the driver's handbook

Speeding
and Inappropriate
Travel Speeds
50
Within South Australia the maximum default speed limit outside
a built-up area is 100km/h. The maximum default speed limit in a
built-up area is 50km/h. Unless a road sign or a licence condition
indicates otherwise, these are the maximum speeds at which
you are allowed to drive. Driving above the speed limit is illegal,
because it creates unacceptable safety risks.
Travel speed affects both the risk of a crash happening and the
severity of any injuries in a crash. Even small increases in vehicle
speed significantly impact on road safety risks.
Speeding can be compared to driving under the influence of
alcohol. Every 5km/h increase in speed in a 60km/h zone is equal
to an increase in 0.05 in BAC.
Speeding and inappropriate travel speeds are estimated to directly
contribute to at least 40% of deaths on South Australia’s roads
each year.
Also, speeds just 5km/h above average in urban areas and 10k/h
above average in rural areas are sufficient to double the risk of a
casualty crash.
Keep your speed down
For a fit and alert driver, in good driving conditions,
at 60 km/h it takes about ¾ of a second or 12
metres of travel for you to realise that you have to
brake and at least another 20 metres to stop. At
higher speeds, the distance will be even greater.
In good clear driving conditions, you must drive within the
posted speed limit however in certain circumstances, driving
at the speed limit for that road can be dangerous. Conditions such
as bad weather, heavy traffic, encountering children or pedestrians
may require you to reduce speed to suit those road conditions. If you
keep your speed down, you will have more time to avoid crashes
and will reduce the seriousness of any injuries or damage. You may
also save a life – possibly yours. You must only drive at a speed that
would allow you to stop your vehicle within the distance that you can
see ahead.
Keeping a safe following distance
The ‘following distance’ is the space between your vehicle and the
vehicle immediately in front. This distance varies, depending on the
speed you are travelling and the braking ability of both your vehicle
and the vehicle in front.
The acceptable minimum following distance, which is considered
reasonably safe, is the distance your vehicle will travel in three
seconds. This distance – about eight or nine car lengths at 60 km/h
– allows you time to glance at mirrors, signs, side roads and
vehicles further ahead while maintaining a sufficient safety
space should the vehicle ahead suddenly brake.
The Driver’s Handbook 13