % of crashes are from the REAR END.
Almost half (42%)
of these crashes
result in injury
2007-2009 – 8796 INJURED
15 KILLED
Most of these crashes could
Have been avoided had the
3 SECOND GAP
been maintained !
To avoid a Rear End crash,
please take a couple of
minutes to read this important
road safety information…
You are driving down an average street…
…you see the brake lights of the car in front of
you suddenly came on…
You move your foot from the accelerator to the
brake to slow down your car…
BUT, there is a small time delay between the moment you
see the brake lights and when you foot touches the brake
pedal.
THIS IS YOUR REACTION TIME.
During that period of time, your car is still moving
at the same speed.
The faster you are going,
the further you will travel during this time
Q: HOW FAR DO YOU TRAVEL DURING REACTION TIME?
[reaction time 1.5 second]
YOUR
REACTION
TIME
includes:
A
How long the driver takes to
see the hazard, and the
brain takes to recognise it is
a hazard requiring an
immediate reaction
Can be as long as 0.25 - 0.5
seconds
B
How long the body
takes to move the foot
from the accelerator to
the brake pedal
Can vary from 0.25 –
0.75 seconds
Total reaction time can be as little as 0.75 seconds, but more realistically, the reaction time that is
used in calculations is 1 – 1.5 seconds. It is important to note that reaction time is a very complicated
topic affected by a large number of variables.
A reaction time of 3 – 4 seconds is likely if you are affected by tiredness, alcohol, fatigue etc.
Note that 4 seconds at 100 km/h means the car travels 110 metres before the brakes are applied.
The biggest factor in stopping distances is the speed at which
a driver reacts to seeing a hazard – DRIVER REACTION TIME
Response speed depends on several factors thus there is no single , universal reaction time value.
Factors that affect reaction time are:
EXPECTATION – when you are alert and expect things to happen you will respond quicker.
MENTAL LOAD – your reaction time becomes longer when there are a number of factors that compete
for your attention (eg. in car displays, mobile phones, passengers, thinking about work…).
NEW EXPERIENCES – your response to something you have never experienced before will be quite
slow (eg. Driving in Sydney CBD for the first time).
AGE – older people respond more slowly than younger people. However, older drivers generally
compensate for their slower reaction times with reduced speeds.
JUDGEMENT – a brake light, an obstacle in your path, a car coming towards you…It’s much more
difficult to judge the speed of something moving towards or away from you than something which cuts
across your path.
VISIBILITY – Reaction time increases as visibility decreases. It takes you longer to see and recognise
the hazard.
.
RESPONSE COMPLEXITY – more complex muscular responses take longer to perform.
TIME OF THE DAY – light level has little effect on your reaction time. It is the contrast between light
and dark shapes that makes it difficult to see hazards (eg. sunrise and sunset).
Once you actually get your foot onto the brake pedal
you will not stop immediately.
The total braking distance is made up of two stages:
BRAKING
DISTANCE
=
=
VEHICLE
REACTION
+
BRAKING
BRAKING TIME
Different cars have different braking distances:
Braking distances after reaction time on dry road, good tyres, good skills:
Depends on factors such as:
• The type of braking system in your car,
• Brake pad material,
BRAKING
DISTANCE
• Wheel alignment,
• Tyre pressure, tread and grip,
• Vehicle weight,
• Suspension system,
• The coefficient of friction of the road surface,
• Wind speed,
• Slope of road,
• Surface smoothness,
• The braking technique applied by the driver
• Weather conditions
As a general rule,
DOUBLING THE SPEED OF YOUR CAR
INCREASES YOUR BRAKING DISTANCE BY FOUR TIMES
Modern vehicle with good brakes and tyres, on a dry road doing 50 km/h, reaction time is 1.5 sec:
50 km/h
still doing 50 km/h
stopped
Inexperienced drivers are particularly prone to effectively 'freeze up’ at the sight of
an unexpected hazard.
That means their speed doesn’t change at all !
The following tables and graphs are for guidance only, as there are a lot of variables in real life situations.
Typical braking distance on a DRY SURFACE
A child runs onto the road 45 m ahead of you while you are travelling in 60 km/h zone. You brake hard.
WILL YOU STOP IN TIME ?
NOTE: Road is dry, you have a modern vehicle with good brakes and tyres. Reaction time used in calculations is 1.5 seconds.
Typical braking distance on a WET SURFACE
A child runs onto the road 45 m ahead of you while you are travelling in 60 km/h zone. You brake hard.
WILL YOU STOP IN TIME ?
NOTE: Road is wet, you have a modern vehicle with good brakes and tyres. Reaction time used in calculations is 1.5 seconds.
BRAKING
DISTANCE
COMPARISON
BETWEEN
WET AND DRY
SURFACE
This is a general
comparison only.
WHAT ELSE CAN HAPPEN ON A WET ROAD THAT AFFECTS
STOPPING DISTANCE?
RAIN
The car needs traction to move or to stop. Your tyres will
achieve the best traction on a clean and dry road. But the
road surface can be contaminated by dirt and spilled fluids from
vehicles. The first rain, after a long dry period, can be very
dangerous as dirt and water form a very slippery film and tyres
loose traction, as on icy surfaces.
After a reasonable amount of rain the dirt and slippery film will
be washed off the road surface.
Another danger on the wet road is:
AQUAPLANING
This is when the tyres progressively loose direct contact with
the road surface due to the layer of water that is wedged between
the wheel and the road.
The faster you go in wet weather the greater the chance your tyres
will aquaplane.
The function of the tyre’s tread is to remove water between the tyre and the road surface to
ensure better traction. As you increase speed on a wet surface, water is trapped by the tyre
as a wedge between the tyre and road surface. That trapped water builds up on the tyre
until the moment when the tyre separates from the road.
Example: At a speed of 80km/h a tyre must displace up to 25 litres of water per second
(a worn tyre will aquaplane sooner than a new tyre because it can’t get rid of as much
water).
SO, allow longer stopping distances and drive as smoothly as
possible.
To avoid aquaplaning, slow down in rain.
This tyre is
aquaplaning.
With better brakes in modern cars, vehicle stopping distances have
been reduced somewhat over the years.
But it should be remembered that no matter how good the brakes and
tyres are on your car, the road conditions still vary a great deal from
place to place. So,
DOUBLING YOUR SPEED INCREASES
BRAKING DISTANCE BY FOUR TIMES
Both your Reaction Time and your vehicle’s Braking Distance
vary according to
driver conditions, road and weather conditions
and vehicle conditions…
You need to recognise that :
No matter how good a driver you think you are
and how good your car is,
the difference between driving at the speed limit
and a few km/h over the limit
will result in a much longer stopping distance.
That could result in a crash.
The most common crash is a Rear End crash.
(26% of all crashes in the Sydney metropolitan area in 2007-2009)
To avoid a rear end crash you should maintain a
3 SECOND GAP
between your vehicle and the vehicle in front of you.
WHY a “3 second gap” ? Why not use car lengths?
The old myth that suggested counting car lengths between vehicles
at certain speeds is very inaccurate as people are unable to judge
car lengths accurately.
What is the 3 SECOND GAP ?
Simply select a
stationary marker point.
When the vehicle in
front of you passes that
point start counting:
“one thousand and one,
one thousand and two,
one thousand and three”
Always use a stationary object as the marker (never a moving one). Your stationary marker point
can be anything on or near the road such as sign posts, light poles, painted markings, reflective
lights, pot holes or patches, shadows, parked cars etc
…If you reach the
stationary marker
point before you
count to
“one thousand
and three”
you are following
too close
(on a dry road).
Slow down and
drop further back.
As soon as the surface gets wet, or even just damp, three seconds becomes inadequate as a following
distance! Use at least a 4-second gap on a wet road and 10 seconds on icy roads.
When the road is icy, covered with compacted snow, or fuel has been spilled
the 'braking distance' for your vehicle can be as much as ten times further than for dry roads.
Remember that the ‘first rain’ is as dangerous as ice on the road !
Example:
Practical
example of
stationary
marker:
“cats eye”
Just focus on the one
of your choice… count
1 -1000
2 - 1000
3 - 1000
You should now pass
that point
WHAT IS THE 3 SEC GAP?
WHY NOT CAR LENGTHS OR METRES?
WHY SECONDS?
DISTANCE
SPEED =
TIME
[
km
h
DISTANCE = SPEED x TIME
[m] =
20 =
40 =
60 =
[m/sec] x [sec]
20 x 1
20 x 2
20 x 3
[20 m/s = 72 kph ]
m
=
s
]
Counting time means your
distance changes with your
speed, always giving you the right
3 seconds of following distance.
Note: the gap should be
increased from 3 sec according to
the conditions (driver, road,
weather and vehicle conditions).
WHY 3 seconds?
THE KEY ISSUE...
The key issue is understanding
what is simultaneously happening
with driver’s reaction, speed and distance.
1
second
reaction
speed
distance
Crashes occur in milliseconds and seconds…
If speed is expressed in metres per second, it’s easier to get a feel of
it…eg. 80 km/h is the speed of 22.2 m/s…
that means the vehicle will pass 22.2m every single second !
If a vehicle is moving at 80km/h and an average driver’s reaction time
is 1.5 seconds the vehicle will pass 33 metres without any speed
reduction …as the driver is still reacting !
}
speed
km/h=m/s
1 sec
1.5 sec
2 sec
3 sec
60=16.7
17
25
33
50
80=22.2
22
33
45
67
110=30.6
31
46
61
92
<
}
driver’s reaction time
distances
Position for safety
You are driving the red car.
You can’t see what’s in front of the blue car if you are too close!
basics for safety
Position
<
Increase the distance and
you are positioned for safety!
You’ll have enough time and
space to stop in emergency.
<
2 second following distance
1 second following distance
Position for safety
<
A very common following distance
on our motorways…eg:
Speed = 100 km/h ( 27.8 m/s)
Reaction time = 1.5 second
Actual distance = 15 m
If driver 1 has to react suddenly they
need 41.7 m just to react. They only
have 15 m available!
DRY
Reaction distance = 41.7 m
Braking distance = 49.2 m
Stopping distance = 90.8 m
WET
Reaction distance = 41.7 m
Braking distance =
65.6 m
Stopping distance = 107.2 m
2.
1.
MYTH:
I will save travelling time if I drive close – this stops other cars cutting in on me.
Our team conducted a survey of drivers and discovered:

67% thought they were keeping a safe distance by judging the following
distance either by car lengths or in metres,

60% had heard about the 3 second gap but only 44% knew how to apply it,

Alarmingly, only 22% of drivers actually use a 2 or 3 sec gap while driving.
In order to bust this myth we conducted an experiment (similar to the US).

2 cars drove from Auburn to the Sydney CBD and back - a total of 35 km at
approximately 2:00 pm on a mid week day. Both cars obeyed all the road rules. Traffic
varied from medium to heavy. 90% of the journey was done on the M4 and Parramatta
Road.
Results:

The driver of Car A used a proper 3 second following distance all the times.

The driver of Car B varied their following distance from approximately 0.5
to 1.5 seconds.

The total advantage in travelling time for Car B was 6 seconds.
TRY THIS
If another driver cuts in front of you,
restart your count on their vehicle and drop back once more.
It may test your patience, but it's better than being injured because you
were simply driving too close and couldn't stop.
And you have lost only a couple of seconds that you will regain when
you stop at the next traffic lights.
A US experiment has shown that driving from Philadelphia to New
York City, a 160 km trip, using a 2-second rule added a total of two
minutes to the drive time.
They also found that if a 3-second rule is used, instead of a 2
second rule you’ll reduce your crash risk by a further 70 percent.
Consider this: "The vehicle ahead stops suddenly"…
If you run into the back of the vehicle it simply means:
 you weren't paying enough attention
or
 you didn't leave a big enough gap between the vehicles
or
 you were driving too fast for the conditions
or a combination of these.
And the Police will say the crash was your fault – so you pay for
the damage.
BE PREPARED
KEEP THE 3 SECOND GAP.
What if you are being tailgated?
Keep in mind that when someone is tailgating you ,
you have to add their following distance to yours,
so if you have to react you’ve got the extra time and space
to slow or stop without the tailgater hitting you.
To get them “off your back” simply pull over and let them pass !
DRIVE SMART !
SAFE DRIVING TIPS
 Watch a couple of cars ahead of you (not just the one right in front)
 Scan the road for possible hazards
 Anticipate others reaction and be ready to react
 Maintain at least a 3 sec gap (appropriate for the conditions)
Auburn & Blacktown
City Councils
ENCOURAGE SAFE
DRIVING
Road safety initiative of Auburn City Council and Blacktown City Council.
August 2011