Easy as Pi.
Reminds me of that tour of Nam. Man the company (wifey) and I were lucky to get out of Hue alive.


EDIT:
The thing I noticed (and have in Thailand and Nam) is that it at 1st seems anarchy to us westerners, but after a bit of examination - or time on a scooter - you realise the diff is it all relies on simple common sense.
Even most of the trucks give way if they think there
actually will be an accident, despite the fact they will come off best.
Nobody stops for long, no jams for long, lower overall speeds. Interesting.