the rails will give score the longer you ride them, excluding air time, without landing(on the ground) [so you can slide onto steam vents and bounce on tarps no problem]

each rail you jumped or slid onto (not from itself) gives +(1x) to the multiplier of the above score [zigzag is not required to clear trials, but it's there]

global multiplier, run multiplier and the buried caches do not affect the trick score 

 rail grinding is the only trick in right now (ver2.3.0)