Virginia Department of Education Module Three Vision and Driving Establishing a Safe Lane Position Accelerating and Braking Vehicle Reference Points

Review Mod 2 ________________________ Establishing a “Starting Procedure” Adjustments Seat Mirrors Seat belts Head Restraint (if adjustable)

Left foot “rests” on dead pedal Foot Pedals Dead Pedal Brake Accelerator Right foot pivots between accelerator and brake Left foot “rests” on dead pedal

Basic Maneuvers -- Steering Holding the upper half of the wheel can result in excessive steering, air bag injuries, and upper body fatigue Hands located on lower half of the wheel offers: Relaxed, balanced control Reduces unwanted steering wheel movement Improves stability by lowering the body’s center of gravity  

Maintaining Vehicle Balance Vehicle balance is the distribution of the weight of the vehicle on the tires Optimum balance is reached when the vehicle is not moving or is moving in a straight direction at a constant speed As soon as the vehicle accelerates, brakes, or turns, the balance is changed and the weight transfer changes the size of the tire patches **Pitch- Accelerate & Brake **Roll- Left to Right **Yaw- Fishtail

Using Lane Position to Maximize LOS Select the lane position that gives you the best line of sight and safest path of travel Lane positions are based upon an average lane size of 12-feet wide, and a vehicle 6-feet wide 1 2 3 4 5

Topic 1 - Vision and Driving Drivers base about 90% of all driving decisions on what they see, and 10% on what they hear or feel Drivers must be able to see far enough ahead to make good decisions about speed, lane position, signs, signals, markings, and potential hazards Drivers should search at least 20 seconds ahead in the path of travel to evaluate potential risks

Drivers must learn proper visual skills Drivers must learn proper visual skills. Proper searching is a learned skill. “The eyes don’t tell the brain what they see, the brain tells the eyes what to look for.”

What does your vision score mean? If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance If you have 20/70 vision, you can see clearly at 20 feet what should normally be seen at 70 feet.

Visual Testing Visual acuity is the measurement of the details which can be seen in optimal light conditions

Drivers must be able to see near and far--close enough to read the speedometer, and far enough ahead to see/adjust for hazards

Effective Use of Visual Fields The Three Visual Fields Focal Vision Visual Lead, Targeting, Signs, Signals Central Referencing, Path of Travel Peripheral Vision Motion and Color Changes

Focal Vision Focal vision is primarily responsible for object recognition Focal vision is limited to the central two degrees of vision Focal vision allows one to see clearly in order to recognize objects and read displays

Central Vision An area 35 to 38 degrees around focal vision used for: Referencing Vehicle Position to Roadway Viewing Path of Travel  

Central Vision at Night The human eye’s field of vision is much smaller without the help of natural light Depth perception, visual acuity, and color recognition are all compromised at night Minimize glare by looking at the bottom right of the road to avoid approaching headlights Keep it dark in the car Slow down to give yourself longer to react

Approximately 90 degrees of vision to each side Peripheral Vision Approximately 90 degrees of vision to each side Increases total field of vision to about 180 degrees and is used to see: Objects to the side Movement and color changes to the side

Peripheral Vision and the Driving Task Drivers use peripheral vision to: See color and object movement See signal changes, road signs, warning lights on the dashboard Monitor traffic Stay within the lane

Night Time Peripheral Vision Is reduced dramatically due to lack of light to retina and glare While Focal and Central Vision are also reduced, they become more critical for searching for problems

Vision is Affected by Smoke Age Glare Dirty Windshield Fatigue Drugs Poor Windshield Wipers Poor night vision Night Blindness Glare Fatigue Drugs Poor weather Darkness Speed Inattention  

Depth Perception Need both eyes to judge the distance between two objects Depth perception allows you to: judge gaps in traffic when turning, merging, or passing judge distance when approaching a vehicle or obstruction Are these line parallel?

Signs of Poor Depth Perception Stop too far from the stop line or intersection Stop too close to vehicles ahead Move into gaps that are too small Look for gaps that are larger than needed to perform a maneuver Follow other vehicles at unsafe following distance Hit parked cars when parking Have “close calls” when entering traffic, passing, etc.  

Speed Affects Vision Central vision decreases and blurs Peripheral vision decreases Changes in steering exaggerate vehicle movement VISION FIELDS NARROW

Ways to Improve the Vision Fields Clean windows—inside and out Clean lights—be sure they work Check defroster and wiper blades Remove any objects that interfere with vision Adjust mirrors properly Keep sunglasses and windshield scraper in vehicle

Line of Sight Line-of-sight is the distance you can see in the direction you are looking

Line-of-Sight (LOS) Restrictions When vision is blocked, speed and position adjustments may be needed until LOS is restored

The space the vehicle will occupy while traveling to the target area Path-of-Travel (POT) The space the vehicle will occupy while traveling to the target area

Examples of Path-of-Travel Restrictions Space is not available for the vehicle Narrow lane and no shoulder Vehicle stopped or blocking intersection

“Target” Far Ahead in the Path of Travel A “Target” is an object or area far ahead in the center of your path of travel Identify the target in this driver’s path of travel

Target AREA Provides the BIG Picture The Target area is the area drivers must scan to the left and right of the target Target Area

Advantages of Targeting Easier to track vehicle in a straight line Driver looks far ahead of the vehicle, and at the same time gathers information close to the vehicle Driver can plan ahead to better manage risks Targeting develops visual skills essential for managing traction loss and steering control  

Effect of Speed on Vision and Steering VISUAL FIELDS NARROW As speed increases: central vision narrows and blurs peripheral vision decreases changes in steering will cause exaggerated vehicle movements

Effect of Speed on Vision As speed increases, look farther ahead of your vehicle to increase line of sight (LOS) and search your path of travel (POT) to: allow more time to gather information; lengthen total visual field, giving more time for adequate response; and place more space between other users and your vehicle so sudden steering changes are held to a minimum.

Determining Following Intervals Fixed Object or Shadow One Thousand One One Thousand Two One Thousand Three One Thousand Four

Time, Speed, and Distance Time, Speed and Distance on Dry Pavement Vehicle Ft./Sec. Speed Travel Following Interval 2 Sec. 3 Sec. 4 Sec. 1/2 sec 3/4 sec Total Steer Brake Brake Dist. Dist. Dist. 30 mph 44 f/s 88 ft. 132 ft. 176 ft. 22 ft. 33 ft. 80 ft. 40 mph 58 f/s 116 ft. 174 ft. 232 ft. 29 ft. 44 ft. 125 ft. 50 mph 74 f/s 148 ft. 222 ft. 296 ft. 37 ft. 56 ft. 190 ft. 60 mph 88 f/s 176 ft. 264 ft. 352 ft. 44 ft. 66 ft. 275 ft. 70 mph 104 f/s 208 ft. 312 ft. 416 ft. 52 ft. 78 ft. 385 ft. Formula for approximate feet per second traveled: Speed + ½ speed = FPS traveled

Following Intervals 2 Seconds… Allows driver time to steer out of problem areas at all listed speeds on a dry surface and stop before problem areas at speeds under 35 mph. 3 Seconds… Allows driver time to steer out of problem areas at all listed speeds on dry surface and stop before problem areas at speeds to 45 mph. 4 Seconds… Allows driver to steer out of problem areas at speeds up to 65 mph on dry surface and stop before problem areas at speeds to the legal limit of 65 mph. Most factory equipped passenger car tires are not designed to steer out of problem areas at speeds beyond 75 mph. At such speeds, speed rated tires are required due to increased tire heat and reduced traction caused by excessive sidewall flexion--especially on curves or when turning.

Topic 2- Accelerating and Braking Covering the Accelerator Used for a smooth transition from braking to accelerating Allows the vehicle to coast which may speed up or slow down the vehicle Permits the driver to be prepared for any needed acceleration

Acceleration Techniques Progressive, Smooth Acceleration Heel pivots foot from the brake to the accelerator Gently apply pressure to the accelerator pedal to gradually increase speed to minimize backward pitch and maintain vehicle balance How do you know if you are and smoothly gaining speed?

Acceleration Techniques (cont) Thrust Acceleration Typically used when passing or merging into higher speed traffic Greater pressure is applied to accelerator pedal to rapidly increase speed without losing tire traction

Braking Techniques Smooth braking technique: Is a trait of a skilled driver Saves wear and tear on the brake system and tires

Methods to Reduce Speed Release the Accelerator Most frequently used method to slow vehicle speed Gradually reduce pedal pressure to avoid abrupt changes in speed

Methods to Reduce Speed Controlled Braking - When releasing the accelerator is not enough Check the rear view mirror Release accelerator and apply smooth, steady pressure on the brake pedal For a smooth STOP, gently ease off the brake a few seconds before stopping to reduce the vehicle’s weight shift so the car does not pitch forward then backward during the final phase of stopping

Methods to Reduce Speed (cont) Threshold Braking in an Emergency Slows the vehicle as quickly as possible without locking brakes or losing traction Release accelerator while checking traffic behind Exert forceful pressure on brake pedal and you will feel the vehicle weight shift forward If you feel the wheels begin to slide, ease the pressure on brake pedal so the tires can begin rotating again

Methods to Reduce Speed (cont.) Trail Braking – Used for Sharp Turns Occurs at the transition point where you slightly reduce pressure on the brake pedal to allow the vehicle to begin to regain speed before applying the accelerator

Trail Braking 1. Use controlled braking prior to reaching the curve 2. Begin easing off brake, and trail brake with very light pressure until halfway through the turn, 3. Accelerate out of the turn

Anti-Lock Braking System (ABS) ABS allows maximum stopping force without locking up the brakes (skidding) If standard brakes are applied too hard, the wheels "lock" or skid, and you lose steering control.

Anti-Lock Braking System (cont) If steering control is lost, the vehicle skids in a straight line wherever it is going ABS is an anti-lock/anti-skid brake system that allows the driver to steer during hard braking

Anti-Lock Braking System (cont.) The ABS warning will come on when there is a problem with either the ABS brake system, normal brake system, or the brake fluid is low in the master cylinder or the ABS brake system To find out if a vehicle is equipped with ABS, turn on the ignition and check the instrument panel for the ABS indicator light  

Practice Activating ABS In a parking lot, go 20-25 mph and execute an emergency stop to engage ABS Keep your foot firmly on the brake even when you feel the brake pulsate and/or hear noise This computerized pumping action can pump the brakes up to 15 times per second