Defensive Driving Collision Prevention Theory

According to the National Highway Traffic Safety Administration, "accidents" are defined as unexpected, unavoidable events. And in many people's minds, the word also suggests an event due solely to fortune or chance. But crashes and injuries aren't unforeseeable or unavoidable at all. In theory, accidents are both predictable and preventable.

In other words, you don't have to be psychic to predict if a driver runs a red light, speeds, drives drunk or breaks other rules of the road that the likelihood of a crash goes way up. And in the event of a car, bicycle or motorcycle crash, those who are not buckled up or not wearing helmets are, predictably, more vulnerable to injury and even death.

No one likes getting into a collision. It can be quite inconvenient, not to mention expensive. But making certain choices can help to minimize your chances of crashing. The goal with defensive driving is to be aware of your surroundings and anticipate events so you can avoid getting involved in an emergency driving situation. It begins with understanding your driving choices and then making the right ones.

Physics
Various natural and environmental factors affect the driving task and contribute to collision potential.

A. Kinetic Energy (momentum) - An increase in driving speed requires an increase for that vehicle in stopping distance, as the vehicle has gained more momentum. Allowing enough stopping distance for the vehicle is the only sure way to offset the momentum of the vehicle.

B. Impact - At impact in a car crash, the "G" or gravitational forces in a collision are astronomical. Consequently, you must make all efforts to stay in the car, buckled in your seat belt, to survive the force of the impact. These "G" forces, if in effect for longer than a millisecond, would tear apart a human being. In a crash, these forces are impacted on the occupants for only a fraction of a second, but still contain enormous power. Stay secured in the passenger compartment, which is the safest place to be at all times.

Special Awareness
It is vital for all drivers to be aware of the environment in which they travel, other drivers around them, and the vehicles they control.

A. "Rear-Ender"- This is the most common collision type and is nearly always the fault of the car in the rear. When you tailgate you do not leave enough stopping distance between yourself and the vehicle you immediately follow. The rear-end collision is often the result of following too closely but can be prevented by signaling early for all turns, stops and lane changes. It is also a good idea to frequently check the traffic behind your vehicle, and if tailgated, change lanes immediately. Always be aware of tailgaters or large vehicles following too closely or gaining rapidly from behind, and take appropriate action to avoid conflict. If you are in heavy traffic or are nearing an intersection with a red light, and you see the driver behind you following too closely or approaching rapidly, try the following:

• Attempt to warn the driver behind you by tapping your brakes.
• If moving forward will interfere with cross traffic and thus create another hazard, press your brake pedal and allow your vehicle to absorb the impact. Hold onto your steering wheel, but do not lock up your arms. Rest your head against the head restraint. If you are not wearing your seat belt, try to use your arms and hands to protect your face from impact.
• Keep a firm grip on the steering wheel, with your arms bent so that they do not break. Chances are you may be pushed forward or even sideways when hit from behind and will still need to maintain control.
• Your seat belt will prevent your face and upper torso from hitting the steering wheel or windshield, so be sure to wear it. Most cars today have headrests, which will help minimize the whiplash factor. Rest your head against your head restraint to maximize protection for your neck.

1. From the Front

• If possible, avoid head-on collisions and the inevitable impact. Attempt to maneuver so the approaching vehicle hits your car from the side.
• If your vehicle is going to be hit from the front, use your arms or hands to protect your face, and throw yourself across the seat to avoid hitting the steering wheel or windshield if you do not have a shoulder harness on.
• Be careful when protecting your face. Air bag devices deploy in front-end impacts at approximately 35 mph. Use caution when placing your hands in front of your face as the air bag could push them into your face (the shoulder strap of your seat belt will prevent your face from hitting the dashboard).

2. From the Side

• Keep both hands onto the steering wheel with your arms bent to keep from being thrown against the side of your car.

C. Light Rain / First Rain - The first rain often leads to a dangerous condition in which to operate a motor vehicle. This early rain lifts the oil up from the road surface, yet does not completely wash away the slippery substance. Unfortunately, many drivers are generally unwilling to slow down to a level that the first rain requires. Light rain tends to be ignored by people who continue driving as if the roads were clear and dry. What they fail to realize is that this light rain makes the road slick and dangerous. Speed should be dramatically reduced, with extra stopping distance allowed and extreme caution exercised. It is important to remember that when road conditions and surfaces change, braking distance and traction change as well.

Statistics

• The leading cause of expressway collisions is "FOLLOWING TOO CLOSELY."
• 50% of all crashes are caused by drivers 16 - 24 years of age.
• 24% of all collision fatalities involve drivers 16 - 24 years of age.

Car Design

Car manufacturers design vehicles with safety in mind. Familiarize yourself with your vehicle's safety features, as they assist in collision prevention.

A. Windshield - The purpose of the windshield is to protect the driver and passengers from the environment. Fibers and plastic are often laminated between the glass, so the windshield will not shatter completely in a crash. A clean, clear windshield is a vital element for driving, yet it is often overlooked as a safety tip. Properly functioning windshield wipers are not just useful during rain or snow, but may also clear visibility in case of sand or dust storms. (Under ordinary storm conditions, windshield wipers should be able to clear fog, snow or rain.) Even if you are the most skilled driver on the road, you still cannot safely control your vehicle if visibility is impaired. Prior to driving, it is imperative that you check your visibility to ensure it is not hampered by a dirty windshield. It is illegal to drive a vehicle on the roads if your vision is impaired to the front or rear by a poorly maintained or defective windshield or rear window. Any vehicle manufactured after July 1, 1970, must have a windshield.

Note: The vehicle's windshield should not have any objects such as stickers affixed to it as to obstruct your visibility. Signs or hanging objects from the rear view mirror are also prohibited. Tinted safety glass is only allowed if it conforms to U.S. Department of Transportation standards and does not affect the safe operation of your vehicle.

B. Crumple Zones - Cars are designed to collapse in a collision in order to absorb the force on impact. The "accordion" look often seen in cars involved in serious crash is affected by design, whereas the energy of the collision is dispersed throughout the vehicle's crumpled mass. Assuming the driver and any passengers remain in the vehicle, safely buckled, this design feature dramatically reduces injury in crashes.

C. Truck Under-Ride - There is a bar affixed to the rear of large trucks that extends down from their trailer designed to prevent cars from going under them during a crash. As rear-enders are the most common collision type, this helps to prevent the tops of vehicles from being sheared off by the trailers of large trucks.

D. Mirrors - Each vehicle must be equipped with a mirror placed where the driver is able to see any vehicle behind traveling in the same direction. Federal law requires a minimum of two mirrors: an inside mirror and a mirror on the driver's side. You must be able to see vehicles that overtake your car from behind at a distance of at least 200 feet. If your view of the rear from the inside mirror is blocked, or if your windows are tinted, your vehicle must have outside mirrors mounted on both the left and right sides.
 
 

Emergencies
Driving on the roads of Delaware requires attentiveness, skill, a vehicle that is responsive, a little luck, and a subconscious mind that can quickly react. When an emergency occurs on the road, the decision to act must be a split-second one, and you must know instinctively what to do. The following will prepare you for an emergency driving situation:

A. Brake Failure - Many factors can cause brake failure. Wet brakes that result from driving through puddles or standing water is one factor, and brake overheating caused by prolonged use or hard driving is another that can lead to failure. If total brake failure occurs, there are several corrective actions you can initiate. There is a requirement that every vehicle on the road in Delaware be in proper working order with functional equipment. In passenger vehicles, there are two main braking systems: a hydraulic four-wheel brake system, and a mechanically-operated rear wheel parking brake. All brakes and brake components should be maintained in good condition at all times. Properly maintained brakes are not only required by law, but they are essential for the safe operation of the motor vehicle. It is advisable to check out the condition of your vehicle's brakes periodically to ensure that they function properly. An emergency situation would involve a total failure of the brakes along with the vehicle gaining momentum and speed while heading downhill. Procedures to follow include:

1. Pumping Brakes - Oftentimes a brake line is clogged and brake fluid is not flowing properly. Pumping would attempt to distribute brake fluid adequately. Try this solution first.

NOTE: Do not pump Anti-Lock Brakes (ABS). To initiate ABS Brakes, you must fully compress the brake pedal to near maximum capacity. This will activate the computer to pulsate the brake pads automatically and will continue while pressure is held down.

When used properly, an antilock brake system (ABS) is a safe and effective braking system. ABS allows the driver to maintain directional stability, control oversteering, and in some situations, reduce stopping distances during emergency braking situations, particularly on wet and slippery road surfaces.

When your brakes lock up on wet and slippery roads or during a panic stop, you lose steering control and your vehicle can spin. Rear wheel ABS prevents wheel lockup so that your car stays in a straight line. If your car has ABS control on all four wheels, you also keep control of steering. If you have steering control, it is possible to avoid a crash by steering around hazards if a complete stop cannot be accomplished in time. ABS brakes should prevent your vehicle from skidding. Pulsation may be felt in the brake pedal and you may hear a clicking sound. This is not a sign of trouble but is an indication that your ABS brakes are at work.

The most important thing to remember is to not pump ABS brakes; just hold your foot firmly on the brake pedal and remember that you can still steer.

Types of Brakes

Drum Brakes

 

Drum brakes consist of a brake drum attached to the wheel, a wheel cylinder, brake shoes and brake return springs. Hydraulic pressure from the master cylinder causes the wheel cylinder to press the brake shoes against the brake drum. This creates friction between the shoes and drum to slow or stop your car. This basic design proved capable under most circumstances, but it had one major flaw. Under high braking conditions, like descending a steep hill with a heavy load or repeated high-speed slow downs, drum brakes would often fade and lose effectiveness. Usually this fading was the result of too much heat build-up within the drum. Remember that the principle of braking involves turning kinetic energy (wheel movement) into thermal energy (heat). For this reason, drum brakes can only operate as long as they can absorb the heat generated by slowing a vehicle's wheels. Once the brake components themselves become saturated with heat, they lose the ability to halt a vehicle, which can be somewhat disconcerting to the vehicle's operator.

Disc Brakes

Disc brakes consist of a disc brake rotor, which is attached to the wheel, and a caliper, which holds the disc brake pads. Hydraulic pressure from the master cylinder causes the caliper piston to clamp the disc brake rotor between the disc brake pads. This creates friction between the pads and rotor, causing your car to slow down or stop. Though disc brakes rely on the same basic principles to slow a vehicle (friction and heat), their design is far superior to that of drum brakes. But unlike drum brakes, which allow heat to build up inside the drum during heavy braking, the rotor used in disc brakes is fully exposed to outside air. This exposure works to constantly cool the rotor, greatly reducing its tendency to overheat or cause fading. Not surprisingly, it was under racing circumstances that the weaknesses of drum brakes and the strengths of disc brakes were first illustrated. Racers with disc brake systems could carry their speed "deeper" into a corner and apply greater braking force at the last possible second without overheating the components. Eventually, as with so many other automotive advances, this technology filtered down to the cars driven by everyday people on public roads.

2. Downshift - The goal with downshifting is to create more friction in the transmission. Shifting to a lower gear will create more tension in the transmission and slow down the vehicle. Downshifting would also be effective in an automatic transmission vehicle.

3. Apply Parking Brake - Your vehicle's parking brake can help to slow down your vehicle. Use of the parking brake should be a gradual application, with no dramatic movements. Drastic tugging of the brake may cause loss of vehicle control and overturning. (The parking brake in many vehicles is rarely used. Many drivers are under the false impression that a vehicle parked while still in gear is unlikely to roll. The parking brake, however, is in a motor vehicle for a reason. Car manufacturers can save countless thousands of dollars during vehicle production if they were to omit parking brakes. However, the value of the parking brake is immeasurable. A properly functioning parking brake should be used at all times in conjunction with a vehicle left in gear or in the parked position. The parking brake should be sufficient to hold the vehicle on any grade and capable of locking the wheels to limit any vehicle movement.) Your goal is to slow down the vehicle by any means and not lock up your wheels, as it may only cause more problems.


4. Attempt to Warn Others - When your vehicle's brakes are not functioning, you should honk the horn or make other efforts to notify other drivers out of fairness to them. An out-of-control vehicle is a hazard to all on the road.

5. Sideswipe Objects (attempting to reduce speed)- Sideswiping involves slowing down the vehicle by deflecting it off other objects on the road. No object should ever be hit head-on, nor should objects like curbs be hit, as they could cause the car to overturn. Guard rails and parked cars would be good objects to sideswipe, as they might gradually slow down the vehicle.

6. Shift into Reverse -Shifting into reverse will grind all the gears of the transmission together and will also slow down the vehicle. The transmission will be destroyed, but your life may be saved. This should only be done as a last resort after you have tried all other options.

NOTE: The vehicle should never be turned off in an attempt to stop.
This action will cause other car functions, such as steering, to also fail.

1. Left Front Tire - If the left front tire blows out, the car will pull to the left, and the steering will be quite heavy. Do not fight the pull, but instead grab hold of the steering wheel with both hands, gain control of the vehicle, and gradually slow down the vehicle. No dramatic or excessive braking should be attempted.

2. Right Front Tire - If the right front tire blows out, the car will pull to the right, and the steering will be quite heavy. Do not fight the pull, but instead grab hold of the steering wheel with both hands, gain control of the vehicle, and gradually slow down the vehicle. No dramatic or excessive braking should be attempted. At speeds below 55 mph, a blowout should be an easily controlled emergency.

3. Rear Tires - A blowout in any of the rear tires will cause the car to fishtail and feel unstable in the rear. Control of the steering wheel is vital, as is awareness of any other vehicles around. Slowing the car down gradually will help alleviate potential collisions.
 
 

C. Skids - An out-of-control skid is caused when the vehicle's tires lose contact with the road. Often, a thin layer of water gets between the tires and the road, and the vehicle begins to hydroplane. The old adage, "steer or turn into the skid," applies only if the driver knows the intended meaning. In a skid, the back wheels of the vehicle are the ones actually skidding, with the front tires following. Turn the steering wheel in the direction the back wheels are skidding, or in short, steer the vehicle in the intended direction. Some call it "counter" steering, while others simply call it "correcting" the skid. This description is appropriate as long as the wheels of the vehicle again grasp the road and find the pavement grooves. Commonly, drivers turn the steering wheel into the direction the vehicle is perceived to be skidding or the direction the front of the vehicle is headed. This will only add to the problem and send the car spiraling out of control. In a car with front wheel drive, the same actions should be taken, but some minor acceleration should be applied. Again, the attempt is to reacquaint the car's wheels with the pavement.

Special note on skids...

- Avoid turning or swerving suddenly

- Don't apply the brakes too quickly

- Pump the brakes and don't oversteer

- Keep the vehicle clutch engaged, and gradually remove your foot from the accelerator

- Pay special attention when driving on snow or ice

- Avoid driving on the shoulder of the road

- When traction is poor to begin with, drive in a higher gear and accelerate gradually

Collision Avoidance - Handling Emergencies

Prevention and avoidance is the best way to deal with a potential collision. Here are a few tips to practice:

• Be alert and well-rested.
• Always expect the unexpected. Never assume drivers will follow through on what they appear to be doing.
• Keep eyes moving (12-15 seconds or 1/4 mile ahead).
• Maintain 3-4 second following rule as needed.
• Look for potential hazards, poor road conditions, wrecks, etc.
• Seek out an escape route, if available.
• Check the vehicles behind you every 5-7 seconds.
• Adjust speed to suit conditions.
• Plan ahead.
• Honk your horn when appropriate (you are only allowed to use your horn to avoid or warn others of a potential collision).
• Watch out for trucks and buses.
• Watch out for pedestrians and bicyclists.
• Signal and announce your intentions.

Remember, practicing good vehicle maintenance can greatly reduce the chances of emergency situations on the road.

There are many factors which can distract you on the road. Identifying distractions and not allowing them to adversely affect the driving task are vital to collision prevention.

A. Driver Distractions (Inside the Vehicle) - Automobiles are often equipped with cellular phones, compact disc players, fax machines, etc., which distract the driver from the road. The driver must be made more aware of distractions affecting the ability to drive. Reaching for a ringing phone or searching for a radio station increases the potential for a collision.

Note on cell phones: It is illegal for anyone under the age of 18 with a Level 1 Learner's Permit or a Driver's Education Learner's Permit to use a cell phone, text messager or other similar device while driving, except in emergencies when stopped off the road.

This Act prohibits any minor with a Level 1 Learner's Permit or a Drivers' Education Learner's Permit from using a cell phone or similar devise while operating a motor vehicle. This prohibition does not apply during emergency situations where the permit holder has stopped the vehicle at a location off of the lanes of travel. For a violation of this Act, young drivers are subject to the same penalties they would face if they were found to be a reckless or negligent driver of a motor vehicle or to have committed a serious moving traffic violation (i.e. at least a 1 month suspension for a first offense or 3 month suspension for a subsequent offense).

An article in the Los Angeles Times (February 13, 1997) cites a report by Canadian scientists which claims that talking on a cellular phone while driving quadruples the risk of having a crash, making it as dangerous as driving while drunk. A 2002-2005 study from the Insurance Institute for Highway Safety shows that even a hands-free phone does not reduce the risk of a crash. The safest option is to avoid using your cellular phone while operating a motor vehicle. However, if you still choose to use your phone, please follow the safety tips below:

1. Keep the phone close to you so you won't have to reach or look for it while driving.

2. Dial only when at a stoplight or sign, or pull off the road to dial.

3. Never use your phone in distracting traffic situations or in stop-and-go traffic. Pull over and use the phone while off the road.

4. Disconnect your cellular phone while using jumper cables as the power surge could burn out your phone battery.

5. If you have a phone in your car, use it to report emergencies on the road by dialing 911. Always be ready to provide the closest major cross streets or off-ramps in the area. NOTE: Cellular phone users in the United States make nearly 50,000 calls each day to report highway and neighborhood emergencies.

B. Driver Distractions (Outside the Vehicle) - Be aware of road hazards and road conditions that may affect the vehicle, but do not let outside distractions affect your safe driving habits. Billboards, homes, pedestrians, etc., may be attractive to view, but they should not deter you from the driving task. An awareness of the road is vital, because a wandering eye can prove deadly. For example, real estate brokers are statistically involved in more collisions, because the very act of looking at street names and addresses removes their eyes from the road. Without full attention to the roadways, collisions become inevitable. A handsome man or a pretty woman that distracts drivers often leads to rear-enders, exemplifying the need for the eyes to remain fixed on the road and concentrated on the task of driving. Emergency vehicles are another type of outside distraction that require respect and cannot affect you adversely. Ambulances or fire trucks should be allowed to use the roadway, unencumbered by other vehicles, and should not be obstructed in any way. Staring at or following emergency vehicles will only add to the problem on the road. In addition, do not get caught up in scenery by staring at homes, buildings or views. These distractions will only contribute to potential collisions.

C. Children/Other Passengers - Your focus should always be on the road. Passengers, particularly children, often create distractions for drivers and decrease road awareness. All passengers must be buckled in the vehicle and be instructed to minimize any distraction for the driver. Children, in particular, will take away your attention and heighten your potential for a collision.

D. Pets - Pets should be leashed while in the vehicle, particularly if they are in the back of an open truck. Pets on the laps of drivers can cause collisions, as they block the usage of car functions. If traveling with a pet, never let it conflict with your control of the vehicle.

E. Eating - Eating is a distraction that forces you to take your hands off the steering wheel and your eyes off the road. If you eat, you should do so prior to driving, but if this is not possible, eat only on the side of the road in a parked car.

F. Drinking - Drinking and subsequent spills often cause the eyes to focus away from the road. Hot spills can result in burns and increase the chances for a collision as well.

G. Smoking - Smoking prevents you from keeping both hands on the steering wheel, while burns and ashes can result in lack of focus on the road.

H. Radio, Audio/Video Tapes, CDs, DVDs - Finding a station and looking down at the radio takes your eyes away from the road. Leaning over to change the station or an audio tape/CD often causes the vehicle to veer off course and increases the potential for getting into a collision. Have your favorite stations preset on your radio so you do not have to tune it to look for what you want. Locating a station should never adversely affect your driving. Additionally, some people combine driving with dancing. Music is often stimulating, yet physical gyrations while driving can interfere and prove to be unsafe. Never watch a video or DVD while driving. While this may seem obvious, you'd be surprised at how many people do it! Keep your eyes on the road, not on a video screen.

I. Reading - Attempting to read and drive at the same time is impossible. The act of driving should be respected. Reading often leads to rear-end collisions, as eyes are not focused on the road and the driver does not see cars braking ahead. Reading newspapers or books perched on your steering wheel is simply asking for trouble.

J. Applying Makeup / Shaving - These actions have no place in the vehicle whatsoever. Prepare yourself at home before driving. It is common to see men shaving or women applying lipstick or makeup while behind the wheel. Again, you cannot combine driving with these actions. A collision is likely to occur.

K. General Distractions - Awareness of the immediate surroundings while driving is essential to avoiding collisions. Distractions such as buildings, people, or other vehicles must not alter your vehicle control. You should alter your visual habits if they are not conducive for the safe operation of a motor vehicle. Wandering eyes will heighten collision potential. Keep your eyes busy by training them to look every two or three seconds at the rear view mirror, the speedometer, and the road ahead so you can get an adequate determination of speed, positioning and road conditions. Remember: Be prepared for the unexpected.

Special Note: On January 10th, 2001, Ford Motor Corporation opened a $10 million driving simulator laboratory called VIRTTEX, or VIRtual Test Track EXperiment, which allowed their researchers to test new product features and study driver behaviors safely in a controlled environment. This was the first automotive lab to feature a full-scale driving simulator that tracks drivers’ eye movements while they engaged in various driving behaviors, such as using onboard gadgets and trying to maneuver curves on simulated highways. Ford released results from their first test the following year that supported the findings of previous studies regarding cellular telephones.

General Driving Tips

• Always keep ample following distance, and drive at a safe speed. Allowing a space cushion between your car and the one you immediately follow allows more time to avoid unforeseen actions (i.e., turns and stops).
• Be cautious when making right and left turns.
• Try to anticipate the movements of other drivers.
• Change lanes only when visibility permits.
• Intersections should be entered with extreme caution. Never rely entirely on traffic signals.
• Always know your position on the road.