1.3 Roundabouts and Yellow Junction Boxes
Key Takeaways
Roundabout traffic in Sri Lanka travels clockwise, keeping the central island on the driver's right.
MNS-09 Compulsory Roundabout requires entering vehicles to give priority to vehicles from the right at the give-way line (RM-02).
Lane arrows painted on the approach (RM-23 to RM-26) are orders; follow them when choosing your roundabout lane.
Do not enter a yellow junction box if any part of your vehicle would have to stop inside it because of other stationary vehicles.
Exception: a right-turning vehicle may wait in the box when held only by other stationary vehicles waiting to complete a right turn; boxes are never used at roundabouts.
1.3 Roundabouts and Yellow Junction Boxes
Roundabouts and junction boxes manage busy junctions without full traffic-light control, and both appear on the DMT sample paper. One question asks for "the basic rule of a roundabout" (give way to vehicles coming from your right). Another asks when a driver may enter a box junction.
1. The Legal Rules for Roundabouts
| Source | Rule |
|---|---|
| DWS-25 Roundabout Ahead (Schedule I) | A junction ahead with a circular central island; traffic moves round the island in a clockwise direction |
| MNS-09 Compulsory Roundabout (Schedule II) | Vehicles entering must give priority to vehicles from the right at the give-way line (RM-02), or at the junction if the line is not visible, and then go round the island |
| RM-02 / RM-37 give-way line and triangle (Schedule V) | Do not cross the line in a way that endangers traffic in the roundabout or forces it to change speed or course |
| Section 148(13) of the Act | When turning right at a junction with a structure in the middle, complete the turn keeping the structure on your right |
Together these give the core rule:
Approach slowly, give way to traffic coming from your right (traffic already circulating), enter when there is a safe gap, and travel clockwise with the island on your right.
The junction-box rule does not apply at roundabouts. Regulation 27(12) says junction boxes are placed at junctions "other than a roundabout".
2. Approaching and Entering
- Read the signs early: the yellow DWS-25 diamond, any direction board, and the lane arrows (RM-23 to RM-26) painted on the approach. A lane arrow is an order.
- Slow down in good time and check your mirrors.
- Look right. Traffic already on the roundabout, and traffic entering from the approach on your right that will reach your path first, has priority.
- Stop at the give-way line if necessary. Do not edge forward into a gap that forces a circulating vehicle to brake.
- Enter smoothly and keep the central island on your right.
Large roundabouts in Colombo and other cities carry heavy traffic, including buses and lorries that need more room. Do not ride alongside a large vehicle on a roundabout, because it may need to cut across your lane.
3. Choosing a Lane and Signalling
The 2015 regulations do not prescribe a lane for each exit. Follow the lane arrows and direction signs where they exist. Where there are none, the widely taught method is:
| Where you are going | Approach lane | Signal on approach | On the roundabout |
|---|---|---|---|
| First exit (left) | Left lane | Left | Stay in the left (outer) lane; keep signalling left and leave |
| Straight ahead | Left lane (or as the lane arrows show) | None | Signal left after passing the exit before yours |
| Right turn, or later exits | Right lane | Right | Circulate near the island; signal left after passing the exit before yours, check your left mirror and shoulder, then move out |
| U-turn (full circle) | Right lane | Right | As for a right turn, signalling left after the exit before your return exit |
Signals must be given with your electric indicators (s.153(1)). Use them so that others can predict your path. Cyclists, three-wheelers and slow vehicles may stay in the outer lane even when going all the way round, so give them room and do not cut across them when you leave.
4. Junction Boxes (Yellow Criss-Cross Markings)
A junction box is a yellow-bordered area filled with yellow criss-cross diagonal lines (road markings RM-46 and RM-47), placed by the road authority to keep a busy junction clear. Schedule V states the rule:
A vehicle must not enter the marked area in a manner which causes any part of the vehicle to remain stationary within it because other vehicles are stationary, provided that vehicles turning right may wait within the area when prevented from proceeding only by other stationary vehicles in or near the area waiting to complete a right turn.
What this means in practice:
- Going straight or turning left: enter only if your exit is clear and you can drive straight through without stopping. A green light does not give you the right to enter a box when the road beyond is blocked.
- Turning right: you may enter and wait in the box if the only thing stopping you is other stationary vehicles waiting to complete a right turn (in practice, a queue of right-turners held by oncoming traffic). If your exit road is blocked, do not enter.
- The box works together with the lights, signs and other markings at the junction and does not override them (regulation 27(12)).
+------------------------+
|\ /\ /\ /\ /\ /\ /\ /\ /| Yellow junction box (RM-46 / RM-47)
|/ \/ \/ \/ \/ \/ \/ \/ \| Enter only if you can leave without stopping,
+------------------------+ unless you are turning right and waiting only for
other vehicles waiting to complete a right turn
The DMT sample paper's box-junction question offers four answers: "if you are going straight ahead you may enter the box", "except when turning right, you must not enter the box if your exit road is blocked", "except when turning right, you may enter the box at any time" and "you may enter the box at any time". Only the second matches the rule: apart from the right-turn exception, never enter a box unless your exit is clear.
5. Common Mistakes at Roundabouts and Boxes
- Entering a roundabout without looking right because "the road ahead is clear". Priority is to the right.
- Driving round the island anti-clockwise, or cutting across its left side. Keep the island on your right.
- Stopping in a junction box because the traffic ahead stopped. Wait behind the box until your exit is clear.
- Leaving a roundabout from the inner lane without checking the left mirror and blind spot.
- Treating a roundabout entry as a STOP junction. You need not stop if there is a safe gap, but you must give way.
What is the basic priority rule when entering a roundabout in Sri Lanka?
Give way to vehicles coming from your left
Vehicles entering the roundabout have priority over vehicles already circulating on it
The largest vehicle always has priority, whichever direction it comes from
Give way to traffic coming from your right, already on or about to cross your path
You are going straight ahead at a junction marked with a yellow criss-cross junction box. Your light is green, but the road beyond the junction is queued back to the box. What should you do?
Enter the box and wait inside it, because your traffic light is showing green
Wait behind the box until you can clear it without stopping
Enter the box only if you sound your horn first
Enter the box, because junction boxes apply only to right-turning traffic
In which direction does traffic travel around a roundabout in Sri Lanka?
Clockwise, keeping the central island on the right
Anti-clockwise, keeping the central island on the left
Either direction, depending on the exit you want
Anti-clockwise on single-lane roundabouts and clockwise on multi-lane ones
Sections you finish are checked off in the contents.