Board Thread:Questions and Answers/@comment-26123293-20150615223747/@comment-26123293-20150616210344

The answer is, "at level 298 you can buy Shivaji tower for 315 gems which increases you station's flag capacity to 25 flags. And at level 347 for 7,920,000 steel + 6,480,000 + cement + 6,120,000 plastics  you can buy Aerial Tower II which increases station flag capacity by 5%. (I think that means an ultimate total of 30 flags). Verify this by going to the shop, click on buildings, scroll right as far as possible and the buildings mentioned above are listed, along with two that increase passenter limits.