Messing with driving instructors, Part 2

S.I.P.D.E. including distance guidelines and adaptation to surroundings

Safe driving depends, to a great extent, upon your ability to correctly analyze a traffic situation around you and to react to it. Good seeing habits are most important for responsible driving. However, just being able to see well is no guarantee you will see all critical clues or make correct responses. The driving task is primarily a thinking task. Driving is about 10 percent physical and 90 percent mental. Physically, all you can do is start, stop and turn your car. All the rest is mental. Most responsible drivers use some kind of system that deals with most of the traffic possibilities they will encounter. These drivers have fewer close calls and collisions than drivers who do not use an organized system.

The S.I.P.D.E. process is an organized system of seeing, thinking and responding.

1. Search
2. Identify
3. Predict
4. Decide
5. Execute

SEARCH

You begin by searching the traffic situation to gather information for your decisions and actions. You need to develop a system of searching for information and clues within and about the driving environment to recognize possible problems ahead, behind and on both sides of your car. Your must process this information properly and then decide how to avoid conflict and you must execute the correct actions.

You need to develop a visual search pattern. A visual search pattern is a process of searching critical areas in a regular sequence. To use a visual search pattern, look for clues in a certain pattern and in a systematic manner.

An example of a visual search for driving straight ahead is:

1. Glance ahead.
2. Check your rearview mirror.
3. Glance ahead again.
4. Glance at the side of the roadway or intersection.
5. Glance ahead again.
6. Check your speedometer and gauge.
7. Glance ahead again.

All glances should last only an instant.

Different driving environments and traffic situations present a variety of visual search problems. Mr. Harold Smith introduced a system for safe driving many years ago. The Smith System stresses eye discipline and the idea of space cushion.

1. Aim high steering:
   To "aim high" means to look far ahead when you drive. We do not look at our feet when we walk, we look ahead. Aiming high allows you to be able to analyze traffic situations. In city traffic, look at least one block ahead. On highways and expressways, look as far ahead as possible, for at least 2-3 seconds.
2. Keep your eyes moving:
   Glancing near and far, right and left, in mirrors as well as the instrument panel. Be sure to look ahead again.
3. Get the big picture:
   Getting the big picture is the mental process of putting together the critical clues that your eyes selected and identified as they scanned.
4. Make sure others see you:
   This rule tells you to communicate with other drivers. You can communicate your presence or intentions with lights, horn, car position, eye contact or body movement.
5. Leave yourself an out.
   Leaving yourself an out means you have identified an escape path in case of a possible conflict. You constantly adjust position to keep space around your vehicle in changing traffic conditions. If you do not have at least one available out, adjust your position until you do have one.

IDENTIFY

If you do not know what you are looking for, knowing how, when, and where to look does little good. Identify specific driving related clues.

Identify parked cars on a street, such as front wheels turned towards the street which could be an indication of a motorist possibly pulling into your lane. Vapor coming from an exhaust pipe or a driver sitting in the car. These clues indicate that a parked car may be ready to enter your path of travel.

The kinds of clues you search for will change in different driving environments. In city driving, search for intersections, pedestrians and other traffic. On open highways, search areas much further ahead. Look for crossroads, slow moving vehicles, and animals. During expressway driving, search the other lanes ahead, behind, and beside you.

Identify other users by searching the traffic scene for other roadway users which might affect your planned path of travel.

Develop the habit of ground identification. Ground viewing is when you make quick glances at the roadway in front of your vehicle.

Always be on the lookout to identify problem drivers. Problem drivers usually give clues by their driving behavior. Some fast drivers may be problem drivers. They may try to pass without enough room or in a no passing zone. They frequently change lanes, trying to get ahead of the normal traffic flow. Distracted or confused drivers may also be problem drivers. Be alert for those who are driving with only one hand on the steering wheel while holding a coffee cup or a telephone in the other hand.

The roadway itself is another important area to watch. Identify intersections, hills and curves early. Be aware ahead of time that the width of your lane may be reduced. Multi-lane roadways often narrow into single lane roadways. Identify signs warning you of this change early enough to position your car in the through lane. Always try to avoid making any unnecessary stops in moving traffic.

Identify changes in the width of lanes, such as standing water, potholes or objects in the roadway that can narrow your lane space. Identify these conditions early so that you have more time to plan a path around them.

Your identification process should keep you looking constantly for roadside hazards such as pedestrians, bicyclists, parked cars and animals. Watch for shopping center entrances, roadside stands, and restaurants.

Identify the roadway surface and conditions each time you begin to drive. Many times, the weather will change while you are driving. Roadway surfaces may be dry when you start out and then become wet and slippery with rain.

Identify traffic controls as early as possible so you are ready to make correct responses.

PREDICT

Once you have identified a possible hazard, predict how this hazard might create a conflict. When you predict, you interpret the information you have identified. You predict where possible points of conflict can occur. You try to foresee what might happen and how it might affect your path.

Analyzing a situation is part of predicting. It is also a basic part of responsible driving. Most of the time you will be faced with more than one possible hazard, so predicting can become a complex problem.

Predicting involves what is happening, what could happen and, if it does happen, how it might affect you. To predict, you must evaluate the situation and make a judgment about the possible consequences. The more complex a situation is, the more difficult it is to identify and predict.

Making a judgment about a traffic situation involves measuring, comparing, and evaluating. As you drive, you judge speed, time, space, distance, traction and visibility. You make judgments about your own driving performance as well as the action and performance of other drivers.

When predicting the actions of others, you do not want to assume that other roadway users will always take the correct action. Instead watch for clues to what they might do. The responsible driver predicts that other drivers and pedestrians will make mistakes.

The most important types of predictions to make concerning the actions of other drivers are: Where will the other driver go? What actions will the other driver take? Is more than one action possible? When will the action be taken? Where might I be when that action happens? Where might our paths cross?

You should also attempt to predict that pedestrians may step out in front of you. By making these predictions, you will be able to slow, or stop in order to avoid a conflict.

Always be prepared to adjust your speed for varying conditions and situations. Different traffic, roadway, and weather conditions can change the amount of time and space needed for slowing down and braking control.

DECIDE

Once you have identified a situation and predicted a possible conflict, you must then decide upon an action to avoid the conflict. There is probably no task more important for a driver than making wise decisions in time to avoid conflict. There may be times when you fail to identify every clue in a situation. Other users will often take actions you did not predict. The decisions you make in these situations become the basic factors for your safe driving. Be prepared to change your plans to avoid a conflict.

Any decision you make will be influenced by your own speed and the speed of other vehicles. Many drivers think that slowing down is the only way to avoid a conflict. It is not. It may also require a quick maneuver.

You can decide to change your position on the roadway or you might change lanes to the left or right. The Smith System guidelines of "leave yourself an out" allow you to change directions when necessary. You will then have an escape path to use in order to avoid conflict. Having an escape path gives you space all around your vehicle.

The decision to communicate with others helps reduce a possible conflict. The Smith System Rule, "make sure others see you," tells others where you are and what you plan to do.

You may use your lights to give signals to other drivers. Use your brake lights to signal the other drivers that you intend to slow or stop. Using your turn signals tells the other drivers that you plan to turn or change lanes. Your emergency flashers convey the message I am in trouble or I cannot move. Remember that four way emergency flashing lights on a moving vehicle is a violation of Florida Law. White back up lights let others know that you are backing up or intend to back up. Look for back up lights on cars in parking lots as a clue for a possible conflict. Parking lights warn other drivers that you are parked along the side of the roadway. Try to develop eye contact with other drivers. You can communicate many messages this way. If there is a possibility of conflict, check to see if the other person is looking at you. While eye contact often helps reduce the risk of conflict it does not guarantee that there will not be conflict.

EXECUTE

Carrying out your decisions in order to avoid conflict is the "execute" step in the S.I.P.D.E. process. This step involves the physical skills used in driving. In most cases you will execute routine maneuvers and actions.

Executing the decision to accelerate means you have judged the speed and use of space by others. You might accelerate to get out of another driver's way or to avoid an obstruction in the roadway. Remember that different vehicles have different acceleration capabilities. Consider your own vehicle's capabilities before executing a decision to accelerate.

When you have decided to decelerate or brake to reduce risk, you should have already considered the surface of the roadway. The amount of braking needed will vary with the speed of your car and the condition of the roadway. When braking suddenly, check vehicles to the rear. Avoid locking the brakes during an emergency stop. Locked brakes make steering impossible, since wheels must be turning to provide traction for steering.

When you decide to steer away from a conflict, execute just the amount of steering needed. Over steering can cause you to lose control of your vehicle, especially at higher speeds. Higher speeds also require more space for your maneuver.

You will often need to execute a combination of actions. Sometimes you might need to accelerate and steer at the same time. In other situations you might need to brake, communicate, and steer at the same time. The precision and timing with which you execute these actions determines whether or not a conflict will occur.¹

Following distance including two-second minimum, when to increase speed and dealing with tailgaters

FOLLOWING TOO CLOSE

Being too close is only a good thing in horseshoes and drive-in movies, not in traffic.

The concept of one car length for every ten miles per hour has been rendered obsolete by NHTSA (National Highway Traffic Safety Administration) research. The primary reasoning for this is people have difficulty judging what one car length is consistently. Furthermore, at fifty-five miles per hour, a vehicle travels 80.63 feet in one second (55 mph multiplied by 1.466 conversion factor equals 80.63 feet per second). If the driver has accurately judged fifty-five feet of distance behind the car and has to stop. In the three-quarters of a second reaction time, the car will travel 60.47 feet before the driver can even begin to apply the brakes, all but assuring a collision. If you maintain a minimum (for clear, dry weather) of a two-second interval between you and the car ahead, at fifty-five mph you will have a 161.3- foot buffer ahead to react and stop within.

When you are following another vehicle in your lane, you should want to be in the two-second cushion. Pick out a stationary object ahead of the car in front of you. That may be a white line across the road, a shadow of an overpass, or a parked car on the shoulder. Pick out something that enables you to start counting when the lead vehicle passes that spot. One-thousand one, one-thousand two, if you are not at the spot that the car ahead of you was when you started counting, then you are a reasonable distance behind him. If you have passed that spot before you say "one-thousand two" you are too close. Now what do you do? You can take your foot off the gas and slow down until you are a safe distance or you may change lanes if it is safe.

Now, there are times that two seconds is not enough. The two-second rule is a minimum. Additional seconds need to be added for darkness, bad weather, towing, vehicles following too closely, etc. This is in the short or close range environment scanning for immediate hazards. Drivers should also be looking at least 10 seconds ahead of their vehicles to become aware of the medium distance potential hazards. You need to always try to keep a safe area around you. Keep from getting boxed in and not having a way out if someone presents a hazard. The law does not leave any good reason for hitting another vehicle in the rear. F.S. 316.0895 (1) "The driver of a motor vehicle shall not follow another vehicle more closely than is reasonable and prudent, having the regard for the speed of such vehicles and the traffic upon, and the conditions of, the highway."²

Stopping distance in relationship to speed

We must accept the fact that the faster we go, the further it will take us to stop. Several things must be considered to determine the stopping distance.

The above graph indicates the reaction (red) and braking (gold) distance for the total braking distance at various speeds.

Your mental and physical condition is very important.

Of course, age, use of drugs, and physical fatigue will all affect your ability to react to a potential hazard, sometimes called perception and reaction time. Reaction time in daily driving can be as high as 1.5 seconds with various driving distractions.

The vehicle is another important factor to be considered in the stopping distance. Vehicles must have brakes that meet certain standards. We have even developed alternative braking systems such as Anti-locking Braking Systems (ABS).

The road and weather conditions all must be considered. As we discussed in another section of the manual, friction is the most important factor in stopping a vehicle.

When you are forced to stop, three things must happen. You must perceive the hazard or warning; react; and use your brakes to stop.

The length of time you take to identify, predict, and decide to slow for a hazard is called your perception time. You cannot consistently estimate your perception time because your ability to perceive will change from time to time. By scanning and maintaining the proper spacing method that we discussed earlier, you allow yourself more reaction time.

Once you know a hazard will be a problem, the length of time you take to execute your actions is your reaction time. An average driver's reaction time is ¾ of a second, in clinical laboratory settings. If you are impaired due to alcohol, drugs or fatigue, your reaction time will increase; thus the time to stop and distance that your car travels will also increase.

The distance your vehicle travels from the time you apply the brakes until your vehicle stops is called braking distance. These distances will change depending on your ability at the time, your vehicle conditions, and the conditions of the road. Estimating stopping distance can be hard so it is always better to utilize the two second rule. This rule enables you to project your approximate stopping distance under ideal conditions at any speed.

Don't forget, the higher the speed, the longer the braking distance. At higher speeds, you will have a harder time controlling your vehicle. A vehicle with worn tires or bad brakes needs a longer distance to stop. If the brakes on one side of your car are worn or out of adjustment, your vehicle will pull to one side in a stop. If you panic and slam on your brakes you might lose control of your car in an emergency situation. Remember wet road surfaces will reduce traction on the road and increase your braking distance.

Environmental hazards, rain, slick roads, standing water and fog

We drive in environmental conditions each time we make a trip. Understanding better how to handle changing conditions will make the trip more enjoyable and safer. Dealing with too much light, such as the sun in your eyes, may be handled by wearing good sunglasses or properly using the sun visor. Remember always have the lower edge of the sun visor pushed toward the windshield.

Night driving brings on adjustments that you must deal with successfully. Aside from reducing detail, darkness conceals hazards: pedestrians, bicycles, stalled cars, curves and other objects or conditions. You must make a decision on the basis of a sketchy and incomplete picture. It is more difficult to judge the speed and position of other vehicles. You must depend largely on your headlights, which will show only a relatively short and narrow path ahead. It does not bend around corners. Usually, adequate highway lighting is limited. Glare from roadside lighting and the headlights of on-coming vehicles may impair your visibility. Keep your panel lights dim for better vision, but always have enough panel light to read your speedometer and other gauges. Reduce speed so that you can stop within the visible distance. Increase seeing distance by keeping the headlights clean and properly aimed and the windshield clean.

There are other visibility conditions we must consider to drive safe, such as fog, haze, smoke and mist that can affect our visibility greatly. Remember, Florida law requires that we turn on our low beam headlights and use our windshield wipers under such conditions. Never drive with only parking lights on. Be alert for slow moving and or stopped traffic. Check your rearview mirrors frequently for vehicles that are approaching quickly from the rear. Be especially careful for patches of fog in valleys and low-lying areas. If possible, drive slowly but keep moving. But if conditions are too bad, pull over as far to the right, off the main travel portion of the roadway as possible and stop. Leave your parking lights on and activate your hazard lights.

Driving in the rain is a hazard that we must consider. During rainy conditions when the roads are wet, we must realize our stopping distance is increased. When braking, friction between your tires and the surface of the roadway affect your stopping distance. Wet roads have less friction and increase the distance it takes you to stop. Driving through water may cause hydroplaning. The purpose of the tread on a tire is to prevent hydroplaning from happening; that is why the law requires tire treads to meet certain standards. As little as 1/16 of an inch of water can cause hydroplaning.

Hydroplaning occurs when your tires ride on a thin layer of water and do not touch the road. When the car is riding on a film of water there is no friction between your tires and the road. Hydroplaning also affects our ability to steer and brake.

Do not drive through large bodies of standing water as it can affect brake performance, the vehicle's electrical system, and cause engine failure which could result in costly repairs. If the standing water is concentrated on one portion of the road and only one side of the vehicle goes through the water the vehicle will tend to pull in that direction. The force of the pull is dependent on the depth of the water and the speed of the vehicle.

Simply put, remember, as you approach the standing water, a good habit to get into may be lifting your foot off the gas pedal and to check your rearview mirror for vehicles that may be following you too closely.

Remember:

1. Slow down before hitting the water.
2. Turn wipers on before hitting the water.
3. Tap brakes as you exit.
4. Use caution in checking outside mirrors. Rain can distort or obliterate images.
5. Do not drive through standing water if you do not know how deep it is.

Wind can also become a problem, especially when driving large vehicles, such as a truck or a motor home. Be alert for cross gusts when leaving overpasses, large buildings or other large areas where the wind is being blocked from striking your vehicle.

An ongoing problem with wind gusts is when you are being passed by large vehicles such as tractor trailers or buses traveling in the same direction. As you are traveling wind gusts from these vehicles can make your car more difficult to control. As these vehicles start to pass you, grip your steering wheel firmly. You may also want to reduce your speed a little.

Environmental Causes

Florida Traffic Crash Facts – 2004
Lighting Conditions at the Time of Crash

Lighting Conditions	All Crashes	Fatal Crashes	Injury Crashes	Property Damage
Daylight	161,487	1,290	97,669	62,528
Dusk	7,010	75	3,949	2,986
Dawn	3,344	60	1,897	1,387
Darkness	76,636	1,498	37,867	37,271
Unknown	4,425	13	1,006	3,406
Total	252,902	2,936	142,388	107,578

Road Surface Conditions at the Time of Crash³

Surface Conditions	All Crashes	Fatal Crashes	Injury Crashes	Property Damage
Dry	215,862	2,618	121,684	91,560
Wet	32,087	298	18,641	13,148
Slippery	1,383	5	885	493
Icy	67	2	32	33
Other	3,503	13	1,146	2,344
Total	252,902	2,936	142,388	107,578