virginia driver education

Virginia Driver Education

Vision, Vehicle Balance and Laws of Nature

Module Three

Virginia Department of Education

Module ThreeVision, Vehicle Balance and Laws of NatureTopic 1 Starting, Securing and Exiting

Topic 2 Vision and Driving

Topic 3 Steering and Braking

Topic 4 Laws of Nature

Topic 5 Establishing Vehicle Reference Points

• Check/set park brake (P) and place

• Right foot on brake pedal, heel on

floor

• Left foot on “dead pedal” for balance

• Key in ignition, and turn toward start

• Check alert, warning lights and gauges

• Adjust ventilation, accessories, etc

• Turn headlights on

Topic 1 - Starting Tasks

• Find a legal, safe parking place

• Stop and set parking brake

• Shift gear selector to (P)ark (Shift to Reverse if Manual Transmission)

• Close windows

• Turn off accessories

• Turn ignition switch to “off”

• Lock ignition switch and remove key

• Unfasten occupant restraints

Securing the Vehicle

• Check traffic flow to rear prior to opening door

• Monitor door swing into adjacent lane or when parked next to another vehicle

• Exit quickly to avoid conflict with traffic• Lock doors• Walk toward rear of the vehicle facing traffic

Exiting the Vehicle

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 look far enough ahead to make

good decisions about speed, lane position, signs, signals, markings, and potential hazards

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

Topic 2 - Vision and Driving

Visual Testing

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

• Fovea VisionVisual Lead, Targeting, Signs, Signals

• CentralReferencing, Path of Travel

• Peripheral VisionMotion and Color Changes

The Three Visual Fields

Effective Use of Visual Fields

Located at the center of the central vision area, the fovea is a small part of the retina and is responsible for our highest visual acuity

The Fovea Vision Area

• Referencing Vehicle Position to Roadway

• Viewing Path of Travel

Central Vision Area (Inner Fringe)

An area 35 to 38 degrees around foveal vision used for:

Central Vision

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

Increases total field of vision to about 180-190 and is used to see:

• Objects to the side

• Movement and color changes to the side

Peripheral Vision Approximately 90 of vision to each side

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

Peripheral Vision and the Driving Task

Night Time Peripheral Vision

• Is reduced dramatically due to lack of light to retina and glare

• While Foveal and Central Vision are also reduced, they become more critical for searching for problems

• Speed• Fatigue• Drugs• Poor weather• Darkness• Glare• Inattention

Vision is Affected by

• Smoke

• Age

• Dirty Windshield

• Poor Windshield Wipers

• Poor night vision

• Night Blindness

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

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.

Poor Depth Perception

As speed increases

• Central vision decreases and blurs

• Peripheral vision decreases

• Changes in steering exaggerate vehicle

movement

VISION FIELDS NARROW

• 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, flashlight, windshield scraper in vehicle

Ways to Improve the Vision Fields

Line of Sight

Line-of-sight is the distance you can see in your path of travel

Line-of-Sight (LOS) Restrictions

Vision is blocked, speed and position adjustments may be needed until LOS is restored

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

A “Target” is an object or place far ahead in the center of your path of travel

Identify the target in this driver’s path of travel

“Target” Far Ahead in the Path of Travel

The Target area is the area drivers must scan to the left and right of the target

Target AREA Provides the BIG Picture

Target Area

• 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

Advantages of Targeting

The driver cannot see anything on the ground in the area outlined above—cars are used to show the size of this area

The Pavement Around Your Vehicle You Cannot See From the Driver’s Seat

Determining Driver Blind Areas

Place markers (cones, people) at the point where the driver can see the marker, (cone, person’s foot) in contact with the ground

Marker (foot or cone)

• 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

Using Lane Position to Maximize LOS

4

5

3

2

1

2-3 Feet

2-3 Feet

Lane Position 1

Positioned in the center of lane with an equal buffer of space on either side

3-6 Inches

Lane Position 2

Allows for 6 feet of space to the right of the vehicle. Used to prepare for a left turn or when avoiding a problem to the right of the vehicle.

3-6 Inches

Lane Position 3

Allows for 6 feet of space to the left of the vehicle. Used to prepare for a right turn or when avoiding a problem to the left of the vehicle.

Lane positions 4 and 5 – straddling the line to avoid a problem within a lane

5

4

Lane Positions 4 and 5

Topic 3 - 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

Hand-to-Hand Steering/Push-Pull

Right Turn

Left Hand Pushes Up from 8 to 11

Right Turn

Right Hand Pulls Down from 1 to 4

Hand-to-Hand/Push-Pull Steering

Used at Speeds below 15 mph

Left Turn/left handLeft hand pulls down, then reaches up to about theo’clock position and continues to pull 11-12 down to the left

Left Turn/right handRight Hand pushes up to about the 11 o’clock position

Used for slow, tight turns - Arms cross on the top 1/3 of the wheel until desired path of travel is reached

Hand-Over-Hand Steering

One-Hand Steering

Is used when:

• Backing straight--hand holds top of wheel

• Backing a trailer--hand holds bottom of wheel

Backing Position

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

AcceleratorBrakeDead Pedal

Left foot “rests” on dead pedal

Foot Pedals

Right foot pivots between brake and accelerator

1. 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

Acceleration Techniques

2. 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

Acceleration Techniques (cont)

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

tires

Braking Techniques

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

2. 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

3. Threshold Braking in an EmergencySlows 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)

4. 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

Methods to Reduce Speed (cont.)

Trail Braking

1. Use controlled braking prior to reaching the curve

3. Accelerate out of the turn

2. Begin easing off brake, and trail brake with very light pressure until halfway through 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.

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

Anti-Lock Braking System (cont.)

• 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

Practice Activating ABS

• There are fewer fatal crashes for cars equipped with ABS

False, some drivers panic and/or release the brake when it pulses

• Don’t use ABS brakes on a slippery surface

False, ABS shortens stopping distance and improves control on a slippery roads

Myths about ABS

• 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

Maintaining Vehicle Balance

Gravity

The natural force that pulls all things to Earth

• Throw a ball into the air and what happens?

• Gravity gives objects their ___________gravity

• The center of gravity is where a body’s mass is ___________

Energy of Motion = Speed x Mass

The white truck and the dump truck are going the same speed

Which vehicle has more energy of motion?

Why?

Effect Of Speed And Weight

• The kinetic energy of a 4,000 pound vehicle traveling at 100 mph is equal to 1.36 million foot pounds – enough to lift a 175 pound man 1.5 miles!

• To stop a vehicle going 60 mph would generate approximately enough heat to boil one-half gallon of water!

Inertia

• Inertia wants to keep these parked vehicles at rest

• Inertia also wants to keep these moving vehicles moving

When driving through this curve, inertia creates the sensation that you are being pulled toward the outside of the curve

Why?

Inertia (cont.)

Because you are traveling in a straight line, and inertia wants to keep you going in a straight line

Momentum = Mass x Velocity

• Momentum is inertia in motion

• Momentum is the product of speed and weight

A small truck filled with potatoes traveling at 20mph has more momentum that a 3,000 lb car traveling at the same speed

As momentum increases so does the potential for damage in a collision

Pitch, Roll, and Yaw

Pitch, Roll, and Yaw are the three axes running through a vehicle’s center of gravity

Pitch

Yall

Roll

Vehicle’s weight shifts backward or forward

Forward Pitch

Changing Vehicle Load from Rear to Front

• Releasing the accelerator• Braking

• Accelerating

• Releasing the brake

Backward Pitch:

Changing Vehicle Load from Front to Rear

Vehicle Pitch

Roll: Vehicle’s weight shifts to the tires

located on one side of the vehicle

Vehicle Roll

Which direction is this driver steering to cause this weight shift? What causes a vehicle roll over?

Vehicle’s rear tires lose traction and weight shifts to one side while opposite rear wheel moves toward front of vehicle

Vehicle YawYaw: Fishtailing

YawNo Yaw

Steering For Balance And Control

• Sit at a safe distance from the wheel

• Use a balanced hand position

• As speed increases, steering input is reduced for turns and other maneuvers

Photo courtesy of ADTSEA

Changes in Speed Affects Balance and Control

• Pushing or releasing the accelerator pedal is the primary method to adjust the speed of a vehicle

• Changes in speed causes weight shifts to front or rear tires

• Increases in speed with steering adjustments causes significant shifts in the vehicle’s weight

Braking Affects Balance and Control

How does braking affect balance and control in a front or rear-wheel drive vehicle?

Effect of Hard Braking and Steering

• Applying hard braking causes weight to shift sharply to the front tires

• If the weight shift exceeds available traction, the tires will skid and steering control is lost (under steer)

Vehicle Suspension System

• Helps to smooth out weight transfers• Helps keep all four wheels on the ground• Helps keep the vehicle level

Accelerating, braking, or steering shifts the vehicle’s weight from tire to tire and affects vehicle balance and control

Describe the driver’s action and how is it affecting this vehicle’s balance?

Steering and Balance

Describe the driving maneuvers that create these tire footprints

Maintaining Vehicle Balance

Describe the driving maneuvers that create these tire footprints

Maintaining Vehicle Balance (cont.)

Vehicle Load

Vehicle load capacity includes the combined weight of people, liquids and cargo that the vehicle is designed to safely handle

Effect of Load On Vehicle Balance

What could occur if the driver of this vehicle made a quick steering maneuver?

Photo courtesy of AAA Foundation

Vehicle Over Load

• Operating a vehicle above the Gross Vehicle Weight Rating (GVWR) compromises safety

• Frame, suspension, brakes and tires are not designed for weights above the rating the manufacturer has set

Standard Vehicle Reference Points

LEFT Reference Point

6 inches from line or median

3 feet from line or median

• Relates a part of the vehicle to some part of the roadway• Know your vehicle placement within a lane at all times• Maneuver in confined places

• Relates a part of the vehicle to some part of the roadway• Know your vehicle placement within a lane at all times• Maneuver in confined places

RIGHT Reference Point

6 inches from line or curb

3 feet from line or curb


Left Side Reference (3-6 Inches)

When you look at the curb, pavement line, or edge of the road, it appears to line up about one foot in from the left edge of the hood


Used for:• Lane Position 2• Preparing for a left turn• Determining position for

parking on the left side of a one-way street (3-6 inches from the curb or line)


Left-Side Reference Point

Your vehicle is 3-6 inches from the curb, pavement line or edge of the road when the line appears near the center of the hood


Right Side Reference Point

Are Used:• To know where the curb or line is

located• For Lane Position 3• For parking


Right Side Reference Points

To Position Vehicle Three Feet Away

When you look at the curb, pavement, or edge of the road, it appears to line up with the middle of the right- half of the hood


• To position for a right turn or for

• Lane Position 1

Right Side -- Three Feet AwayStandard Vehicle Reference Points

To position 3-6 inches from the line in front of your bumper, stop when your line of sight runs under the side view mirror to curb in front

Reference point

Line of sightReference Point

Front Limitation


• At intersections• At a stopped

position• When parking• At a crosswalk

You will need to know where the front bumper of your vehicle is when you are:

STOP LINE


Front Limitation

Front LimitationWhen you look at the curb line it appears to line up

with the side view mirror


Rear Limitations

LEFTWhen you look back over your left shoulder, the curb or line appears to be in the middle of the left rear window

RIGHTWhen you look back over your right shoulder, the curb or line appears to be near the rear window corner


Rear Limitations – How They are Used

LEFTWhen backing to know where your rear bumper is

RIGHTWhen backing around a corner, it’s the pivot point for turning, such as backing into a perpendicular parking space


virginia driver education

Documents

foveal vision

sideperipheral vision

lane peripheral vision

total field of vision

vehicle position

vehicle balance

visual testing visual

color changes