Statues appearing after the start?

[hondaboyali]

Just a quick question, which I havent been able to find on the forum. On the more recent supercross tracks, rf tracks as well. Once the gates have dropped the tuff blocks (statues) appear at a set time in-front of the gates. I was wondering how this is done.
Thank you in advance

[Wahlamt]

It's done with a so called .seq (sequence) file.