Take a walk in my shoes
3. Stopping distances
When using a road, you need to ensure that it is safe before you decide to
cross. Using a marked crossing (pedestrian/lights) is always the safest
option; however there will be times when you will need to cross a road
that does not have a designated crossing. Having an understanding about
stopping distances of vehicles will help you make a more informed decision
as to whether it is safe or not to cross the road.
The factors that influence the stopping distance of a vehicle are:
▸▸ Speed – generally, the faster a vehicle is travelling, the longer it will take
to stop. The formula for calculating speed is: distance divided by time.
▸▸ Reaction time – how long it takes the driver to react to a situation. If the
reaction time of a person is slower, they take longer to stop in a traffic
situation.
▸▸ Tyre tread – tyre tread affects how well a vehicle grips the road. Worn
tyres cause a vehicle to take longer to stop compared with a vehicle that
has tyres with a good tread. The more tread on the tyres, the shorter the
distance needed to stop.
▸▸ Surface – some surfaces are more slippery (e.g. a gravel road, wet road,
icy road) and stopping distances are increased on these types of surfaces
as there is less friction.
▸▸ Mass – the bigger the mass, the more momentum an object has.
Therefore, the bigger the vehicle, the more momentum that vehicle will
have when travelling on the road. A larger vehicle will take longer to stop
than a smaller one, even if all other things are the same. For example, a
bus or a truck will take longer to stop than a car or a motorbike.
10
Take a walk in my shoes
3. Stopping distances: continued
There are many factors which will determine when it is safe for you to cross.
Crossing at a marked crossing or where there are traffic lights is always the
safest choice. When you have to cross a road where there are no marked
crossings or traffic lights, list the things you would consider before making
the choice about whether it is safe for you to cross.
11