Carriageway shifts left ahead
The driving lane shifts to the left ahead, often where the road realigns around an obstacle, bridge, or construction zone. Reduce speed, follow lane markings carefully, and keep your vehicle within the shifted lane path.
Verified as Thai road sign ต.42 from Thai Department of Land Transport sign series on 2026-05-15.
Study guide
Connect this sign to practice
Carriageway shifts left ahead is a hazard cue, not a rule. On the Thai exam that distinction matters. Run a few questions to see how the scenario gets framed: which way to slow, who has priority, and what the next sign is likely to be.
Now see it in questions.
Spotting Carriageway shifts left ahead in isolation is one thing. Recognising it inside a real exam-style question, among lookalikes and trick wording, is another. The diagnostic mixes it in for you.
