Right Turn Drive Line.
Negotiating corners with smoothness requires an understanding of where to position
your vehicle prior to a turn or corner. The force on a vehicle executing a turn
is called centrifugal force, this force tends to cause the vehicle to want to go
straight ahead. The aim of the driver is to reduce the forces on the vehicle, this
can be achieved in two ways, reducing the speed of the vehicle and increasing the
radius of the turn.
Inexperienced drivers and those with a lack of training often follow the advice
"straighten a curve" this advice can be misleading encouraging the usual tendency
of cutting in too early, resulting in a familiar sight of the vehicle weaving from
the exit of the turn.
In a right-hand curve, for example, the driver starts well to the left, moves progressively
to the centre-line coming nearest and a little past the middle of the curve and
leaves the curve well to the left again, thereby having eased the cornering line
particularly towards the exit and so requiring less steering rotation.
There are four terms you will need to know, they are the APPROACH, ENTRY, APEX,
EXIT, these terms are the sighting or target points of the corner. The assessment
will focus on your ability to position your vehicle effectively for the turn, knowing
how to sight the rotation point or entry point will help to avoid the vehicle entering
the corner to early and the deduction of points during your licence test.
Your "approach" position will wary depending on whether you are intending to turn
left or right, the approach position for the left turn should be some way off the
left kerb say 1.5 to 2 metres. For the right turn your vehicle should be positioned
to the left of the centre of the road, within say 1 metres.
The "entry" is the point where the rotation of the steering wheel is initiated for
the turn, you should be able to see the "driver apex" clearly at this moment. On
an extended curve taken at moderate speed, there should be no need to move the wheel
at all after the initial turn, assuming that the curve is of constant radius.
The "driver apex" is the point the vehicle should be closest to in the turn, for
the left turn you should clip this point about half a metre from the kerb or shoulder.
The "exit" is the point where you should have completed the turn and the front wheels
are returned to the straight ahead position. The "exit" is the last target point
of the turn, for the left turn some way of the kerb, say one to two metres. By sighting
the exit correctly you should avoid straighten the wheel to late, which can results
in weaving, in which the vehicle emulates an elongated 'S' shaped path.