Stage 2 Course Content 7 — Effects of Natural Forces on Vehicles and Driving

• Forces on a vehicle to keep it moving and forces to stop it
• How to load cargo, etc. and a vehicle's stability
• Driving on curves and slopes
• Special characteristics of two-wheeled vehicles, riding posture, and riding
• Speed and impact
• Prevention of traffic pollution, global warming, etc.

A traveling vehicle generates kinetic energy with its own weight and speed. Therefore, natural forces such as inertia, centrifugal force, frictional force, etc. act on a vehicle while traveling. In order to drive safely, it is important to understand such natural forces and to know that there is a limit in controlling a vehicle.

1. Forces on a Vehicle to Keep It Moving and Forces to Stop It

1. Use of Frictional Resistance

A moving object tends to keep moving until an external force is applied on it. This is called the law of inertia. A traveling vehicle has an inertia to keep moving, even if the gear is shifted to neutral, due to inertia. To stop the vehicle, frictional resistance generated by brakes is used. In other words, the inertia is controlled using frictional resistance. However, note that there is a limit to frictional resistance. When a vehicle cannot be controlled within the limit of the force of friction resistance, you cannot stop a vehicle before an obstacle, even if you apply brakes after recognizing the object. In such a case, the vehicle may collide into the obstacle or skid off the road. The limit of frictional resistance is not always fixed and changes depending on the condition of the braking device and a coefficient of friction between the tires and the road surface.

Reference — "Coefficient of friction"

A numerical value indicating the "non-slipperiness" between two objects is known as a coefficient of friction. Objects can slip easily when the coefficient of friction is small. Objects are less slippery when coefficient of friction is large.

The range of the coefficient of skid friction on different kinds of road surfaces:

Kind of road surfaces	Dry	Wet
Concrete road	0.5～1.0	0.4～0.9
Asphalt road	0.5～1.0	0.3～0.9
Gravel road	0.4～0.6	—
Steel plate, etc.	0.4～0.8	0.2～0.5
Snowy road surface	—	0.2～0.5
Frozen road surface	—	0.1～0.2

(According to a report from the Public Works Research Institute)

A coefficient of skid friction is the coefficient of friction when the tires lock. Differences arise depending on the condition of the road surface and the tires (the degree of wear, internal pressure, tread pressure, etc.), as well as how the brake pedal is depressed.

2. A Vehicle's Stopping Distance

A vehicle cannot stop immediately after the brakes are applied. Bringing a vehicle to a stop requires a certain distance (stopping distance) which is the sum of the distance traveled from when a driver notices danger and apply the brakes until the brakes do start to engage (reaction distance), and the distance from when the brakes start to engage until the vehicle stops (braking distance). You should drive at a speed which enables you to stop the vehicle safely even if a dangerous situation occurs.

(Apply brakes → Brakes start to engage → The vehicle stops) (← Reaction distance →← Braking distance →) (←————— Stopping distance ————→)

1. Factors that make reaction distance longer

The reaction distance becomes longer when a driver is tired because it takes time for him/her to notice a danger and make a judgment.

2. Factors that make braking distance longer

When a road surface is wet, or the tires are worn, the coefficient of friction is significantly reduced, extending the braking distance. In such cases, the braking distance may become about twice as long as that on a dry road surface with good tire conditions. Also, the braking distance extends when carrying a heavy load. Therefore, overloading is dangerous as it further extends the braking distance.

Standard stopping distance (when applying brakes suddenly)

• Reaction distance → Proportional to the speed
• Braking distance → Proportional to the speed squared

① This table shows an example when a driver in normal condition applies brakes suddenly while driving on a dry paved road. The stopping distance may be longer depending on the conditions. For example, the distance on a rainy day becomes 1.5 times or more than shown in the table. On a snowy or frozen road surface, it becomes three times or more. Also, making a sudden stop while driving faster than 60 km/h is dangerous, because under such situation a vehicle often spins or skids instead of stopping successfully.

② The reaction distance in this table is calculated based on the assumption that the reaction time is 1 second, assuming that a driver is paying attention normally. In actual situations, it may be longer than this.

3. Effective Braking Method

When stopping at an intersection or a stopping position, first lightly step on the brake pedal well in advance to blink the brake lights 2 or 3 times, to give a signal to the vehicle behind that you are going to stop. Then, lightly step on the brake pedal again and gradually apply more pressure, and adjust the depressing depth of the brake pedal to stop the vehicle at the stopping position. This is an effective method to prevent a rear-end collision.

When you are forced to stop suddenly to avoid danger, depress the brake pedal strongly while holding the steering wheel straight, but avoid locking the tires (stopping their revolution). This is the method to stop the vehicle within the shortest braking distance while keeping the vehicle stable. If you apply the brakes too strongly in a stroke and the tires are locked, the braking distance increases, control of the steering wheel is lost, and the vehicle may skid. This often occurs on a slippery road. In such a situation, hold the steering wheel firmly without panicking, and keep applying the brakes. In any case, it is often difficult to take such actions in an emergency situation. The most important thing is to anticipate hazards appropriately and reduce speed in advance.

Reference — ABS (Antilock braking system)

When the tires are locked, the coefficient of friction decreases. The coefficient of friction becomes the greatest during the time between when the tires are turning freely and when they are locked. Using this maximum coefficient of friction effectively is a way to make the braking distance the shortest and make skidding unlikely to happen. Repetitive braking (the method of repeating the braking operation in which the driver applies the brakes and releases them just before the tires stop revolving) is a method for making maximum use of coefficient of friction. However, since it requires a high skill, if a general driver attempts repetitive braking, it will end up in longer braking distance.

ABS is a device that executes such repetitive braking controlled by a computer. A vehicle equipped with ABS is considered to be able to stop without being unstable in the shortest braking distance. However, since some experiments show that a vehicle equipped with ABS needs longer braking distance while traveling slowly or on a gravel road, you need to use ABS carefully.

Note that when ABS is activated, you will hear valve-operating sounds and feel small vibrations on the brake pedal. This is a characteristic effect (referred to as kickback) while ABS is operating, and you have to keep depressing while the brake pedal vibrates.

2. How to Load Cargo, etc. and a Vehicle's Stability

1. Change in Stability Depending on Loading Methods

The center of gravity is the place where the weight of a vehicle is concentrated at one central point, and there is balance. As the height of the center of gravity goes up, the vehicle becomes more unstable. Therefore, you should not pile up cargo too high. If the cargo is not loaded evenly on the left and right sides, the center of gravity is on one side, and you may lose control of the steering wheel, or the vehicle may overturn while traveling on a gentle curve. Also, if brakes are applied suddenly while traveling, the center of gravity shifts to the front, making the rear wheels likely to lock and the vehicle unstable.

(Do not pile up too high / Load evenly on the left and right sides)

2. Checking Cargo on a Hump or Dip Road

On a hump or dip road, such as a gravel road, the cargo may shift to one side or the rope may become loose. Therefore, the driver needs to periodically check the cargo.

3. Driving on Curves and Slopes

1. Driving on Curves and Corners

1. Driving that regulates the force to pull the vehicle outward

When a vehicle turns a curve or corner, the centrifugal force works due to inertia. The centrifugal force increases in proportion to the square of the speed (four times as great at double the speed and nine times as great at triple the speed). Also, the smaller the radius of a curve is, the greater the centrifugal force is. When this centrifugal force is greater than the frictional resistance between the tires and the road surface, it becomes very difficult to control the vehicle, and the vehicle may skid off the road or overturn. It is important to keep in mind that centrifugal force works while traveling on curves and to reduce speed sufficiently before entering a curve.

2. Predicting driving conditions ahead

On curves, etc., the vision ahead is often restricted and the condition ahead is difficult to judge. Therefore, it is important to anticipate that there may be an oncoming vehicle, etc. and to travel at an appropriate speed along the safest course in advance, based on the conditions such as how the road is winding, the degree of the curve, width of the road, view ahead, etc.

Reference — Points to note when driving through curves and corners

① When approaching a corner or curve, reduce speed sufficiently on the straight part of the road before the corner or curve. If you turn the steering wheel or apply the brakes while turning the steering wheel without reducing the speed, the vehicle tends to skid or overturn easily. ② Operate the steering wheel gently, instead of suddenly. ③ Do not go beyond the center of the road. Also, since an oncoming vehicle may cross over the center of the road, drive carefully. ④ Pay attention to inner wheelbase differential. Due to inner wheelbase differential, a vehicle may hit a pedestrian or bicycle when turning, or the rear wheel may roll over the shoulder. ⑤ While driving on a curve, it may be difficult to judge the condition of the road ahead. It is also important to take a safe course anticipating invisible hazards. ⑥ Do not overtake the vehicle ahead on curves and corners. Though overtaking is not prohibited on curves, the driver's vision ahead is restricted and speeding on a curve accompanies danger. Therefore, avoid overtaking.

2. Driving on Slopes and Mountain Roads

On upward slopes, since a resistance is applied on a vehicle according to the vehicle's weight and the degree of the grade, a vehicle needs a large amount of power to travel. On downward slopes, since a vehicle may accelerate due to the grade, the force to slow down the vehicle is required. Therefore, correct and well-timed gear-shifting and braking operations appropriate for the degree of grade are required. On mountain roads, the view ahead is poor as they have many slopes and curves. Furthermore, other bad conditions, such as narrow road width, poor road surfaces, the danger of falling rocks, roads with cliff on one side, etc. accumulate. Therefore, drive very carefully.

1. Starting on upward slopes

When starting on upward slopes, you need to prevent the vehicle from rolling backward using the hand brake (parking brake) in the case of a four-wheeled vehicle and the rear-wheel brake in the case of a two-wheeled vehicle.

2. Distance between vehicles when stopping on upward slopes

When stopping your vehicle behind another vehicle on an upward slope, do not come too close to that vehicle. If you stop too close, the vehicle ahead of you may roll backward when starting and collide with your vehicle.

3. Use of engine braking on downward slopes and distance between vehicles

① On long or steep downward slopes, use engine braking. At the same time, use the foot brake (in the case of a four-wheeled vehicle) or the front- and rear-wheel brakes (in the case of a two-wheeled vehicle) as necessary. When doing so, note that the engine may revolve excessively if the selected gear is too low. It is dangerous to use the foot brake or the front- and rear-wheel brakes too much, because doing so may cause a fade effect or vapor lock effect, which results in braking failure.

② On downward slopes, a vehicle accelerates and stopping distance is increased, so maintain a longer distance from the vehicle ahead on downward slopes than on flat land.

Reference — The effects of engine braking

Engine braking is more effective in lower gears (either the "L" or "1" position in the case of automatic transmission vehicles). It does not work while the clutch pedal is depressed (or the clutch lever is gripped in the case of a two-wheeled vehicle), or while the gearshift is in the neutral position. Engine braking is particularly effective in the following situations:

• When going down a long downward slope.
• When traveling on a slippery road, such as snowy or frozen roads.
• When reducing the vehicle speed after traveling at high speed.

※ The engine braking in automatic transmission vehicles is generally weaker and slower to come into effect, so make sure to activate them early.

Braking troubles

Fade effect: If the foot brake or the front- and rear-wheel brakes are used excessively on downward slopes, etc., the brake pads or discs overheat and the frictional force dramatically decreases, resulting in brake failure. This phenomenon often occurs with drum brakes.

Vapor lock effect: If the foot brake or the front- and rear-wheel brakes are used excessively, the brake pads, discs, etc. overheat, allowing the heat to pass through to the brake fluid and cause bubbles within the fluid. In this condition, since the pressure generated by applying the brakes does not transfer successfully, the brakes may not work well. This phenomenon also often occurs with drum brakes.

4. Yielding way on slopes

① It is difficult for a vehicle to start moving on an upward slope. Therefore, a vehicle going down should give way to the vehicle going up. ② When there is a turnout nearby, a vehicle going up should pull in and wait there. ③ On narrow roads with a cliff on one side where there is a risk of falling, regardless of which vehicle is going up or down, the vehicle on the cliff side should stop in a safe place beforehand and give way. ④ When carrying a heavy load and driving up a long upward slope at a slow speed, occasionally move to the left side of the road and proceed slowly, or stop to allow following vehicles to pass you in order to avoid traffic congestion.

5. Cautions against shoulders

On mountain roads, shoulders may be likely to crumble. Especially when it is raining or the snow is melting, do not get too close to the shoulders. If it is unavoidable to get close to a shoulder, get out of your vehicle and check the conditions of the shoulder beforehand.

Reference — Optical Illusions on long downward slopes

When entering a road with a different grade after traveling on a long downward slope, you may mistake a gentle downward slope for flat land, or flat land for an upward slope due to optical illusion. If you carelessly accelerate the vehicle based on such illusion, you may cause an unexpected accident.

Reference — Parking on a slope (Four-wheeled vehicle)

If it is unavoidable to park on a gentle slope, pay attention to the following:

• Apply the hand brake (parking brake) securely.
• Shift the gear into low on an upward slope, and into reverse on a downward slope. In automatic transmission vehicles, shift to "P".
• Use wheel chocks (if that's not possible, wedge large stones, etc. under the tires).

4. Special Characteristics of Two-Wheeled Vehicles, Riding Posture, and Riding

1. Special Characteristics of Two-Wheeled Vehicles

Two-wheeled vehicles have structural characteristics that the vehicle is kept stable by the rider's body while moving and that the vehicle becomes unstable when stopped.

1. The center of gravity and stability

Both the body of a two-wheeled vehicle and a rider have their own center of gravity. When a rider rides on a two-wheeled vehicle, a combined center of gravity of the rider and the vehicle is generated. When the line of action of the unified force that includes the gravitational force from the combined center of gravity of the rider and the vehicle and other forces (e.g., centrifugal force) meets the tire contact point on the ground, the two-wheeled vehicle is traveling in a stable state. This means that if the combined center of gravity of the rider and the vehicle shifts to one side, the rider will lose control of the handlebars or will overturn while turning a gentle curve.

2. Riding posture and operation

The combined center of gravity of the rider and the vehicle does not shift while the rider keeps the same riding posture. Shifting the combined center of gravity of the rider and the vehicle according to the change of the vehicle's state is the knack of stable riding. When going up on a slope, shift the combined center of gravity of the rider and the vehicle forward by taking a forward-leaning posture, in order to prevent the front wheel from floating up. On a downward slope, push your buttocks backward to maintain balance. When the road condition is bad, take a half-rising posture so that you can shift the combined center of gravity of the rider and the vehicle smoothly.

Reference — Shifting the center of gravity of a two-wheeled AT vehicle (motor scooter type)

On a motor-scooter-type two-wheeled AT vehicle (on which you cannot grip the tank with both knees), you should shift the center of gravity while taking the sitting posture. Keep your legs braced by pressing your entire soles against the step board, and maintain balance by shifting your posture.

Automatic two-wheeled vehicle characteristics and points to note

2. Correct Riding Posture

Taking a correct riding posture is essential to stabilize the center of gravity while traveling. Note the following points and take a correct and comfortable riding posture.

MT vehicle: ① Put the arches of the feet on the step and keep the soles almost level. ② Point the toes forward and grip the tank with both knees. ③ Hold the handgrips lightly with the wrists downward, imagining pushing the handlebars slightly forward. ④ Relax the shoulders and bend the elbows a little. ⑤ Straighten the back and look far forward.

AT vehicle (Motor scooter type): ① Sit in a position neither too far forward, nor too far backward. (On a vehicle type which has an adjustable backrest, adjust the backrest so that the movement of the arms and legs are not obstructed, and sit with the buttocks against the backrest.) ② Position the feet so that the soles are entirely on the step board and point the toes straight forward. The toes should not go outside of the step board. ③ Bend the knees naturally so that they will not open outward. ④ Hold the center of each handgrip with the angle of the wrists slightly downward. ⑤ Relax the arms, and slightly bend the elbows. ⑥ Relax the shoulders and back, and look ahead.

(Refer to p. 15 for choosing a vehicle type)

3. How to travel

1. Taking a road position

As two-wheeled vehicles seem further away or to be moving slower than their actual speed, they are often overlooked. Therefore, travel while avoiding entering the blind spots of surrounding vehicles. Also, since riders of two-wheeled vehicles travel avoiding humps and dips or stones on the road, they tend to look at the traveling lane immediately in front of the vehicle, and look to left forward of the road. Due to such tendencies, a rider's visibility is often more restricted than that of a driver of a four-wheeled vehicle. Consciously try to look far ahead. At the same time, since you can get less information on the condition behind you compared to while driving a four-wheeled vehicle, try to get more information on the condition behind you. To do so, the position of the two-wheeled vehicle is important. Try to travel in a position where you can ensure safety. (Refer to p. 138 for information on appropriate positions)

2. How to travel on curves

① When approaching a curve, reduce the speed sufficiently while traveling on the straight road before the curve. While proceeding through the curve, travel by constantly applying engine power to the wheels without disengaging the clutch. ② When turning, make a turn naturally by tilting the vehicle body (banking) instead of turning the handlebars. ③ Do not enter the right side of the road. Proceed carefully anticipating that an oncoming vehicle may cross over the center of the road. ④ Do not overtake the vehicle ahead on curves and corners. ⑤ In the middle of a curve, adjust your speed using the throttle. ⑥ In the latter half of the curve, ensure safety ahead and then slightly accelerate.

3. How to apply brakes

① Methods

There are three ways to apply brakes:

• Front-wheel brake operated by a brake lever
• Rear-wheel brake operated by a brake pedal or brake lever
• Engine braking operated by releasing the throttle or downshifting (shifting to a lower gear)

※ On some two-wheeled AT vehicles or motorized bicycles, both the front- and rear-wheel brakes are operated by the hand-brake levers.

② Cautions when applying brakes

• When applying brakes, maintain the vehicle body upright with the handlebars straight, and apply the front- and rear-wheel brakes at the same time while engine braking. While doing so, keep the correct riding posture to prevent falling forward.
• When braking on a dry road, apply the front-wheel brake slightly harder. On a slippery road, apply the rear-wheel brake slightly harder.
• The engine braking is more effective in lower gears. However, shifting to a low gear directly from a high gear may damage the engine or cause the rider to overturn. Therefore, downshift one gear at a time.
• When brakes are applied suddenly, the wheels stop rotating and cause skidding. Pump the brake pedal several times.

Reference — Effective braking method

As two-wheeled vehicles have shorter wheelbase and higher center of gravity compared to four-wheeled vehicles, when the brakes are applied, the traction on the rear wheel decreases, while the traction on the front wheel increases due to inertia. Therefore, as long as the brakes are applied gently, you can make the actual braking distance shorter by increasing the braking power for both the front and rear wheels. When applying the brakes strongly, slightly stronger brakes should be applied to the front wheel, while slightly weaker brakes should be applied to the rear wheel as the traction on the rear wheel decreases.

Sudden braking of vehicles equipped with ABS

Some two-wheeled vehicles may be equipped with ABS, and some ABS for AT vehicles can distribute braking power to the front and rear wheels when the front- or rear- wheel brake is applied. Even if the vehicle is equipped with ABS, avoid applying brakes suddenly when the vehicle body is tilted on a curve. Sudden braking should be applied only when the vehicle stands up straight. If the rear wheel is locked when the brakes are applied, the rear section of the vehicle body swings right and left. In such event, keep applying the brakes until the speed drops sufficiently, while keeping balance using the handlebars. Then, when the vehicle is proceeding straight ahead again, release the brakes. There is a danger of overturning if the brakes are released too early.

4. What to Know When Riding Double

Riding double on a large motorcycle or regular motorcycle has different operating characteristics from riding alone. Therefore, even if riding double is allowed, you should ride double only after you are skilled in riding the vehicle alone. Also, take a training on riding double.

1. Special riding characteristics of riding double

① As a two-wheeled vehicle becomes heavier with the weight of the passenger, the accelerating force decreases, while the centrifugal force and inertia increase. The center of gravity of the vehicle shifts backward and raised.

② Maintaining balance is necessary when riding on two-wheeled vehicles. This means that if a driver and a passenger do not move in harmony with each other, the vehicle may lose balance and overturn. The passenger often does not move as the driver expects or moves in a way opposite to the driver. For example, at the time of acceleration and deceleration, the movement of a passenger tends to be a beat behind. That can make the movement opposite that of the driver and may pull the driver backward when accelerating and push the driver forward when decelerating. Also, when turning a curve, the passenger may raise his/her body instinctively as the vehicle body is tilted and may lean suddenly in the middle of the curve. Such behaviors of passengers become prominent especially when the driver attempts to avoid danger. Consequently, the driver's ability to avoid danger decreases.

(A driver is pulled backward when the vehicle accelerates. / A driver is pushed forward when the vehicle decelerates.)

2. Operation based on riding double

• As the center of gravity shifts to the rear, the front wheel tends to lift off the ground slightly, causing a danger that the operation may become unstable. Therefore, the driver needs to operate the vehicle more prudently and show consideration to the passenger.
• Acceleration is not smooth as the total weight increases with the weight of the passenger. Exercise due caution when overtaking another vehicle, merging with a main through lane of an expressway, etc.
• If the driver starts or accelerates the vehicle suddenly, he/she may be pulled backward by the passenger or the passenger may fall down. Therefore, operate the accelerator or other devices gently without rushing.
• If the driver decelerates or applies the brakes to the vehicle suddenly, the traction on the front wheel becomes greater and steering becomes more difficult. Therefore, reduce speed gently without rushing.
• As the weight of the passenger falls on the back of the driver when decelerating, the driver should keep his/her upper arms close to his/her sides, and hold the handlebars firmly.
• When traveling through a curve, since the centrifugal force increases in proportion to the weight, the driver should tilt the vehicle inwards to keep balance with the centrifugal force. At such times, tell the passenger to take a posture similar to the driver before entering the curve.
• When the vehicle body is tilted, the passenger may raise his/her body instinctively because of the fear of the ground coming closer. Therefore, reduce speed sufficiently before entering the curve. If a passenger raises his/her upper body, there is a danger that balance will be lost, and the vehicle cannot make the turn.
• When riding double, the traction of the front wheel becomes weaker, and the operational stability deteriorates. Therefore, do not accelerate until you have passed through the curve.
• When changing course, ensure sufficient clearance to the front and rear as well as to the right and left, and change course without rushing, while slightly accelerating.
• Ride double on a two-wheeled vehicle with the understanding that avoiding danger becomes very difficult compared to riding alone.

3. Duty to give guidance to the passenger

The important point in riding double is that the driver and the passenger should ride in harmony with each other. Unlike in four-wheeled vehicles, a driver and a passenger cannot hear each other's voice well while traveling. Therefore, communicate with each other while waiting for the traffic signal to turn green, etc. Note that drivers have a chance to receive training on riding double whereas passengers don't. Drivers should give guidance to passengers before riding double.

• Do not move the feet off the steps.
• Ride as one with the driver. Putting both arms around the driver's waist is one way to do so.
• Sit with a proper distance from the driver.
• Look ahead carefully and understand the movement of the driver.
• Prevent the body weight from moving forward at the time of braking by firmly holding the grab bar, etc.
• Follow instructions of the driver.

4. Prohibition against riding double

Riding double is not allowed in the following cases:

① When riding a large or regular motorcycle without a rear seat, or riding a general motorized bicycle. ② When a person who has held a large motorcycle license for less than a year drives a large or regular motorcycle. However, if the person has held a regular motorcycle license for 1 year or more, he/she is allowed to ride double. ③ When a person who has held a regular motorcycle license for less than a year drives a regular motorcycle. ④ When a person who has a large motorcycle license and is less than 20 years of age or a person who has held a large motorcycle license for less than 3 years drives a large or regular motorcycle on an expressway. However, if the person is 20 years of age or older and has held a regular motorcycle license for 3 years or more, he/she is allowed to ride double. ⑤ When a person who has a regular motorcycle license and is less than 20 years of age or a person who has held a regular motorcycle license for less than 3 years drives a regular motorcycle on an expressway.

5. Speed and Impact

The severity of a traffic accident depends on the impact a vehicle gives to the other party or receives from the other party in a collision. The impact becomes greater in accordance with speed and weight. Also, the impact is large when a vehicle collides with a hard object instantly. For example, if a vehicle collides with a wall of concrete at a speed of 60 km/h, the impact is about the same as that received when falling from a height of approximately 14 m (about the 5th floor of a building). When a vehicle collides with an object, the vehicle or the object will be damaged or thrown into the air by the kinetic energy. This kinetic energy increases in proportion to the square of the vehicle speed. Therefore, as the speed increases, the collision causes greater damage. Drive especially carefully when driving at high speed.

Damage from a collision:

Equivalent fall height at 60 km/h collision:

Reference — Minimizing collision damage

To minimize damage from a collision, you should recognize danger as early as possible and slow down, in order to minimize the kinetic energy. For example, if you can reduce speed from 60 km/h to 30 km/h immediately before the collision, the kinetic energy generated by the collision can be reduced to one fourth of that caused when colliding at 60 km/h.

6. Prevention of Traffic Pollution, Global Warming, etc.

Vehicles are very useful for people who use them. On the other hand, quite a few people are suffering from traffic pollution such as exhaust gases, noise, vibration, etc. caused by such vehicles. When driving a vehicle, try to drive in a way to mitigate traffic pollution.

1. Exhaust Gases and Photochemical Smog

Exhaust gases emitted by vehicles contain substances harmful to the human body such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxide (NOx), and these exhaust gases are one cause of air pollution. Refrain from using vehicles while photochemical smog is there or when there is a risk of photochemical smog to appear due to air pollution.

2. Noises and Vibrations Caused by Traveling Vehicles

While traveling, vehicles cause traveling noises including exhaust noises, tire noises, etc., in addition to vibrations in the areas around roads. Considering that such noises and vibrations increase as a vehicle's speed or weight increases, drivers should keep the maximum speed and load limits, and avoid starting or accelerating suddenly, racing the engine, unnecessarily applying brakes suddenly or leaving the engine running.

3. Preventing Global Warming

Emission of nitrogen oxide, which is harmful to the human body, and carbon dioxide is a cause of global warming. To reduce emission of such substances, try to drive in a way that minimizes the environmental load (eco-driving), such as by starting gently, driving with less acceleration, not leaving the engine idling when the automobile is parked or stopped.

Reference — Relationship between speed and fuel consumption

There is a close relation between a vehicle's speed and fuel consumption, and fuel consumption increases when the speed is too fast or too slow. Sudden starting, sudden braking, racing the engine, idling for a long time while waiting for passengers or loading or unloading cargo not only cause extra fuel consumption but also increase the emission of carbon dioxide, which is one cause of global warming.

Eco-driving

Practicing eco-driving reduces exhaust gas and fuel consumption of automobiles, which leads to less damage to the environment, and leads to safer driving.

① Endeavor to start gently. ② Do not idle unnecessarily. ③ If stopping can be predicted, such as when a traffic signal is going to change, release your foot from the accelerator early. ④ Maintain sufficient distance from other vehicles and keep a steady speed. ⑤ Actively use engine braking. ⑥ Do not park poorly or illegally as it hinders the traveling of other vehicles. ⑦ Use the air conditioner sensibly. ⑧ Maintain correct tire pressure. ⑨ Avoid loading unnecessary cargo. ⑩ Check traffic information and your route beforehand and leave with more than enough time to reach your destination. ⑪ Be aware of the fuel consumption of your vehicle.

Let's Try — Course Content 7 — Check your understanding with right/wrong questions.

(See page 275 for answers.)

1. There is a close relation between an automobile's speed and fuel consumption, and fuel consumption increases when the speed is too fast or too slow.
2. To turn a curve safely, it is better to decelerate sufficiently on the straight road before the curve, rather than decelerating in the middle of the curve.
3. Two-wheeled vehicles naturally turn when tilted. Therefore, it is not necessary to reduce speed in any kind of curve.
4. When holding handgrips of a two-wheeled vehicle, hold them lightly with the wrists downward, imagining pushing the handlebars forward.
5. As the speed increases, the impact a vehicle gives to the other party or receives from the other party becomes greater in the event of a collision. Therefore, you need to be very careful of excessive speed.
6. On an asphalt road wet with rain or snowy road, the frictional resistance between the tires and the road surface decreases, and the braking distance is lengthened.
7. Braking distance and centrifugal force increase in proportion to the square of the speed. Therefore, if the speed doubles, the braking distance and the force that makes the vehicle to skid or overturn at curves become four times as much.
8. Stopping distance of a vehicle depends on how fast and strong you depress the brake pedal and does not depend on the condition of the road surface or tires.
9. Keeping the maximum speed and load limits contribute to smooth traffic but does not prevent traffic pollution.
10. You should try to drive in a way that minimizes the environmental load (eco-driving), such as by starting gently, driving with less acceleration, not leaving the engine idling when the vehicle is parked or stopped.

(正: right, 誤: wrong)