AAA Kentucky Driver Training

Introduction decisions/mile 1 per sec) Decisions relate to adjusting time, space, and visibility within the limits of available traction for operating conditions (law, other users, road environment, risk) Experienced driver relies on driving habits Safe driving habits alter risk in a positive manner

Introduction(2) A safe driving career requires driving habits that encompass proper attitude and proper skill To accomplish this, an individual must acknowledge risk, understand the driving process, and desire to constantly strive for improvement

Introduction(3) Habit development –Know what to do –Have a desire to do it –Demonstrate that you can do it –Overcome resistance to change –Understand correct, or incorrect, performance –Practice correctly at least 25 times –Ability to do correctly without conscious thought

Introduction(4) Classroom presentation provides the basic knowledge BTW demonstrates the process YOU MUST PROVIDE THE ATTITUDE AND THE DESIRE TO CONSTANTLY IMPROVE!

Dynamics of Driving Vehicle Response Human Response

Natural Forces Affecting Driving Gravity (the pull of earth's mass on object's at or near earth's surface) Friction/Traction (resistance to motion between two bodies in contact) Kinetic Energy (energy associated with mass and motion) Impact, i.e.. transfer of energy (absorption of kinetic energy with the release of other forms of energy) Inertia (objects at rest or in motion will remain at rest or in motion until acted upon by an outside force)

Dynamics of Driving Driver controls speed and placement through use of Brakes (slows/stops tire rotation against road) Accelerator(causes drive wheels to rotate against road) Steering(front wheels turn and rotate causing direction change)

Vehicle Response Every control input depends on the tire/driving surface interface Courtesy of Goodyear and ADS

Vehicle Response The effectiveness (time/distance) of each control input depends on Newton’s Laws of Motion You can’t beat natural law, regardless of age, reflex, or skill! You must allow for the effect!

Vehicle Response The tire/driving surface interface is referred to as friction, or traction Friction is the horizontal force required to move an object (F) divided by the weight of the object (w). Friction is influenced by Surface type (asphalt, concrete, dirt, grass, gravel) Surface contour –Slope(+/-) –Curve (horizontal vs centrifugal / bank) Surface condition (wet, oil, leaves, snow, ice, standing water)

Vehicle Response Weight Shift During a stop During acceleration During a turn Inertia Effect

Vehicle Response When turning if inertia overcomes the friction content of the surface the vehicle leaves its intended path Locked wheels: Vehicle continues in direction it is heading regardless of steering input- reduce speed before the turn! Inertia Effect When cornering, tires tend to fold. Underinflated, contact with the rim will be lost. (AIR LOSS MAY OCCUR)

Vehicle impacts solid object at 35mph, it begins to crush and slow down (transfer of energy). Each inch of crush dissipates about 1 mph of energy. Body continues forward at 35 mph (inertia). Vehicle stops in 1/10 sec., body impacts 1/50 sec later, body stops in 1/100 sec.

Vehicle impacts solid object at 35mph, it begins to crush and slow down (transfer of energy). Belted body tends to keep moving forward but belt retards forward motion. Seat belts are fastened to vehicle frame allowing body to decelerate with vehicle collapse. Air bag further retards forward motion. Time for body to stop reduced from 1/100 sec to less than 1/10 sec.

Vehicle Response Relationship of Kinetic Energy, Mass, & Speed

Vehicle Response Energy increase = the square of the speed increase Damage and injury increase in proportion to the energy involved in a crash

Vehicle Response Braking distance increase = the square of the speed increase f = 0.75 dry f = 0.45 wet f = 0.20 ice Braking distance does not include PRT distance

Vehicle Response Time required to accelerate The gap to enter traffic, or cross an intersection, depends upon the rate of travel of oncoming traffic. Use a safety margin! Turning: Critical Speed Critical speed is the absolute maximum speed at which a vehicle will travel a specified turn radius (stay in its intended path) with a given friction value. Do not attempt a normal intersection turn in excess of 10 to 15 mph!

Human Response Perception/reaction time has 5 components Search Identify Predict Decide Execute PRT is the time it takes to recognize and react to a hazard.

Human Response Average PRT is 1.5 seconds During PRT a vehicle travels at a constant speed PRT is increased by complexity of situation choice of available actions distractions alcohol/drug impairment age 35mph = 51fps 55mph = 80.63fps 65mph = 95.29fps

Total Response Time ft54.44ft ft ft134.44ft254.89ft ft187.77ft330.13ft f = 0.75 dry f = 0.45 wet f = 0.20 ice 76.65ft 54.44ft131.09ft 90.75ft167.4ft ft 280.8ft Total Stopping Distance from 35mph - various conditions PRT distance + Braking distance = Total Stopping Distance

Stopping & Space Cushion React Dist + Brake Dist = Total Stop Distance React time = 1.5 sec Friction = 0.75

The Safe Driver A safe driver controls risk by managing time, space, and visibility within the limits of available traction. »Steve Bail Driving Instructor AAA Kentucky

Becoming a Safe Driver Learn to handle vehicle competently through range of maneuvers & conditions Recognize & identify hazards and handle successfully Keep adequate space margins Maintain proper speed for conditions To obtain these objectives a driver must learn and use …... Proper Visual Habits