Signal Timing in Japan: The 30-Meter and 3-Second Rules Explained
· GaimenGo Team
When exactly must you signal in Japan? The answer depends on what you're doing — and getting it wrong is one of the most common test failures.
Why Signal Timing Matters
In Japan, it's not enough to simply signal — you must signal at the correct time and perform the manoeuvre safely. Article 53 of the Road Traffic Act (道路交通法第53条 — Dōro Kōtsū Hō Dai 53-jō) and Enforcement Order Article 21 (施行令第21条 — Shikō-rei Dai 21-jō) govern when signals must be given.
The Two Key Rules
Rule 1: The 30-Meter Rule
Applies to:
- Left turns at intersections
- Right turns at intersections
- U-turns (転回 — Tenkai)
You must begin signalling when your vehicle is approximately 30 meters before the intended turning point and continue signalling until the action is complete.
Rule 2: The 3-Second Rule
Applies to:
- Lane changes (進路変更 — Shinro Henkō)
You must signal at least 3 seconds before changing lanes.
The Correct Safety Sequence
For exam and safe-driving purposes, remember this practical sequence:
- Check mirrors and surrounding traffic
- Turn on the indicator
- Perform a shoulder check (direct visual confirmation / blind-spot check)
- Execute the manoeuvre safely
Safety confirmation is not a one-time action — continue observing during the manoeuvre.
Roundabout Exception
The standard 30-meter rule does not apply inside roundabouts (環状交差点 — Kanjō Kōsaten). Signal left sufficiently before exiting so your intention is clear to surrounding traffic.
Quick Reference Table
| Situation | Signal Timing | Direction |
|---|---|---|
| Left/Right turn at intersection | ~30m before turning | Left or Right |
| U-turn (転回 — Tenkai) | ~30m before turning | Right |
| Lane change (進路変更) | ≥3 seconds before | Left or Right |
| Pulling away from roadside | After safety confirmation | Right |
| Pulling over to stop/park | After safety confirmation | Left |
| Roundabout exit | Sufficiently before exit | Left |
Key Exam Questions
- 'When changing lanes, you must signal 30 meters before the change' → False
- 'When making a U-turn, you must signal 3 seconds before' → False
- 'You must keep the signal on until the manoeuvre is complete' → True
- 'You should perform a shoulder check before changing lanes' → True
Reference: 道路交通法第53条, 施行令第21条.