Safe Speed and Distance between Vehicles

1. Maximum Speed Limit

1.1 Observing the Maximum Speed Limit

When driving a vehicle, a driver must make efforts to drive safely, observing regulated speed limits specified according to the conditions of the road and traffic and legally designated speed limits prescribed according to vehicle type.

1.2 Regulated Speed Limit

1. On roads where the maximum speed limit is designated by traffic signs or pavement markings, vehicles and streetcars must not drive exceeding that speed (the regulated speed limit).
2. On roads where the maximum speed limit designated by traffic signs or pavement markings is over 30 km/h, general motorized bicycles must not drive exceeding 30 km/h (the legally designated speed limit).

Sample maximum speed limit traffic signs and pavement markings:

③ On roads where auxiliary signs designate the maximum speed limit for specific types of vehicles only, such types of vehicles must not drive exceeding that maximum speed.

1.3 Legally Designated Speed Limit

On roads where the maximum speed limit is not designated by traffic signs or pavement markings (excluding national expressways), vehicles must not drive exceeding the maximum speed limit (legally designated speed limit) prescribed by laws and regulations for that type of vehicle.

Legally designated speed limits when towing another vehicle:

2. Speed and Stopping Distance

2.1 Reaction Distance, Braking Distance, and Stopping Distance

1. Vehicles cannot stop suddenly. 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 steps on 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).
2. Since the stopping distance becomes longer with higher speed, drivers must be constantly aware of stopping distance and drive vehicles at a speed that will allow for safe stopping in the event of danger.

Stopping distance for regular passenger automobiles:

2.2 When Stopping Distance Becomes Longer

1. The reaction distance becomes longer when a driver is tired because reaction is slower compared to when the driver is not tired, and it takes longer to make a judgment after noticing danger.
2. The braking distance becomes longer when a vehicle is traveling on a road wet due to rain, carrying a heavy load, etc. because of frictional force, etc.
3. When the road surface is wet and the tires are worn, the stopping distance may become about twice as long as that on a dry road surface with tires in good condition. On downward slopes, the stopping distance becomes longer depending on how steep it is.

3. Safe Speed and Distance between Vehicles

3.1 Speed in Response to Road Environment, etc.

A driver must travel at a safe speed taking into account road and traffic conditions, weather, visibility, etc. when driving a vehicle, even within the determined speed.

3.2 Maintaining a Safe Distance between Vehicles

A driver must take into account the weather, the road surface, tire conditions, the weight of the load, etc. and follow at a safe distance from the vehicle ahead to avoid rear-end collision even if it stops suddenly. Use the stopping distance as a guide to determine the safe distance.

Guide for safe distance between vehicles (on a dry, paved road):

Keeping a safe distance between vehicles in response to conditions:

1. When the road surface is slippery, stopping distance becomes longer. Follow at a distance 1.5 times as long for a dry road on road surfaces with normal rain, and at a distance three times as long or more on icy road surfaces.
2. When following a large vehicle, following at a short distance reduces visibility ahead, blocking the view of signals, oncoming vehicles and other conditions. Follow at a distance that ensures sufficient visibility.
3. Inside a tunnel, it is difficult to judge distance, and the distance between vehicles tends to become shorter because the eyesight is drawn to the taillight of the vehicle ahead. Look at the entire tunnel as much as possible, not just at the vehicle ahead, and consciously follow at a longer distance.

4. How to Apply Brakes

4.1 How to Apply Brakes in a Four-Wheeled Vehicle

1. Step as lightly as possible to begin, and gradually apply more pressure as needed.
2. Pump the brake pedal several times (cadence braking). This method is especially effective when the road condition is slippery. By applying the brakes over several steps of the pedal, the brake light flashes, becoming a signal to the vehicle behind and preventing a rear-end collision.

4.2 How to Apply Brakes on a Two-Wheeled Vehicle

Methods:

There are three ways to apply brakes on two-wheeled vehicles:

1. Front-wheel brake operated by a brake lever.
2. Rear-wheel brake operated by a brake pedal or a brake lever.
3. Engine braking operated by releasing the throttle (accelerator) or downshifting (shifting to a lower gear).

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

Points to note:

1. Maintain the vehicle body upright with the handlebars straight, and apply the front- and rear-wheel brakes at the same time while engine braking. Maintain the correct riding posture so to prevent tipping forward.
2. When braking on a dry road, apply the front-wheel brake slightly harder. On a slippery road, apply the rear-wheel brake slightly harder.
3. The engine braking is more effective in lower gears. 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.
4. When brakes are applied suddenly, the wheels stop rotating and cause skidding. Therefore, pump the brake pedal several times.

4.3 Prohibition against Sudden Braking

1. A rider must not apply the brakes suddenly except when necessary to avoid danger. When sudden braking is unavoidable on an automobile equipped with an antilock braking system (ABS), stepping firmly and fully on the brake in one movement and keeping it depressed are required to activate the system.
2. When driving, do not use the brakes thoughtlessly. Reduce speed gradually using accelerator operation (engine braking) as much as possible when stopping.
3. Sudden braking is dangerous when traveling at high speeds or on slippery roads, because it can cause skidding.

5. Proceeding Slowly

5.1 Definition of Proceeding Slowly

5.2 Where to Proceed Slowly

Vehicles must proceed slowly in the following places:

1. Where a "Proceed slowly" sign is present
2. At an intersection where visibility to the right and left are poor (Excluding where traffic is controlled by traffic lights, etc. or when proceeding along a road with the right of way)
3. Near the corner of a road
4. Near the top of an upward slope
5. On a steep downward slope

Additional situations requiring proceeding slowly:

In addition to places, vehicles must proceed slowly in the following cases:

1. When proceeding on paths for pedestrian use, with permission.
2. When passing beside a pedestrian, etc. and a safe distance cannot be secured.
3. When turning right or left to exit a road.
4. When passing beside a safety zone where pedestrians are present.
5. When passing beside a streetcar stopped at a streetcar stop with a safety zone.
6. When passing beside a streetcar stopped at a streetcar stop without a safety zone when no passengers are getting on or off and when a distance of 1.5 m or more from the streetcar can be secured.
7. When turning left or right at an intersection.
8. When entering a road with the right of way or a wide road.
9. When proceeding in an area with mud or puddles.
10. When protecting the passage of people with physical disabilities, senior citizens with difficulty proceeding, school children, or preschool children.
11. When passing beside a school or kindergarten bus which is stopped to let school children or preschool children get on or off.