warning sign
Roadway narrows ahead on the left side
Thai road sign ต.23 — Roadway narrows ahead on the left side. Meaning: The roadway narrows from the left side ahead. Learner-manual coverage: this identity is shown in the current DLT car-driver learner manual. Inclusion does not mean it appears in every theory test.
Thai name: ป้ายเตือนทางแคบ
Independent English reference · Source: Department of Highways · Sign ต.23
Road response
On the road
Driver action
What should you do?
Reduce speed and keep clear of traffic affected by the narrowing lane edge.
Exam-style scenario
Read the situation
The left edge moves inward ahead while a vehicle is travelling beside you on the right.
Best response: Hold a safe position away from the closing left edge without moving into the vehicle on your right.
Sign comparison
Don’t confuse it
This sign
Roadway narrows ahead on the left side
Compare with
Roadway narrows ahead on both sides
Key difference
Only the left edge moves inward; the both-sides sign shows two converging edges and a more general reduction in width.
Put sign knowledge into practice.
Answer exam-style questions about road signs, traffic lights, and lane markings in clear English.
