who was in the wrong here (driving, with diagrams)

[redwednesday]

So two vehicles, a car and a van, were exiting from a petrol station car park - a purple transit van and a red city car.

The red car is turning right and the purple van is turning left. The red car pulls forward to go as the way is clear but then the purple van pulls forward, blocking the view of the driver of the red car who can no longer see to the left. The driver of the red car is now partially in the road having started their right turn but can't complete the turn because they cannot see to the left. They know it was previously clear and so started their turn but can't be sure that another vehicle hasn't pulled out of a side road further down to the left.

who was being unreasonable? and what would you have done if you were either driver?

What ever happens if you can't see and hit something it is your fault.

If a car had pulled out of the side road, then there wouldn’t have been a collision considering they pulled out the same time and driving at roughly same speed. It sounds like red car had already made a judgement and started to manoeuvre before the van had set off, so I can’t see a problem.

Red car shouldn't have entered the road at all until they could see it was clear. As it was, if they were no longer sure it was clear, they should have checked their rear vision mirror and reversed back out of the road. If they had stopped at the kerb and then the purple car had pulled alongside blocking their view then they would have been safe to wait at the kerb, not half in the road.

If the car driver has seen the road is clear and made the decision to go, it's best for them to carry on and make their turn.

If they were just inching forwards to get a better view, they should have waited until they got that better view. (And they've inched too far forwards, but that happens, they can always reverse if need be.)

They were idiotic. So at that point, they were in the wrong. Before then, neither of them were

"If they started the turn knowing it was clear, they can continue with confidence."

^ This ^

The time it takes between starting and finishing to turn right on a normal road is a second. No car could be travelling so fast as to turn a previously clear road into anything near a collision risk.

I depends how long they dithered and how close the nearest side road was.

Why would the red car start to pull out if they didn’t know for certain it was clear to the left?

Surely they’d ascertained the road was clear before they began to pull in to a live lane?

Ergo, they should have been safe to continue. Their view suddenly being obscured by the van is irrelevant, had they been vigilant drivers.

This happens all the time at the end of my road. I'm usually in the lane to go left and I only need one side of the road clear. Whilst I try not to block the vision of cars to my right, I shouldnt have to wait until both ways are clear to turn left. There is enough space for two cars. When I'm turning right I wait until I know both lanes are clear and don't pull out until I'm confident that I can pull out safely. You sound like a nervous passenger and probably made the situation dangerous if you made the driver doubt their intentions. Unless they have a history of pulling out randomly then trust their driving.

I'm with @Walkingdeadfangirl and @Winterwoollies on this one. If they'd started the manoeuvre, the movement of the van should make no difference.

The implication of the OP's approach seems to be that if there were no van, there's a possibility of the red car seeing it's clear both ways, getting halfway across the road then suddenly seeing a car emerging on to the road from the left and stopping to let them pass! Let's hope nothing comes from the right while you are suddenly frozen like that...

As that shouldn't be a possibility when the van is absent, it shouldn't be a possibility when the van is present.

I would have waited if I was red car.