Curve Mirror

Curve mirrors are facilities installed for traffic safety, aimed at allowing drivers to check for other vehicles that may be hidden from view at intersections, road bends, and sharp curves. They are installed by the city and Tokyo Metropolitan Government.
The city installs curve mirrors in areas where visibility is poor for drivers on city roads to enhance traffic safety.
Additionally, in the city, there are curve mirrors installed and managed by individuals to ensure visibility from private properties, such as the entrances and exits of personal parking lots, in addition to those installed by the city.
While curve mirrors are very useful for recognizing the presence of approaching vehicles in advance, they also carry certain risks as outlined below.

Danger of Curved Mirrors

Danger 1: "Blind Spot"

There are "blind spots" that are not reflected in the mirror of a curve mirror.
Especially in places where many children pass, caution is necessary.
Children are shorter, so they can enter the "blind spots" of the curve mirror.
Drivers should assume that even if they check the curve mirror and confirm that there are no approaching vehicles, children or others may be hidden in the "blind spots," and they should proceed at a speed that allows them to stop immediately while slowing down, and it is necessary to visually confirm safety directly with their own eyes.

Danger 2: "Unstoppable Car"

In general, drivers should stop or slow down at intersections with poor visibility where no curve mirrors are installed, and proceed while visually confirming safety. However, when curve mirrors are installed, drivers can confirm that no approaching vehicles are present from a distance, which may lead them to enter the intersection without reducing speed.
In such cases, if a vehicle is traveling at high speed and a collision occurs with pedestrians or others in the "blind spot," the severity of injuries can be serious.
This means that the curve mirrors, which are originally installed for safety, end up increasing traffic hazards, resulting in a contradiction.
Curve mirrors are merely supplementary facilities for traffic safety, and the information obtained from them should be considered as "reference" only. Ultimately, it is necessary for drivers to stop or slow down and visually confirm safety directly with their own eyes.

Summary of Risks

Recently, it has gradually been recognized that curve mirrors for traffic safety can sometimes induce traffic accidents.
Curve mirrors are merely supplementary facilities for traffic safety.
To prevent tragic accidents, it is essential to visually confirm safety directly with your own eyes.
Just because there is a curve mirror, do not neglect to slow down or stop; let's be mindful of safe driving.

When the city installs a curve mirror

The city takes the dangers of curve mirrors seriously and makes careful decisions when installing them.
There are the following conditions for the installation of curve mirrors.

Target Road

The applicable roads must meet both of the following criteria 1 and 2.

1. A road with a width that does not obstruct vehicle passage even after installing a curve mirror.
2. If any of the following apply
   1. City Road (including cases of entering and exiting Public Facilities)
   2. Roads (when intersecting with city roads)
   3. Private road that allows passage for an unspecified number of vehicles (when intersecting with a city road)

Consideration of Road Shape

Among the "targeted roads" mentioned above, we will consider the installation of curve mirrors if the sight distance cannot be secured due to the following road shapes.

1. Curved sections and bent sections (parts of curves and L-shaped bends)
2. In the absence of chamfering.
3. If there is no sidewalk on the road on the intersection side.

If not installed due to environmental factors

Even if the above conditions are met, installations will not be made in places like the following.

1. Roads with "Stop" traffic regulations
   Curve mirrors at intersections with "Stop" traffic regulations may induce failure to stop, raising concerns about the occurrence of more serious accidents, so they will not be installed.
2. Roads near elementary school routes and Children's Centers
   In places where many small children pass by, shorter children may enter a "blind spot," which is dangerous, so in principle, they are not installed.
3. It will not be installed if it hinders the use of adjacent land or buildings.

[FAQ1] Even if I stop at the stop line for 'Stop', I can't see if any cars are coming. Could you please install a curve mirror?

Answer

If there is a "Stop" traffic regulation, drivers must stop their vehicles just before the stop line.
Since the stop line is set before the intersection, it is usually not possible to see vehicles on the crossroad from the stop location, and a curved mirror is not installed.
Even after stopping, drivers must proceed slowly and confirm safety visually, and if there is a risk of obstructing the progress of vehicles on the crossroad, they must take measures such as stopping again.

Furthermore, as mentioned in the above section on the "Dangers of Curve Mirrors," if a curve mirror is installed at an intersection with a "Stop" traffic regulation, it may encourage drivers to proceed without stopping or slowing down. This raises concerns about the potential for more serious accidents compared to situations without a curve mirror. Therefore, curve mirrors will not be installed in areas where a stop regulation is in place.

[FAQ2] Are there dangerous intersections where accidents actually occur? Can a curve mirror be installed?

Answer

A curve mirror will not be installed solely for the reason that an accident has occurred.
Installing a curve mirror may encourage driving without stopping or slowing down, which could lead to more serious accidents compared to situations where no curve mirror is present. Therefore, we will carefully consider this in consultation with the Tama Central Police Station.