TMR put this up on their Facebook asking who has to give way, but that’s too easy. A much more complicated question is: what does the law say around indicating?
I’ve seen people say only blue must indicate, others say both must indicate, and yet others say neither must indicate. Which is correct?
Which clause there would compel the bike to indicate?
2 d) / 3 d) are “entering a marked lane, or line of traffic, to the left/right” but this line is directly ahead of the bike.
So in your interpretation, when two lanes merge, whether or not indicating is required would depend on the precise configuration of the lanes? For example, in my experience a road shaped like the above would be more likely to have the left lane end; the “two lanes merge into one” scenario more often places the line down the middle, like this:
In that scenario, would only the left, neither, or both be required to indicate, in your opinion?
edit:
one other thing worth considering…the motorbike in the image actually won’t be legally allowed to keep its line straight. When there is only one lane in each direction, road users are required to “drive as near as practicable to the far left side of the road”. By driving directly down the centre of the lane, a motorbike is probably not doing this. So it will need to move left, under the law.