June 2015 | LTrent

Speed and Speed Limits

Speed is the biggest single danger on NSW roads, contributing to about 40 percent of road fatalities each year.
The setting of speed limits plays an important part of efforts to reduce this statistic.
To stay safe on the road, it is important to understand:
• What is a speed limit
• Why there are different speed limits
• Why different speed limits are applied in different areas
What is a speed limit?
Speed limits indicate the maximum safe and, therefore, legal speed for vehicles under ideal conditions.
A speed limit is the maximum speed you are allowed to travel in a sign posted area but
Drivers should reduce their speed as road and weather conditions dictate.
Many drivers will see a speed limit sign, say 80km/h and drive at this speed regardless of the traffic or weather situation. If it’s rainy, dark and busy, driving at 65km/h may be a better idea.
There are three types of speed limits used in NSW:
Default speed limits
Signposted speed limits
Special speed limits based on vehicle and licence class
Default speed limits – 50 km/h in built-up areas and 100 km/h in non-built-up areas. These speed limits apply to roads in the absence of sign-posted speed limits.
Common speed limits in NSW:

School Zone Built-up Area Rural Area Highest Speed Limit
40 50100110

Why are there different speed limits?
There are number factors that determine the speed limit in any given area.
These include pedestrian activity, traffic controls and hazards.
The most important factor about speed limits is they take account of stopping distances in relation to the conditions that may be around.

Stopping Distances
It is important to know that different speeds have different stopping distances:

40 11.117 m8 m25 m
50 13.921 m13 m34 m
60 16.725 m18 m43 m
70 19.429 m25 m54 m
80 22.233 m32 m65 m
90 25.038 m40 m78 m
100 27.842 m49 m91 m
110 30.646 m60 m106 m

When driving we need to allow enough space between ourselves and other road users. We need to allow time to react and to brake.
A general rule is to allow 1.5 seconds for each making three seconds the minimum space needed between vehicles.

40 km/h
40km zones are usually found in areas with a high number of pedestrians such as school zones, road works, bus stops and high pedestrian activity areas.
With pedestrians about drivers will need to be able to stop the car very quickly should someone step out in front of the car.
At 40km/h, it will take on average thirteen meters to stop your vehicle. You also need to allow seventeen meters of reaction time.
You will need a total of 30 metres of space to stop your car at 40km/h.
School zones – in NSW school zones are usually operating 8:00am to 9:30am and 2:30pm to 4:00pm. However, some schools have different times so always check the signs. As well as being marked by signs, school zones are preceded by dragons teeth painted on the road surface.
Roadworks – will have temporary signage and may have a high number of people very close to the roads edge.
Bus stops – when buses are dropping off passengers and leaving the kerb, there will be flashing lights either side of the 40 sign on the back, meaning drivers cannot pass the bus at more than 40km/h. Many learners fail their driving test for passing a bus at more than 40km/h with the flashing lights on.
High pedestrian activity areas – more and more of these are being implemented and are found around shopping centres, train stations and busy high streets.
50 km/h
50km/h is the most common speed limit. This is the default speed limit for built-up areas in NSW and is found in built-up areas and on most suburban streets.
There will still be a high chance that you will encounter pedestrians in these areas along with frequent intersections and hazards.
Being the default speed limit, it is rarely signposted.
50km/h zone’s are vitally important for learner drivers sitting a driving test. If you can’t see any speed signs, then assume it’s a 50 km/h zone.
80 km/h
This speed zone is usually found on divided roads without driveway access in urban areas, undivided arterial roads on the fringes of urban areas and lower quality rural roads. These roads have significantly fewer hazards and pedestrians than lower speed zones, allowing safe driving at a higher speed.
The difference in stopping distance between 40 km/h and 80 km/h is significant.
80 km/h is double the speed but requires quadruple the braking distance.
100 km/h
This is default speed limit for non-built-up areas in NSW. Roads with this speed limit include divided rural roads, higher quality undivided rural roads and urban motorways. These roads will be free from most hazards.
Stopping distance at 100km/h is over 90 metres.
110 km/h
This is the highest speed limit in NSW. 110 km/h zones will only be found on high quality rural divided roads and non-urban motorways and freeways. These roads are free from most hazards found at lower speed zones. Curves in the road will be less pronounced, and vision will be good.
The more space and vision we have, the safer it is to drive at higher speeds. Crashes at speeds between 80 and 110 high a far higher risk of ending as a fatality.