Emergency Maneuver vs. Cornering
Many training programs teach an exercise called Lines and Apexes. In this context, a ‘line’ refers to the ideal path a driver follows through a corner, and an ‘apex’ is the precise point at which the vehicle comes closest to the inside edge of the turn. The goal of the exercise is to train the student to maximize their speed through a corner; from a vehicle dynamics viewpoint, that is a different skill set than operating a vehicle in a sudden emergency scenario.
In an emergency, the required turning, steering, and braking are unpredictable—that’s what makes it an emergency. When faced with one, the driver reacts instinctively, operating the controls in a sudden situation. From a vehicle dynamics perspective, emergency maneuvers differ from normal cornering, where energy is imparted gradually and smoothly. It may not feel slow in the car, but by vehicle dynamics standards, it is.
There is a significant difference between the energy applied to a vehicle as it goes through a corner at speed and the energy applied during an emergency maneuver. In an emergency, a massive spike of energy is applied to the vehicle’s center of gravity.
The driver does not purposely put a high spike of energy on the vehicle. Consider that if they are moving at 40 MPH (65 KPH) and an obstacle is 75 feet (22.5 meters) away, they are 1.25 seconds from the obstacle. Since it is a surprise, the driver’s reaction time will eat up at least half a second. At that point, the driver has to turn the steering wheel to create enough energy to move the vehicle away from the obstacle, and not too much energy so that it would cause the vehicle to go out of control, and do all that in a couple of tenths of a second, in the blink of an eye.
The event’s success depends on speed, how quickly the steering wheel is moved, and the student/vehicle capability. Racing fans may disagree, but when a car’s center of gravity is hit with a large energy spike, even the best racer is challenged. To perform an emergency maneuver, the driver has only about 75% of the handling capability of an average race car. That is one hell of a dance. The skill for driving out of emergencies is not learned by driving lines and apexes. This skill is learned in the lane-change exercise. The exercise’s dimensions, entry speed, and the timing of the lane-change signal must be synchronized. When it all works together, it becomes one of the most valuable skills to teach.
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