1. Natural Laws and Vehicle Control 5.3 5.4 Driver Education Legacy High School

2. 2 Perception time and distance The length of time that it takes to Identify, Predict to stop is called perception time. The distance the vehicle travels during this time is called the perception distance. To help reduce your perception time, look 12 or more seconds down the road and keep a following distance of at least 4-6 seconds.

3. 3 Once a hazard or reason to stop is recognized, the length of time you take to DECIDE is called reaction time. –The average driver’s reaction time is ¾ second. The distance the vehicle travels during this time is called reaction distance.

4. 4 Applying pressure to the brake – EXECUTE -- is the braking distance – the slowing and stopping of the vehicle.

5. 5 If you identify a high risk situation, one of the most important things you can do is decrease speed.

6. 6 Stopping distance Braking distance (EXECUTE) Reaction time – distance (DECIDE) Perception time – distance (IDENTIFY -- PREDICT)

7. 7 Estimating stopping distance Use the four-second rule which enables you to to predict a stopping distance under ideal conditions. 1.Pick a fixed point A sign, mark or shadow on the roadway ahead. Note when the vehicle in front of you passes this point. 2.Count off seconds One-thousand-one, one-thousand-two …… 3.If you reach the fixed point sooner than one- thousand-four, you need to increase your following distance.

8. 8 Remember, the four second rule only applies to ideal conditions. Increase your following distance when conditions are less than ideal. –Poor weather – rain, ice, snow, dust storms –Poor visibility – night time driving –Poor road conditions – dirt, gravel –Downhill –Heavy loads

9. 9 Factors that affect braking distance Speed – –Increased speeds mean increased braking distance. –Double speed, braking distance is 4x as long –Triple speed, braking distance is 3x as long. Vehicle condition –Worn tires or shock absorbers increase braking distance. Road surfaces –Wet, snow, dirt, gravel – increase braking distances.

10. 10 Factors that affect braking distance Driver ability –Distracted drivers take longer times to IDENTIFY and PREDICT the need to stop. –Driving under the influence – decreases ability to IDENTIFY and PREDICT the need to stop. Hills –Braking distances are increase when driving downhill – increase following distances. Loads –Double the weight in a vehicle, double the stopping distance.

11. 11 The force which which a moving object hits another object is call force of impact. Three factors control this force –Speed – most important factor in decreasing force of impact, cut speed in half, force of impact is reduced 4x. –Weight – Doubling vehicle weight will double the force of impact. –Stopping distance/time – the distance or time between initial impact and the time the vehicle stops.

12. 12 Vehicles are built to protect occupants –“Crush” or “Crumple” zones – areas of the vehicle that “crumple” to absorb the energy of an impact. –Note that the passenger cabin is relatively undamaged.

13. 13 Air bags Air bags reduce the force of impact between the driver and the windshield and steering column. Air bags are meant to be used in combination with seat belts.

14. 14 Air bags Drivers must have 10- 12 inches between their chest and the steering wheel.

15. 15 Air bags To avoid air bag injury to hands, wrists and arms, keep your hands on the sides of the steering wheel. Keep arms away from the center of the steering wheel. Air Bag Deployment Area

16. 16 Side impact air bags Side impact air bags are designed to prevent or decrease injuries to vehicle occupants in the event of a collision to the side of the vehicle.

17. 17 Seat belts Seat belts are made to hold occupants in place during an emergency. Apply so that lap portion of the belt touches thighs and is snug. Shoulder portion should cross the middle of the chest.

18. 18 Child seats Child seats should be installed in the back seat where air bag deployment will not force the child seat to move.

19. 19 Head restraints Head restraints help prevent or reduce neck injuries (whiplash) during rear end collisions. Adjust the head restrain to reach the middle of the back of the head.

20. 20 Energy absorbing bumpers and cages Most vehicles have energy absorbing bumpers and reinforced passenger compartments. Reinforced doors for side impact protection

21. 21 Safety Glass Vehicles are equipped with “safety glass” –Does not break easily. –Does not “splinter” or have sharp edges. –Breaks into small pieces.