道路反射鏡アメリカ合衆国

A traffic mirror is a convex roadside mirror that helps road users see around an obstruction or into a road with limited visibility.

They may be placed near intersections, narrow roads, bends, car-park exits, private driveways, tunnels or other locations where buildings, vegetation or road geometry obstruct the view.

A convex surface provides a wider field of view than a flat mirror, allowing more of the approaching road to be seen.

No. The reflected image is distorted, and objects normally appear smaller and farther away than they really are.

Not reliably. The curved image makes it difficult to estimate how fast another road user is approaching.

No. Distance can appear greater than it really is, so an approaching vehicle may reach the intersection sooner than expected.

Yes. Its position and viewing angle may leave parts of the road outside the reflected image. Small cyclists, motorcycles or pedestrians may also be difficult to notice.

No. It does not change priority. Drivers must continue to follow stop signs, give-way signs, traffic lights and the ordinary priority rules.

No. Another road user may be outside the reflected area, hidden by glare or too small to notice. Always check the road directly before proceeding.

Yes. The mirror does not replace the mandatory complete stop. Stop at the prescribed position, then use direct observation and the mirror as additional information.

Yes. You may proceed only when traffic with priority can continue without being forced to brake, stop or change direction.

Approach slowly, stop when required and scan the mirror for movement. Then look directly in both directions and continue only after confirming that the road is clear.

No. Alternate between the mirror and direct observation. The mirror should supplement rather than replace normal checks.

Yes. Rain, water droplets and spray may blur or partially obscure the reflected image.

Yes. Dew, condensation, frost, ice or snow may make the mirror difficult or impossible to use.

Yes. Sunlight may create glare or reflections that hide approaching road users.

Yes. Reflected headlights may make it difficult to determine the exact direction, distance or speed of an approaching vehicle.

Yes. Wind, impacts, vandalism, vibration or temperature changes may alter its orientation and make the reflected view inaccurate.

Do not rely on it. Proceed with additional caution and report the defect to the responsible road authority or property owner.

No. The applicable road or posted speed limit remains in force, but restricted visibility normally requires a lower approach speed.

No. Use the horn only where local law permits it and a warning is reasonably necessary to prevent danger.

Yes. It may help them observe approaching traffic, but they must also look directly and follow the applicable crossing and priority rules.

A mirror may generally be installed on private property with the owner’s permission, subject to local rules. Installing one on, above or beside a public road normally requires permission from the road authority.

No. Removing vegetation, relocating parking, improving the intersection layout or changing traffic circulation may provide a safer and more reliable solution.