Answer for Battleships Lieutenant Level 16

Here's my solution. Sorry for the blurry pic but you can make out what do.

My solution relied on three key facts:

• The 1st and 3rd trains, and the 2nd and 4th trains, can be combined. Like Alex says, you can't combine trains that follow each other directly.
• You can safely collide trains (head-on) BELOW the paint blocks since they'll get repainted the way you want as they come back north.
• You need two trains to end up blue, one red, and one yellow, so the blue paint block is key.

One other more explicit hint I can give is that in my solution 3 trains enter the YELLOW paint block going south, and one train enters the RED paint block going south.