The Science of Security Driving

As we (ISDA) have posted in the past, researchers define driving skill as the driver’s “ability” to use the vehicle’s “capability.”

The researchers express driving skill as the percentage of the vehicle a driver can use before losing control of the vehicle. If a driver can use 50% of the vehicle, they define him/her as a 50% driver, if they can use 80% of the vehicle, they are an 80% driver. The same research also has found that the average driver can only use 40% of the vehicle’s capability.

Using 80% or above of the vehicle’s capability would more than likely only happen during an emergency (accident or ambush). But what percentage of the vehicle does a Security Driver use while maneuvering through the day to day mundane chore of moving the boss from Point A to Point B, such as driving up to an intersection and slowing down – stopping at a red light – driving on an off ramp or around a corner?

To answer that question, ISDA conducted an experiment, using a G-Meter, measuring how much of the vehicle’s capability is used during normal driving routine, one absent of an emergency. What we found interesting was how little of the vehicle’s braking and cornering capacity result during the daily driving routine.

The Results

The vehicle used in the experiment was capable of .9 G’s braking and .78 G’s cornering, which means the vehicle could absorb 90% of its weight braking (.9 G’s) and 78% (.78 G’s) of its weight cornering. Keep in mind that the average driver can only use 40% of the capability of the vehicle.

As we drove up to a stop sign and applied the brakes, coming to a leisurely stop, the G Meter indicated that we used 27.8% of the vehicles capability to stop. When driving around a corner, we used an average of 28% of the vehicle’s capability. The end result is; when driving through the day to day routine, a Security Driver uses very little of the vehicle’s capability.

A Society of Automotive Engineers paper has indicated that using 30% to 35% of the capability of the vehicle is the ‘Comfort Zone’ for most drivers. If they use more of the vehicle (apply more G’s on the vehicle), the research notes that the driver gets “anxious” (The engineering way of saying scared). But if an emergency popped up a driver would instantaneously have to go well beyond their Comfort Zone and use a minimum of .8 to .9 G’s, braking or cornering to avoid the emergency.

That’s what training is about, training students to use a minimum of 80% of the vehicle and to accomplish that in a time frame measured in tenths of seconds. Basically to get drivers past their comfort zone, and (as defined by the SAE) become 80% drivers.

To put this in the context of Security Driving, a Security Driver could drive for weeks, months years and never need to drive past the comfort zone of using 40% of the vehicle. But when confronted with an emergency, accident or vehicle violence, and in the blink of an eye, the driver will need to have the ability to go past their comfort zone and use a minimum of 80% of the vehicle. But isn’t that part of the Security Drivers job description; have the measured ability to use the vehicle’s capability.


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