Seeing, Communicating & Controlling Speed
To be a safe driver you need to know what’s going on all around your vehicle. Not looking properly is a major cause of accidents.
2.4.1 – Seeing Ahead
All drivers look ahead; but many don’t look far enough ahead.
Importance of Looking Far Enough Ahead. Because stopping or changing lanes can take a lot of distance, knowing what the traffic is doing on all sides of you is very important. You need to look well ahead to make sure you have room to make these moves safely.
How Far Ahead to Look. Most good drivers look at least 12 to 15 seconds ahead. That means looking ahead the distance you will travel in 12 to 15 seconds. At lower speeds, that’s about one block. At highway speeds it’s about a quarter of a mile. If you’re not looking that far ahead, you may have to stop too quickly or make quick lane changes. Looking 12 to 15 seconds ahead doesn’t mean not paying attention to things that are closer. Good drivers shift their attention back and forth, near and far. Figure 2.6 illustrates how far to look ahead.
Look for Traffic. Look for vehicles coming onto the highway, into your lane, or turning. Watch for brake lights from slowing vehicles. By seeing these things far enough ahead, you can change your speed, or change lanes if necessary to avoid a problem. If a traffic light has been green for a long time it will probably change before you get there. Start slowing down and be ready to stop.
2.4.2 – Seeing to the Sides and Rear
It’s important to know what’s going on behind and to the sides. Check your mirrors regularly. Check more often in special situations.
Mirror Adjustment. Mirror adjustment should be checked prior to the start of any trip and can only be checked accurately when the trailer(s) are straight. You should check and adjust each mirror to show some part of the vehicle. This will give you a reference point for judging the position of the other images.
Regular Checks. You need to make regular checks of your mirrors to be aware of traffic and to check your vehicle.
Traffic. Check your mirrors for vehicles on either side and in back of you. In an emergency, you may need to know whether you can make a quick lane change. Use your mirrors to spot overtaking vehicles. There are “blind spots” that your mirrors cannot show you. Check your mirrors regularly to know where other vehicles are around you, and to see if they move into your blind spots.
Check Your Vehicle. Use the mirrors to keep an eye on your tires. It’s one way to spot a tire fire. If you’re carrying open cargo, you can use the mirrors to check it. Look for loose straps, ropes, or chains. Watch for a flapping or ballooning tarp.
Special Situations. Special situations require more than regular mirror checks. These are lane changes, turns, merges, and tight maneuvers.
Lane Changes. You need to check your mirrors to make sure no one is alongside you or about to pass you. Check your mirrors:
- Before you change lanes to make sure there is enough room.
- After you have signaled, to check that no one has moved into your blind spot.
- Right after you start the lane change, to double-check that your path is clear.
- After you complete the lane change.
Turns. In turns, check your mirrors to make sure the rear of your vehicle will not hit anything.
Merges. When merging, use your mirrors to make sure the gap in traffic is large enough for you to enter safely.
Tight Maneuvers. Any time you are driving in close quarters, check your mirrors often. Make sure you have enough clearance.
How to Use Mirrors. Use mirrors correctly by checking them quickly and understanding what you see.
- When you use your mirrors while driving on the road, check quickly. Look back and forth between the mirrors and the road ahead. Don’t focus on the mirrors for too long. Otherwise, you will travel quite a distance without knowing what’s happening ahead.
- Many large vehicles have curved (convex, “fisheye,” “spot,” “bugeye”) mirrors that show a wider area than flat mirrors. This is often helpful. But everything appears smaller in a convex mirror than it would if you were looking at it directly. Things also seem farther away than they really are. It’s important to realize this and to allow for it. Figure 2.7 shows the field of vision using a convex mirror.
2.5 – Communicating
2.5.1 – Signal Your Intentions
Other drivers can’t know what you are going to do until you tell them.
Signaling what you intend to do is important for safety. Here are some general rules for signaling.
Turns. There are three good rules for using turn signals:
- Signal early. Signal well before you turn. It is the best way to keep others from trying to pass you.
- Signal continuously. You need both hands on the wheel to turn safely. Don’t cancel the signal until you have completed the turn.
- Cancel your signal. Don’t forget to turn off your turn signal after you’ve turned (if you don’t have self-canceling signals).
Lane Changes. Put your turn signal on before changing lanes. Change lanes slowly and smoothly. That way a driver you didn’t see may have a chance to honk his/her horn, or avoid your vehicle.
Slowing Down. Warn drivers behind you when you see you’ll need to slow down. A few light taps on the brake pedal — enough to flash the brake lights — should warn following drivers. Use the four-way emergency flashers for times when you are driving very slowly or are stopped. Warn other drivers in any of the following situations:
Trouble Ahead. The size of your vehicle may make it hard for drivers behind you to see hazards ahead. If you see a hazard that will require slowing down, warn the drivers behind by flashing your brake lights.
Tight Turns. Most car drivers don’t know how slowly you have to go to make a tight turn in a large vehicle. Give drivers behind you warning by braking early and slowing gradually.
Stopping on the Road. Truck and bus drivers sometimes stop in the roadway to unload cargo or passengers, or to stop at a railroad crossing. Warn following drivers by flashing your brake lights. Don’t stop suddenly.
Driving Slowly. Drivers often do not realize how fast they are catching up to a slow vehicle until they are very close. If you must drive slowly, alert following drivers by turning on your emergency flashers if it is legal. (Laws regarding the use of flashers differ from one state to another. Check the laws of the states where you will drive.)
Don’t Direct Traffic. Some drivers try to help out others by signaling when it is safe to pass. You should not do this. You could cause an accident. You could be blamed and it could cost you many thousands of dollars.
2.5.2 – Communicating Your Presence
Other drivers may not notice your vehicle even when it’s in plain sight. To help prevent accidents, let them know you’re there.
When Passing. Whenever you are about to pass a vehicle, pedestrian, or bicyclist, assume they don’t see you. They could suddenly move in front of you. When it is legal, tap the horn lightly or, at night, flash your lights from low to high beam and back. And, drive carefully enough to avoid a crash even if they don’t see or hear you.
When It’s Hard to See. At dawn, dusk, in rain, or snow, you need to make yourself easier to see. If you are having trouble seeing other vehicles, other drivers will have trouble seeing you. Turn on your lights. Use the headlights, not just the identification or clearance lights. Use the low beams; high beams can bother people in the daytime as well as at night.
When Parked at the Side of the Road. When you pull off the road and stop, be sure to turn on the four-way emergency flashers. This is important at night. Don’t trust the taillights to give warning. Drivers have crashed into the rear of a parked vehicle because they thought it was moving normally.
If you must stop on a road or the shoulder of any road, you must put out your emergency warning devices within ten minutes. Place your warning devices at the following locations:
- If you must stop on or by a one-way or divided highway, place warning devices 10 feet, 100 feet, and 200 feet toward the approaching traffic. See Figure 2.8.
- If you stop on a two-lane road carrying traffic in both directions or on an undivided highway, place warning devices within 10 feet of the front or rear corners to mark the location of the vehicle and 100 feet behind and ahead of the vehicle, on the shoulder or in the lane you stopped in. See Figure 2.9.
Back beyond any hill, curve, or other obstruction that prevents other drivers from seeing the vehicle within 500 feet. If line of sight view is obstructed due to hill or curve, move the rear-most triangle to a point back down the road so warning is provided. See Figure 2.10.
When putting out the triangles, hold them between yourself and the oncoming traffic for your own safety. (So other drivers can see you.)
Use Your Horn When Needed. Your horn can let others know you’re there. It can help to avoid a crash. Use your horn when needed. However, it can startle others and could be dangerous when used unnecessarily.
2.6 – Controlling Speed
Driving too fast is a major cause of fatal crashes. You must adjust your speed depending on driving conditions. These include traction, curves, visibility, traffic and hills.
2.6.1 – Stopping Distance
Perception Distance + Reaction Distance +
Braking Distance = Total Stopping Distance
Perception distance. The distance your vehicle travels, in ideal conditions; from the time your eyes see a hazard until your brain recognizes it. Keep in mind certain mental and physical conditions can affect your perception distance. It can be affected greatly depending on visibility and the hazard itself. The average perception time for an alert driver is 1¾ seconds. At 55 mph this accounts for 142 feet traveled.
Reaction distance. The distance you will continue to travel, in ideal conditions; before you physically hit the brakes, in response to a hazard seen ahead. The average driver has a reaction time of ¾ second to 1 second. At 55 mph this accounts for 61 feet traveled.
Braking distance. The distance your vehicle will travel, in ideal conditions; while you are braking. At 55 mph on dry pavement with good brakes, it can take about 216 feet.
Total stopping distance. The total minimum distance your vehicle has traveled, in ideal conditions; with everything considered, including perception distance, reaction distance and braking distance, until you can bring your vehicle to a complete stop. At 55 mph, your vehicle will travel a minimum of 419 feet. See Figure 2.11.
The Effect of Speed on Stopping Distance. The faster you drive, the greater the impact or striking power of your vehicle. When you double your speed from 20 to 40 mph the impact is 4 times greater. The braking distance is also 4 times longer. Triple the speed from 20 to 60 mph and the impact and braking distance is 9 times greater. At 60 mph, your stopping distance is greater than the length of a football field. Increase the speed to 80 mph and the impact and braking distance are 16 times greater than at 20 mph. High speeds greatly increase the severity of crashes and stopping distances. By slowing down, you can reduce braking distance.
The Effect of Vehicle Weight on Stopping Distance. The heavier the vehicle, the more work the brakes must do to stop it, and the more heat they absorb. But the brakes, tires, springs, and shock absorbers on heavy vehicles are designed to work best when the vehicle is fully loaded. Empty trucks require greater stopping distances because an empty vehicle has less traction.
2.6.2 – Matching Speed to the Road Surface
You can’t steer or brake a vehicle unless you have traction. Traction is friction between the tires and the road. There are some road conditions that reduce traction and call for lower speeds.
Slippery Surfaces. It will take longer to stop, and it will be harder to turn without skidding, when the road is slippery. Wet roads can double stopping distance. You must drive slower to be able to stop in the same distance as on a dry road. Reduce speed by about one-third (e.g., slow from 55 to about 35 mph) on a wet road. On packed snow, reduce speed by a half, or more. If the surface is icy, reduce speed to a crawl and stop driving as soon as you can safely do so.
Identifying Slippery Surfaces. Sometimes it’s hard to know if the road is slippery. Here are some signs of slippery roads:
- Shaded Areas. Shady parts of the road will remain icy and slippery long after open areas have melted.
- Bridges. When the temperature drops, bridges will freeze before the road will. Be especially careful when the temperature is close to 32 degrees Fahrenheit.
- Melting Ice. Slight melting will make ice wet. Wet ice is much more slippery than ice that is not wet.
- Black Ice. Black ice is a thin layer that is clear enough that you can see the road underneath it. It makes the road look wet. Any time the temperature is below freezing and the road looks wet, watch out for black ice.
- Vehicle Icing. An easy way to check for ice is to open the window and feel the front of the mirror, mirror support, or antenna. If there’s ice on these, the road surface is probably starting to ice up.
- Just After Rain Begins. Right after it starts to rain, the water mixes with oil left on the road by vehicles. This makes the road very slippery. If the rain continues, it will wash the oil away.
- Hydroplaning. In some weather, water or slush collects on the road. When this happens, your vehicle can hydroplane. It’s like water skiing–the tires lose their contact with the road and have little or no traction. You may not be able to steer or brake. You can regain control by releasing the accelerator and pushing in the clutch. This will slow your vehicle and let the wheels turn freely. If the vehicle is hydroplaning, do not use the brakes to slow down. If the drive wheels start to skid, push in the clutch to let them turn freely.
It does not take a lot of water to cause hydroplaning. Hydroplaning can occur at speeds as low as 30 mph if there is a lot of water. Hydroplaning is more likely if tire pressure is low, or the tread is worn. (The grooves in a tire carry away the water; if they aren’t deep, they don’t work well.)
Road surfaces where water can collect can create conditions that cause a vehicle to hydroplane. Watch for clear reflections, tire splashes, and raindrops on the road. These are indications of standing water.
2.6.3 – Speed and Curves
Drivers must adjust their speed for curves in the road. If you take a curve too fast, two things can happen. The tires can lose their traction and continue straight ahead, so you skid off the road. Or, the tires may keep their traction and the vehicle rolls over. Tests have shown that trucks with a high center of gravity can roll over at the posted speed limit for a curve. Slow to a safe speed before you enter a curve. Braking in a curve is dangerous because it is easier to lock the wheels and cause a skid. Slow down as needed. Don’t ever exceed the posted speed limit for the curve. Be in a gear that will let you accelerate slightly in the curve. This will help you keep control.
2.6.4 – Speed and Distance Ahead
You should always be able to stop within the distance you can see ahead. Fog, rain, or other conditions may require that you slow down to be able to stop in the distance you can see. At night, you can’t see as far with low beams as you can with high beams. When you must use low beams, slow down.
2.6.5 – Speed and Traffic Flow
When you’re driving in heavy traffic, the safest speed is the speed of other vehicles. Vehicles going the same direction at the same speed are not likely to run into one another. In many states, speed limits are lower for trucks and buses than for cars. It can vary as much as 15 mph. Use extra caution when you change lanes or pass on these roadways. Drive at the speed of the traffic, if you can without going at an illegal or unsafe speed. Keep a safe following distance.
The main reason drivers exceed speed limits is to save time. But, anyone trying to drive faster than the speed of traffic will not be able to save much time. The risks involved are not worth it. If you go faster than the speed of other traffic, you’ll have to keep passing other vehicles. This increases the chance of a crash, and it is more tiring. Fatigue increases the chance of a crash. Going with the flow of traffic is safer and easier.
2.6.6 – Speed on Downgrades
Your vehicle’s speed will increase on downgrades because of gravity. Your most important objective is to select and maintain a speed that is not too fast for the:
- Total weight of the vehicle and cargo.
- Length of the grade.
- Steepness of the grade.
- Road conditions.
If a speed limit is posted, or there is a sign indicating “Maximum Safe Speed,” never exceed the speed shown. Also, look for and heed warning signs indicating the length and steepness of the grade. You must use the braking effect of the engine as the principal way of controlling your speed on downgrades. The braking effect of the engine is greatest when it is near the governed rpms and the transmission is in the lower gears. Save your brakes so you will be able to slow or stop as required by road and traffic conditions. Shift your transmission to a low gear before starting down the grade and use the proper braking techniques. Please read carefully the section on going down long, steep downgrades safely in “Mountain Driving.”
2.6.7 – Roadway Work Zones
Speeding traffic is the number one cause of injury and death in roadway work zones. Observe the posted speed limits at all times when approaching and driving through a work zone. Watch your speedometer, and don’t allow your speed to creep up as you drive through long sections of road construction. Decrease your speed for adverse weather or road conditions. Decrease your speed even further when a worker is close to the roadway.
Test Your Knowledge
- How far ahead does the manual say you should look?
- What are two main things to look for ahead?
- What’s your most important way to see the sides and rear of your vehicle?
- What does “communicating” mean in safe driving?
- Where should your reflectors be placed when stopped on a divided highway?
- What three things add up to total stopping distance?
- If you go twice as fast, will your stopping distance increase by two or four times?
- Empty trucks have the best braking. True or False?
- What is hydroplaning?
- What is “black ice”?
These questions may be on the test. If you can’t answer them all, re-read subsections 2.4, 2.5, and 2.6.