The accident on 29 December could have happened along these lines. Just takes someone to cut in front of you to take out visibility of the road ahead...

http://youtu.be/SyiToW4NHqI

http://www.thaivisa.com/forum/topic/787670-indian-tourists-killed-in-van-crash-on-elevated-road-to-suvarnabhumi-airport/

Well, it's not convenient to water the grass / plants in the middle of the night with much less traffic and when one can see flashing hazard lights.

It's never a good idea, in my opinion, to be in the right hand lane when approaching a u-turn at high speed. I recall reading somewhere that it is infact illegal.

The practice is highly dangerous, there's no advance warning given at all. In the UK the whole lane would be closed off.

Surely can't be that big of a job to lay an irrigation pipe. It would only needing doing once instead of as at present watering every day for years.

The right hand lane isn't the fast lane and technically it's illegal to use that lane unless you're overtaking or using it to access a U-turn or right hand turn.

I'm not saying that having service vehicles parked or moving slowly in the RH lane without adequate warning signs/cones/lights is a wise practice.

I've learned never to change to the RH lane unless you have a clear view of what is ahead. On Suk in Patts they invariably have water tankers or gardeners working there, never mind the slow moving sidecarts that you just can't see if you have another vehicle in front of you wiping out the view.

Tip: If you're in the RH lane and the vehicle in front of you starts to change lanes to the left, don't even think about it - change lanes as well (or be prepared to brake). 80% chance he's changing lanes because there's something blocking his way such as cars waiting to U-turn, a water truck, a sidecart, or a vehicle coming in the opposite direction and doing a U-turn into your lane. And invariably they'll leave it to the last minute before they change lanes leaving you no time to see what's in front of you before its too late.