Road narrowingThailand

An introduction to the traffic rules and road signs of Thailand. Learn about driving, road safety and much more in our illustrated book, with answers to frequently asked questions.

For informational purposes only. Always follow official regulations. Some content and images were created with AI assistance.


1. Road narrowing

A road narrowing is a section where the available width of the road or carriageway becomes smaller. The narrowing may occur on both sides, on one side only, or because one or more traffic lanes end.

Drivers should reduce speed, observe approaching and adjacent traffic, maintain sufficient lateral clearance and merge when necessary. Warning signs do not always determine priority, so drivers must follow any priority signs, lane markings and local traffic rules.

What does a road-narrowing warning mean in Thailand?

Thai road-narrowing warnings describe a restricted carriageway ahead. Obey the traffic signs, signals and officer’s directions controlling the actual passage and adjust speed for the conditions.

🔗 network.doh.go.th • Thailand — 2020 highway-sign Regulation, actual signs/markings and separate controls

🔗 laksong.metro.police.go.th • Official Police-hosted Gazette — full enacted Road Traffic Act amendment 13, 2022

🔗 aipalync.org • Council of State Thai Act consolidation through amendment 12 — read with full amendment 13

Warning for a road narrowing. Warning for a road narrowing.

English • Traffic sign ต.22 • Road narrows on both sides. Reduce speed and watch oncoming vehicles.

ไทย • ต.22 • ทางแคบลงทั้งสองด้าน. ทางข้างหน้าแคบลงทั้งสองด้าน ให้ลดความเร็วและระวังรถที่สวนมา

Sources

🔗 Commons.wikimedia.org
🔗 Doh.go.th • กรมทางหลวง • คู่มือ พ.ศ. 2561 • เล่ม 1 • หน้า PDF 94

SVG source: Government of Thailand • Public domain • Original revision 2017-12-16. Wikimedia original unmodified.

Warning for a road narrowing on the left. Warning for a road narrowing on the left.

English • Traffic sign ต.23 • Road narrows on the left. Reduce speed and watch your lane position.

ไทย • ต.23 • ทางแคบด้านซ้าย. ทางข้างหน้าด้านซ้ายแคบลง ให้ลดความเร็วและระวังตำแหน่งรถในช่องเดินรถ

Sources

🔗 Commons.wikimedia.org
🔗 Doh.go.th • กรมทางหลวง • คู่มือ พ.ศ. 2561 • เล่ม 1 • หน้า PDF 95

SVG source: Government of Thailand • Public domain • Original revision 2017-12-16. Wikimedia original unmodified.

Warning for a road narrowing on the right. Warning for a road narrowing on the right.

English • Traffic sign ต.24 • Road narrows on the right. Reduce speed and watch your lane position.

ไทย • ต.24 • ทางแคบด้านขวา. ทางข้างหน้าด้านขวาแคบลง ให้ลดความเร็วและระวังตำแหน่งรถในช่องเดินรถ

Sources

🔗 Commons.wikimedia.org
🔗 Doh.go.th • กรมทางหลวง • คู่มือ พ.ศ. 2561 • เล่ม 1 • หน้า PDF 95

SVG source: Government of Thailand • Public domain • Original revision 2017-12-16. Wikimedia original unmodified.

Does a narrowing warning give you priority in Thailand?

No. A warning describes the reduced width, rather than allocating priority or setting a numerical speed limit. Follow any separate priority signs, signals and meeting rules, and slow enough to pass safely or wait before entering.

🔗 network.doh.go.th • Thailand — 2020 highway-sign Regulation, actual signs/markings and separate controls

🔗 laksong.metro.police.go.th • Official Police-hosted Gazette — full enacted Road Traffic Act amendment 13, 2022

🔗 aipalync.org • Council of State Thai Act consolidation through amendment 12 — read with full amendment 13

What should you do if traffic lanes merge at a narrowing in Thailand?

Read the lane-ending signs and markings, check surrounding traffic and signal any lane change as required. Apply the local merging rule and enter only when safe. Do not assume the driver in an ending lane always has priority, or confuse merging with meeting oncoming traffic.

🔗 network.doh.go.th • Thailand — 2020 highway-sign Regulation, actual signs/markings and separate controls

🔗 laksong.metro.police.go.th • Official Police-hosted Gazette — full enacted Road Traffic Act amendment 13, 2022

🔗 aipalync.org • Council of State Thai Act consolidation through amendment 12 — read with full amendment 13