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In the July 1997 column, we compiled a top 10 list for emergency vehicle operators. One item on the list involved emergency braking. This column will expand your knowledge of emergency braking procedures.
Emergency braking is probably the least known and the most misunderstood operation that we perform behind the wheel of an emergency vehicle. Yet it is probably the most important factor in accident avoidance. But why?
When I teach an emergency vehicle operators' class, I will ask the question: "How many apparatus operators in this class have ever had to make a life-or-death emergency stop in the fire apparatus?" Inevitably, two or three operators will raise their hands, in a class of 30 operators. That means only about 10% or less of the operators that I have surveyed have ever had to make an emergency stop.
You will have a better understanding of this phenomenon if we examine events closely and in chronological order. We start at the fire station and find the apparatus backed into the bay, positioned similarly to a NASA rocket, ready to blast off. Then we add the next component, the apparatus operator in this case a new operator; the next alarm will be his first as an emergency vehicle operator.
The alarm sounds. He feels a rush of adrenaline as he mounts the apparatus and begins to respond. He is tentative, even nervous, as he responds at a respectable 20-30 mph. Time passes, he drives to a few more alarms, his confidence builds, his speed increases to 30-40 mph.
Then, his attitude changes. This fire apparatus driving is easy; people get out of his way when he turns on his lights and sirens (theoretically), the fire apparatus handles like a car, speed increases to 40-50 mph. A few months, then a few years go by.
As time passes, his confidence increases proportionally with speed and safety decreases, as complacency sets in. Now the driver has 10-15 years' driving experience, everyone gets out of his way and there is no situation that his driving abilities cannot handle. EXCEPT he has never had to make a sudden serious emergency stop.
Think about it. How many emergency stops have you had to make in your driving career? Have there been any? If you've never had to make a sudden stop, it now becomes much easier to respond at 50-60 mph. Maybe if apparatus operators had the awesome experience of bringing a 40,000-, 50,000- or 60,000-pound fire apparatus to an emergency stop at 50 mph, maybe they would not do 50 mph anymore. It becomes really easy in a modern fire apparatus to go really fast if you have never really had to stop.
How do you train operators on emergency braking procedures? First, you must identify the correct braking procedure. Three braking procedures come to mind.
The first emergency braking procedure is brake lockup. This occurs when the vehicle operator panics, holds the brake pedal to the floor in a vehicle not equipped with anti-lock brakes. When lockup occurs, the driver loses all operational and steering control. Why? It's a matter of physics. The driver's ability to keep the vehicle under control is a direct result of the friction between the vehicle's tires and the road surface.
When the brakes lock up, most of the friction is lost, causing the apparatus to skid out of control. If you are trying to steer when the brakes are locked, you will continue to straighten even if the wheels are turned to the left or right. Also with the brakes locked up, the friction is drastically reduced and it takes a much greater distance to stop. This braking procedure is obviously not the answer.
Next, we investigate the stab braking procedure. Stab braking occurs when the operator continually activates the brake with quick brake depressions or by pumping the brakes. With stab braking, there are multiple brake applications in a short period of time, thereby depleting the air supply for the brakes. This in turn could prematurely activate the maxi-brakes on the apparatus which could cause the brakes to lock up. Remember, under U.S. Department of Transportation (DOT) standards maxi-brakes on the apparatus will begin to activate at 60 psi. Although stab braking is better than locking up the brakes, the most efficient, safe, braking procedure is threshold braking.