4.3 Turning, U-Turns & Reversing Rules

4.3 Turning, U-Turns & Reversing Rules

Quick Summary: Vehicle maneuvers—including turning, U-turns, and reversing—require rigorous adherence to signaling distances, channelized lane positioning, and statutory spatial restrictions under Thailand's Land Traffic Act B.E. 2522. Under section 36, you must signal at least 30 metres before turning, changing lanes, or stopping. Section 53 bans U-turns in safety zones, in congested places, on bridges, within 100 metres of the foot of a bridge, and at junctions unless a sign allows it. Never reverse on an expressway or motorway, in a tunnel, or across a junction.

Executing turns, directional reversals, and backing maneuvers introduces substantial conflict risks into traffic streams. The Department of Land Transport (DLT) places immense emphasis on testing candidates on precise advance signaling distances, designated turn paths, statutory U-turn restrictions, and the severe prohibitions governing vehicle reversing. Understanding these legal provisions ensures safety and legal compliance across Thailand's road network.

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1. Statutory Advance Signaling Requirements (Sections 36 to 38)

Under section 36 of the Land Traffic Act, a driver about to turn, let another vehicle pass, change lanes, slow down, stop, or park must signal:

• 30-Metre Rule: Signal at least 30 metres before turning, changing lanes, stopping, or parking.
• 60-Metre Visibility: The signal must be visible to other drivers from at least 60 metres away.
• Light Signals (section 38): Red stop lights at the rear when stopping. Amber indicators (or flashing white/amber lights) when turning, changing lanes, or overtaking.
• Hand Signals (section 37): Use these when lights cannot be seen or do not work. Thai hand signals are all made with the right arm out of the window:
  • Slowing down: Right arm straight out at shoulder height, hand waved up and down several times.
  • Stopping: Right arm out at shoulder height, forearm raised upright, palm facing forward.
  • Letting another vehicle pass or overtake: Right arm out at shoulder height, hand waved forward several times.
  • Turning right or moving right: Right arm held straight out at shoulder height.
  • Turning left or moving left: Right arm out at shoulder height, wrist bent up and hand waved toward the left several times.

A common trap is to mix up the stop signal (forearm raised, palm forward) with a turn signal.

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2. Proper Turning Procedures & Lane Selection

Correct lane positioning before, during, and after a turn prevents side-swipe collisions and maintains traffic throughput.

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Left Turns (การเลี้ยวซ้าย)

1. Approach Positioning: Move into the extreme left-hand travel lane at least 30 meters prior to the intersection while displaying the left turn signal.
2. Vulnerable User Check: Check interior rearview and left exterior mirrors, followed by a mandatory head-check over the left shoulder to verify that no motorcycle or bicycle is filtering along the left curb.
3. Maneuver Execution: Decelerate smoothly without braking abruptly. Turn tightly into the nearest left lane of the receiving roadway. Swinging wide into outer travel lanes is a dangerous traffic infraction.

The 'Turn Left on Red' Rule (เลี้ยวซ้ายผ่านตลอด)

A frequent point of confusion on the DLT exam involves turning left at a red traffic light:

• General Statutory Rule: Under Thai law, a red traffic light signifies an absolute command to STOP. Turning left on red is strictly illegal by default.
• The Permitted Exception: Motorists may turn left against a steady red light ONLY IF there is an explicit regulatory sign installed stating 'Turn Left on Red with Care' (ป้ายเลี้ยวซ้ายผ่านตลอด) or a separate green left-turn arrow illuminated.
• Mandatory Safety Protocol at Permitted Signs: Even where a 'Turn Left on Red' sign is posted, drivers do not have automatic right-of-way. The driver must:
  1. Bring the vehicle to a complete halt or slow to a walking crawl before the stop line.
  2. Yield absolute priority to crossing pedestrians on zebra crossings.
  3. Yield to all vehicles traveling through the intersection on a green light from the right.
  4. Merge into the leftmost lane only when a completely unobstructed gap is available.

Right Turns (การเลี้ยวขวา)

1. Approach Positioning: Signal right at least 30 meters prior and guide the vehicle into the rightmost lane adjacent to the yellow centerline or central median barrier.
2. Centerline Protocol: Advance into the intersection up to the center turning point. Keep the steering wheels oriented strictly straight forward while waiting for a traffic gap; turning the wheels prematurely means a rear-end impact will push the car directly into oncoming traffic.
3. Yielding Mandate: Yield absolute right-of-way to oncoming through-traffic and oncoming vehicles turning left into the same receiving roadway.
4. Receiving Lane: Execute the right turn smoothly into the authorized rightward lane without cutting across the opposing lane's corner markings.

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3. Statutory U-Turn Regulations & Prohibitions (Sections 52 and 53)

Making a U-turn (การกลับรถ) means crossing the path of traffic in both directions. The Land Traffic Act restricts where and when you may do it:

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Where U-Turns Are Banned (Section 53)

1. Where a sign prohibits turning or U-turns (ป้ายห้ามกลับรถ).
2. In a safety zone (เขตปลอดภัย), such as a painted or raised refuge for pedestrians.
3. In a congested place (ที่คับขัน), meaning somewhere with heavy traffic or obstructions, or where danger can be foreseen.
4. On a bridge (บนสะพาน).
5. Within 100 metres of the level ground at the foot of a bridge (ในระยะหนึ่งร้อยเมตรจากทางราบของเชิงสะพาน).
6. At a junction (ทางร่วมทางแยก), unless a traffic sign allows U-turns there.

When U-Turns and Right Turns Must Wait (Section 52)

On a two-way road, you must not make a U-turn or a right turn while another vehicle is approaching or following within 100 metres, unless it is safe and does not obstruct that vehicle.

Solid centre lines (section 47) and the rules on safe turning still apply, so a U-turn across a double solid line is also wrong.

Authorized U-Turn Facilities

On major Thai national highways and urban expressways, U-turns must be performed exclusively at engineered facilities, such as:

• Dedicated Median Openings (จุดกลับรถ): Equipped with deceleration pockets and regulatory U-turn signage.
• Horseshoe Flyovers (สะพานกลับรถเกือกม้า): Elevated loop bridges carrying reversing traffic safely over active throughway lanes.
• Under-Bridge Turnarounds (จุดกลับรถใต้สะพาน): Depressed loops passing beneath waterway bridges or elevated viaducts.

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4. Reversing Regulations & Safety Procedures (การถอยรถ)

Reversing is an inherently hazardous maneuver due to large rear blind spots and restricted steering response.

• Never Reverse In These Places: Reversing is extremely dangerous, and in these places it also breaks motorway rules or the Act's general duty to drive safely:
  • On expressways, motorways, and tollways (ทางพิเศษ / มอเตอร์เวย์).
  • Inside road tunnels, underpasses, or enclosed viaduct galleries.
  • Directly within active road intersections, roundabouts, or pedestrian crosswalks.
  • On elevated flyovers, bridges, or steep blind inclines.
• Operational Reversing Guidelines:
  • Reversing must be conducted at a slow, controlled crawl (idle speed).
  • The driver must inspect all three mirrors and perform a direct physical head-check over the left and right shoulders through the rear windscreen.
  • Hazard warning flashers should be activated if backing into a confined driveway or parking stall adjacent to an active roadway.
  • If reversing across a sidewalk or footpath into traffic, the driver must stop completely and yield to all pedestrians and approaching vehicles before crossing the property line.

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5. Summary Reference: Maneuver Rules & Prohibitions