Wanted: a hint (not a walk-through) for the Trainyard level called A Barrel Roll

I've been playing Trainyard on my iPhone. I'm having fun. But I've reached A Barrel Roll and I'm not getting past it. I can get the cars down to two purple and two green but I don't have enough free space at that point to work out a merging pattern to get them down to one of each. I started over and tried to work out a system of pre-merging the blues, reds and yellows but then I didn't have enough space to do a final merge. And I don't really know what to try next.

There are places I can watch a walk-through and places that will just show me a winning screen. And I could move on. but if anyone here plays that game and can give me just a nudge in the right direction, I'd rather go that route.

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Yes, that one is difficult.

You just want a hint, so it's hard to say exactly how to provide a good answer to your question. But here goes.

Hint #1

My solution involves first getting 4 Green and 4 Purples, not pre-merging the primary colors.

Hint #2

Split them up so the Greens go to one side and the Purples go to the other.

Hint #3

Focus on either Green or Purple side for your solution. the other side can be a mirror image (or rotation) once you work out a solution for the other side. You only need half the map.

Hint #4

My solution involves 3 merges each: 2 on the top merge, then 2 on the bottom merge, then the results merge.

Hint #5

Your first 2 merging stations (to go from 4 to 3 and 3 to 2) should only take 4 tiles total - a small loop that goes away from and then comes back to a track. This is because the trains are only 2 tiles apart.

Hint #6

All 3 of my merges on each side are within 1 time increment of one another (a time increment defined as how long it takes 1 train to move 1 tile).

Hint #7

I'm running out of hints here without showing you a picture.

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Thanks! I don't have time to try it now but I'm making a point of not reading the hints so that I can try it out with as little info as possible. That kind of staged response is perfect! – clweeks Oct 22 '10 at 20:02