it seems to be dependant on what mode you are on (50, 100,150 cc) but even than it doesnt seem to always work. 50cc seems to be drifting while passing thru it and the rest i have forgotten

for me drifting through it worked for 150cc as well, but it might've been a bug then

the game tells you what every item does in the menu, but nobody ever goes through the trouble of looking there, do they? you can also go around them (if there's enough clearance on either side of the track) or just hop over them with a spring

I could be wrong but from my experience you can just hop, by starting a drift, and you will go right through them. They should turn green or something. Its been a while but I plan on returning lol

when the rays turn green that means you got the 1 in 3 chance for it to be friendly, see otaku's post.