Negotiating a corner at high speeds requires great skill and judgement. Each corner varies in length, radius, banking, surface and other factors. In a straight line, the modern motor vehicles is obedient, pleasant with excellent manners. Handled correctly, there is nothing about cornering that should stimulate any fear in a driver. Physicist Sir Isaac Newton would agree that a vehicle does not want to go around a curve - his first law of motion says that a body continues in uniform motion in a straight line unless acted upon by a force. One's body is trying to continue in a straight line and so is the car. Car manufacturers have spent both time and effort to make motor vehicles safer and easier to handle while turning. Yet, some accidents are caused by careless drivers losing control on curves. However, "any curve can be negotiated if a little forethought and common sense are used," says driver instructor Norris Christian.

Understeer and oversteer

According to Mr. Christian, motor vehicles vary in their reaction to centrifugal force depending on the suspension layout, the overall weight, the centre of gravity and more. "Some try to go straight ahead when the wheel is turned," says Andrew Brown, a St. Andrew-based auto mechanic. "There are others who turn readily enough, only to have their rear ends pivot outwards," he adds.

Some vehicles oversteer while other understeer. When the vehicle understeers, it is reluctant to point itself into a corner, thus forcing the driver to turn more and more as he rounds the bend. With an oversteering car, the driver must constantly reduce the amount of steering lock he is using as he motors through a bend.

Additionally, in an understeering car, the motor vehicle continues to drive in a straight line and the driver is forced to turn his wheels progressively. In an oversteering car, the tendency is for the rearwheels to slide first. Most vehicles steer naturally at low speeds. It is only at higher speeds, when the physical forces begin to get stronger, that oversteer and understeer become apparent. "A car might be obedient at 45 mph, but at 65 mph it might handle like a strange object," Brown says. He went on to explain that incorrect tyre pressure and the amount of weight a car is carrying can increase over or understeer without warning.

Corner zones

Mr. Brown explained that a corner could be divided into three segments - the deceleration zone, the turning zone and the acceleration zone.

The deceleration zone begins when speed is first reduced and ends when the wheels are turned into the bend. Poor judgement and improper action and reaction can compound the segments. In the case of a gentle bend in a wide highway, the deceleration zone may involve merely an easing up on the throttle or a light application of the brakes.

In the turning zone, a steady, light throttle application is important.

The acceleration zone requires a gentle increase in power and the reduction of steering lock to return the vehicle to straight-line travel.

All drivers should observe the various bends as they travel the roads and negotiate each in a slightly different way. They should also treat each corner with respect, caution, and apply the necessary defensive driving techniques as the situation dictates.

- P.M.