Following Margins.
Following distance
The driver who runs into the vehicle ahead in most cases will be in the wrong and
will often be liable to prosecution for negligent driving. You must bear in mind
that a certain time (driver reaction time) will be required between seeing a danger
signal and taking evasive action. This time varies considerably but the average
is at least one second and could extend to several seconds if concentration has
lapsed. A vehicle travelling at 60km/h covers 16.7 metres per second. If your following
distance is 17 metres or less and the driver ahead brakes severely, you will collide
with him before you have time to apply the brake.
The driver should leave an interval of TWO SECONDS between your vehicle and the
rear of the vehicle in front. Two seconds can be fairly accurately measured by saying
the words "one thousand and one, one thousand and two" at normal speaking speed.
When the rear of the vehicle ahead passes some marker, say, a shadow on the road
or a lamp post, begin to say these words. If your vehicle has passed the selected
point before the words have been completed, your following distance is insufficient.
This method allows for different speeds.
What to do when driver behind is following too closely. In this case, a sensible
precaution is to increase following distance from the vehicle ahead so that if the
driver ahead brakes heavily, you can slow down relatively gently. Moving to the
another lane or increase your speed or slow your speed down to encourage the following
vehicle to overtake are other strategies to consider, depending on the circumstances.
The space cushion
By modifying your positioning on the road relevant to the location of other vehicles
will avoid you having to modify your driving to the whim of other drivers. The "space-cushion"
is the elbow-room around your vehicle, you should adopt a position as far away from
the other road users as conditions will allow. In dense or congested traffic this
spacing will be limited, but elsewhere it should be exploited to advantage.
When driving side-by-side with a vehicle in an adjacent lane, that vehicle may weave
or cut across, in which case you will be forced to take sudden evasive action. Again,
if another vehicle, particularly a small car, remains in your blind spot for any
length of time, you may forget it is there when you want to change lanes. This situation
can also be reversed. Maintaining a space-cushion will prevent all of these unpleasant
and risky situations, and allow the driver a much safer and more relaxing journey.