3.2 Transverse Markings, Junction Boxes & Crossings
Key Takeaways
A solid white stop line means stopping completely behind the line for a red light, a stop sign, or an officer's signal.
A broken give-way line means slowing down and giving way to traffic on the major road, stopping only if traffic is coming.
Drivers must slow for crossings (section 70) and stop for pedestrians on them; overtaking within 30 m before a crossing (section 46) and parking within 3 m of it (section 57) are banned.
Never enter a yellow grid box unless your exit is clear; section 71(3) requires waiting behind the stop line even on green when the junction is blocked.
3.2 Transverse Markings, Junction Boxes & Crossings
Quick Summary: Transverse road markings run across traffic lanes to govern immediate right-of-way transitions, vehicle halts, and pedestrian interactions. Drivers facing a solid white stop line must bring their vehicle to a complete, motionless halt entirely behind the line. Drivers must slow down approaching a crossing (section 70 of the Land Traffic Act) and stop for pedestrians using it. Overtaking within 30 metres before a crossing is banned (section 46). At intersections featuring a yellow diagonal grid box, drivers must never enter the box unless their exit lane is completely clear, regardless of green traffic signals. Directional lane arrows are mandatory; drivers must follow the path indicated by their lane's arrows once entered.
While longitudinal markings guide vehicles along the length of a roadway, transverse road markings run across the width of traffic lanes perpendicular or diagonally to the travel flow. Under the Thailand Land Traffic Act B.E. 2522 (1979) and Department of Land Transport regulations, transverse markings establish precise spatial thresholds for stopping, yielding, pedestrian safety, and junction clearance. Violations of transverse markings are among the most heavily penalized infractions in Thai traffic law because they directly govern high-conflict intersection points where severe right-angle and pedestrian collisions occur.
1. Transverse Stop Lines (เส้นหยุด)
A transverse stop line is a wide, continuous solid white line painted straight across a traffic lane or approach road, positioned perpendicular to the direction of travel.
Legal Mandate Under Thai Law
Under Section 22 and Section 24 of the Land Traffic Act B.E. 2522, whenever a driver faces a red traffic signal, a physical octagonal Stop sign, a railway level crossing warning signal, or an explicit manual stop signal from a uniformed traffic police officer, the driver must bring their vehicle to a complete, motionless halt entirely behind the transverse stop line.
Critical Stopping Regulations
- Zero Encroachment: No part of the vehicle—including the front bumper, front tyres, or overhang—may cross, straddle, or extend beyond the outer edge of the stop line.
- Pedestrian Walkway Clearance: The space immediately downstream of the stop line is generally designated as a pedestrian crosswalk or safety buffer zone. Stopping past the stop line forces pedestrians into live traffic lanes, creating severe hazards.
- Advanced Stop Lines (Motorcycle / Bicycle Waiting Boxes): At many major signalized intersections across Bangkok and urban provinces, the road surface between the primary stop line and the pedestrian crosswalk contains a secondary zone marked with motorcycle or bicycle symbols (Advanced Stop Line or bike box). Cars must stop behind the first (outer) stop line and leave the forward box for two-wheelers.
2. Give-Way / Yield Lines (เส้นให้ทาง)
A give-way line consists of a transverse broken white line (a series of dashed white blocks) painted across a lane, frequently paired with an inverted white triangular yield symbol painted directly onto the asphalt surface upstream of the line.
Operational Rules
- Yielding the Right-of-Way: A give-way line indicates that the driver is traveling on a subordinate (minor) road approaching an intersection with a major priority roadway, a roundabout entry, or an expressway merge lane.
- Deceleration vs Complete Stop: Unlike a solid stop line, a give-way line does not legally require an absolute complete stop if the intersecting road is completely clear. The driver must decelerate to a cautious speed, actively scan both directions, and grant unconditional right-of-way to all crossing vehicles, bicycles, and pedestrians.
- Mandatory Stop Condition: If any vehicle or pedestrian is approaching on the priority roadway within a distance that could cause a hazard, the driver must come to a full stop before the dashed give-way line and wait until a safe gap emerges.
3. Pedestrian Zebra Crossings (ทางข้าม / ทางม้าลาย)
A pedestrian zebra crossing consists of broad, longitudinal white rectangular stripes painted across the full width of the roadway at regular intervals, resembling zebra striping.
Pedestrian Priority at Crossings
Section 70 of the Land Traffic Act requires every driver approaching a crossing to reduce speed. The crossing marking itself means drivers must stop and let pedestrians cross first. Section 32 also requires special care around children, older people, and people with disabilities. Since the 2022 amendment, failing to stop for a pedestrian at a crossing carries a fine of up to 4,000 THB and 1 demerit point. If anyone is on the crossing, stepping onto it, or clearly waiting to use it, stop before the crossing and let them cross.
Strict Statutory Prohibitions at Zebra Crossings
To protect vulnerable road users, Thai traffic law establishes three uncompromising statutory prohibitions around pedestrian crossings:
- Overtaking Prohibition (Section 46): Drivers are strictly forbidden from overtaking or passing another vehicle within 30 meters of an approach to a pedestrian crossing or while traversing the crossing itself. If a vehicle in an adjacent lane slows down or stops near a zebra crossing, following and adjacent drivers must assume a pedestrian is crossing and stop immediately. Overtaking a car that has stopped at a crossing is one of the most dangerous mistakes a driver can make, and it is an offence.
- Parking Ban: Under section 57, you must not park on a crossing or within 3 metres of it. A parked car there hides pedestrians from approaching drivers.
- No Horn Bullying: Section 14 allows the horn only when necessary or to prevent an accident. Honking at or edging toward pedestrians to hurry them breaks that rule.
4. Yellow Diagonal Grid Junction Boxes ("Yellow Box" / เส้นทแยงเหลืองในทางแยก)
The yellow diagonal grid junction box—widely known as the "Yellow Box" or criss-cross yellow lines (เส้นทแยงเหลืองในทางแยก)—consists of bright yellow painted lines forming a large crosshatched diagonal grid over the center of an intersection or roadway junction.
The Anti-Gridlock Principle
Yellow grid boxes are engineered to eliminate intersection gridlock (where vehicles stuck inside an intersection block perpendicular traffic flows from moving during their green light phase).
The Fundamental Legal Rule
Drivers are strictly prohibited from driving into a yellow diagonal grid box unless their exit lane beyond the junction is completely clear, unobstructed, and capable of accommodating their entire vehicle.
The Green Traffic Light Fallacy
A frequent question on the DLT theory examination tests the scenario where a driver faces a green traffic light at an intersection with a yellow grid box, but traffic on the far side of the intersection is backed up:
- Correct Driver Action: The driver must halt before the intersection stop line and wait, despite the green light.
- Illegal Action: Entering the yellow box and getting stuck inside when the signal transitions to amber and red blocks cross-traffic, paralyzing the intersection. Stopping in the box breaks the marking's meaning and the junction rule in section 71(3), and can be ticketed.
The Rule Behind It (Section 71(3))
Section 71(3) of the Land Traffic Act says the same thing for every junction: even on green, if vehicles inside the junction block your way through, you must wait behind the stop line until you can clear it. The yellow box just marks the area where you must never stop.
5. Directional Arrows Painted on Road Pavements (ลูกศรบอกทิศทางบนผิวทาง)
Directional lane arrows are painted white arrows applied directly onto the center of traffic lanes approaching intersections, multi-lane splits, and expressway interchanges.
Types of Pavement Arrows
- Straight-Only Arrow (ลูกศรตรงไป): Mandatory straight-through travel. Vehicles in this lane are legally barred from turning left or right.
- Turn-Only Arrow (ลูกศรเลี้ยวซ้าย / เลี้ยวขวา): Mandatory turn. Vehicles entering this lane must execute the turn in the indicated direction; driving straight ahead is strictly prohibited.
- Combined Arrow (ลูกศรตรงไปและเลี้ยว): Permitted choice. The driver may either continue straight or execute the indicated turn from this designated multi-purpose lane.
- Lane Reduction / Merge Arrow (ลูกศรเปลี่ยนช่องเดินรถ): Diagonal curved arrows indicating that the lane is terminating ahead and traffic must safely merge into the adjacent continuous lane.
Legal Obligation and Intersection Discipline
- Mandatory Maneuver Execution: Once a vehicle enters an approach lane marked with directional arrows and bounded by a solid white line, the driver must complete the maneuver indicated by the arrows.
- Prohibited Last-Second Maneuvers: Section 22 requires drivers going straight to be in a straight-ahead lane, and drivers turning to be in a turn lane, from where the markings begin. If you find yourself in the wrong lane, follow the arrow and find another route. Do not stop or cut across a solid line.
6. Summary Reference: Transverse & Area Pavement Markings
| Marking Type | Graphic Appearance | Location | Mandatory Driver Obligation | Prohibited Driver Behavior |
|---|---|---|---|---|
| Transverse Stop Line | Solid white line across entire lane | Signalized junctions, stop signs, rail crossings | Bring vehicle to a complete standstill behind line | Overhanging, crossing, or straddling stop line |
| Give-Way Line | Dashed white line across lane + inverted triangle | Minor road entries, roundabout entries, merges | Decelerate, scan, and yield right-of-way to cross traffic | Failing to yield to priority cross-traffic; forcing entry |
| Pedestrian Zebra Crossing | Broad white stripes across carriageway | Mid-block crossings, school zones, intersections | Decelerate; yield absolute right-of-way to pedestrians | Overtaking within 30m; parking within 3m of crossing |
| Yellow Grid Box | Diagonal criss-cross yellow lines | Central intersection conflict box, fire stations | Enter only if vehicle can completely clear the exit | Entering on green light when exit lane is blocked |
| Directional Pavement Arrow | White arrows (straight, turn, or combined) | Intersection approaches, lane-drop tapers | Must follow the maneuver indicated by the arrow | Turning from straight lane; cutting across solid lines |
A driver approaches a signalized intersection with a green traffic light, but traffic beyond the junction is congested and stationary. The intersection contains a painted yellow diagonal grid box. What must the driver do?
Proceed into the yellow box and wait behind the car ahead since the traffic light is green
Sound the horn to alert traffic ahead to move forward before entering the yellow grid
Enter the yellow box at a 45-degree angle to leave space for crossing motorcycles
Halt before the intersection stop line and wait until the exit lane is clear before proceeding into the junction
Under sections 46 and 70 of the Land Traffic Act, what are a driver's duties when approaching a pedestrian zebra crossing?
Maintain cruising speed and flash headlights to warn pedestrians that motorized vehicles have primary road rights
Reduce speed, yield absolute right-of-way to crossing pedestrians, and refrain from overtaking any vehicle within the crossing zone
Stop only if a pedestrian is accompanied by a traffic officer or school crossing guard
Overtake stationary vehicles quickly on the left side to minimize pedestrian waiting times
At an intersection controlled by a stop sign and a transverse solid white stop line, where must a driver bring their vehicle to a complete halt?
Past the stop line with the front wheels inside the intersecting pedestrian crosswalk
Parallel to the stop sign post on the sidewalk regardless of where the line is painted
Entirely behind the transverse solid white stop line without allowing any part of the vehicle to overhang
In the middle of the intersecting cross-street if no approaching traffic is visible
Sections you finish are checked off in the contents.