Braking distance


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A simple slide show to explain one reason why distracted driving can be deadly.

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  • Just how much do you know about the effects of speed on braking distance and time-to-stop? Surprisingly, most drivers severely underestimate the time needed to bring a car to a stop at almost any speed. Your teen, or new driver, should be aware of some simple facts before getting behind the wheel on their own.
  • Braking distance

    1. 1. What Will You Teach Them About: Braking Distance Time & Speed
    2. 2. FIRST: Do you really know just how fast you are really going, in feet-per-second?A simple method, that is fairly accurate, is to add ½ of yourspeed to the speed itself, with the resulting sum equaling yourspeed in feet-per-second.If you are driving at 50 mph, for example, the formula: S + ½ S = S (fps),would translate to the Speed (50) + ½ S (25) = 75 fps. (For thoseof you with a calculator, you can multiply your speed by1.467, and get 73.35 fps)This means that, if you look down to simply answer your cellphone, or change a radio station, for only one second, youhave, literally, traveled 75 feet “blind”. Yet you do it willingly, andwithout thought; (although I think you would call me manyunkind names if I reached up and held my hands over your eyesfor that SAME one second!)
    3. 3. Here’s a really simple chart to show you this speed conversion a little more easily.
    4. 4. SECOND: Do you know how long it takes for the car brakes to stop the car?Another simple formula for basic braking distance is: (Speed * 1/10 Speed) / 2 = Stopping Distance in feet EXAMPLE: at 50 mph; (50 * 5) /2 = (250) /2 = 125 feetKeep in mind that this is ONLY the efficiency of the brakes. Thedriver has to be efficient also. Studies have shown that, onaverage, it takes from ¾ to 1 ¼ second for a driver to react to anyparticular danger (see it, remove foot from gas, apply brake)BEFORE the car’s brakes get a chance to actually stop the car.Using an average of 1 second reaction time, at 50 mph, the driverwill travel about 75 feet before he touches the brake pedal. Addthat to the 125 feet of stopping distance, and the TOTALstopping distance would be 200 feet!
    5. 5. Of course, the 200 feet distance assumes the driver is actually paying attention! ADD another 75 feet if he is distracted by the ringing cell phone for just 1 second;ADD another 150 feet if she turns around to check the baby in the back seat for 2 seconds;ADD another 225 feet if the driver is distracted by changing the radio, or a CD, for 3 seconds; . It all ADDS up to increased stopping distance…which can be deadly
    6. 6. This chart uses an average reaction time of ¾second, but you’ll see the overall distances are about the same.
    7. 7. Speed, distractions and stopping, individually, don’t usually cause fatal or injury collisions.Don’t rely on simple platitudes, like “SPEEDKILLS”, when teaching your child to drive. Theyknow, as well as you and I, that IF speed kills, therewould be no race car drivers or astronauts.However, when speed is ADDED to the task ofdriving, along with distractions, uncertainty andinexperience in control and danger recognition, a verydeadly “cocktail” of ingredients can be the result.On the next slide, we can see a simple example of thisconcept.
    8. 8. VODKA – 1 shot is relatively harmlessTEQUILA - 1 shot is relatively harmlessRUM - 1 shot is relatively harmlessGIN - 1 shot is relatively harmlessTRIPLE SEC - 1 shot is relatively harmlessCOCA-COLA – relatively harmlessIndividually, these alcoholic drinks are “relatively” harmless. But, whathappens if we put them all into ONE glass, mix them up, and call it a: Long Island Iced Tea
    9. 9. Similarly, driving is not a simple “one-thing” event; like the Long Island Ice Tea, it is a cocktail of events, that MUST be carefully managed.PERCEPTION – staying focused and identifying potential dangersCOGNITIVE – thinking about what to do, when to do it, and how to do itbestMANUAL – the physical aspect of driving; steering, pedals, shiftingAUDITORY– listening for horns, barking, yelling, etc. that may warn ofdangerVISUAL – examining the driving environment for safety, traffic, and path oftravelWhen mixed together, these ingredients create a safer driver, a more awaredriver, and a driver who is ready to react to his or her driving environment. Isn’t that EXACTLY what you want your teen driver to become?
    10. 10. Teach them facts, not opinions; realities, notdreams. Let them know that, while driving is oneof the most dangerous things they will ever do, itCAN be managed safely, but only if it is treatedas a TASK that needs to be accomplished withFOCUS and determination.In other programs, we will be covering, or havealready covered, the dangerous aspect of drivingand what to do about it.