warning sign
Loose road surface ahead
Thai road sign ต.39 — Loose road surface ahead. Meaning: The road surface ahead has loose material such as gravel or stones. 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: ป้ายเตือนผิวทางร่วน
Independent English reference · Source: Department of Highways · Sign ต.39
Road response
On the road
Driver action
What should you do?
Reduce speed before the loose surface and avoid abrupt steering, braking, or acceleration.
Exam-style scenario
Read the situation
Gravel covers the next section and a cyclist is following behind your vehicle.
Best response: Slow before the gravel and avoid abrupt inputs that could reduce control or throw loose material toward the cyclist.
Sign comparison
Don’t confuse it
This sign
Loose road surface ahead
Compare with
Slippery road
Key difference
Flying stones identify loose material on the surface; the skidding-car symbol warns of low grip without depicting gravel.
Put sign knowledge into practice.
Answer exam-style questions about road signs, traffic lights, and lane markings in clear English.
