Roundabouts and big junctions are where Vietnamese traffic rules meet Vietnamese traffic behaviour — and they are where most new foreign riders have their first close call. The law sets out signals and priority — traffic-light-rules-vietnam covers it — but junction craft is practical knowledge.
Roundabouts: yield, then flow
Approach ready to stop. In practice, traffic already on the roundabout usually has priority, but entry speed and eye contact matter more than theory. Pick your lane early: outer lane for the first exit, inner lanes for later exits — and signal your exit. Locals treat roundabouts as merges rather than strict priority zones, so move with the flow rather than asserting rights.
The invisible lane
At big junctions, expect motorbikes to gather in front of cars at the stop line, filling the shaded box area — then flow away from the line in all directions when the light changes. That first ten seconds after green is the risk window: bikes fan out across the junction, and turning cars cross through them. Wait a beat, watch the front wheels around you, and exit through a chosen gap, not the middle of the swarm.
Turning right
Right turns are their own game — including the unusual signal-governed right-on-red case covered in right-turn-on-red-vietnam. Always check left before a right turn: bikes overtake on both sides here, and the one coming up your inside is the one you cannot see.
Junctions without lights
The working rule is big road first, slow everything else: make eye contact, move predictably, and never accelerate through a gap a bus could also take. Defensive-riding-motorbike-vietnam generalises the mindset.
The one-line version
Yield on entry, pick your lane before the roundabout, give the first ten seconds of green to the swarm, and always check left when turning right.