Kwakka Jack,
You are on an advanced driver forum... Why would you want an answer from a non advanced driver point of view?
I am more than willing to give all the help and assistance I can, but when you create a problem/change a scenario from a not very well written book and expect a non expert answer, I wonder if you have missed the boat.
What should occur in that scenario is You are V3 in Lane 3... at 70MPH... Looking as far ahead as you can see, looking for other potential hazards ahead of the slow moving van/HGV in lane 1. watching closely what develops between V1 and V2 driving abreast and at the same speed with V1 on a closing gap with the HGV, taking no avoiding action like slowing down then pulling out behind V2 to avoid a collision etc...
You should be checking your mirrors to see if there is anything coming up behind you which might require you to change your plan... Covering the Horn and Headlamp flasher, as you pass the slower vehicles in the inside lanes and, when safely past, move back to lane 1 unless, there is a further hazard ahead which would prevent you from returning to the left...
Then you can think, when safely past, what on earth were those two bulkheads doing back there... why don't they look further along the road, observe and anticipate what will happen and then take the necessary action to avoid being caught up in a potentially dangerous situation... just like I have done...
And before someone says 'but you have been in a line three abreast', the system IS flexible, the differential of speeds would mean you were along side for a very very short period of time.
After all, where is the safer place to be? Ahead of a hazard behind you, or driving more slowly, possibly putting yourself into conflict with V1 and V2 and getting into a possible conflict with other vehicles approaching from the rear, because you are not traveling at the national speed limit in the outside lane of the motorway?
FF
)
