BLOCK SECTIONS activating when no train in the next block
Hello!
The brakes in NL2 are by default set to lower a ride's speed to a certain speed limit. If you want to only have the brakes activate when a ride is emergency stopped, you can set this speed limit to be higher by selecting a brake piece and going to Track -> Type Settings.

I'm not sure I quite understand the second problem though. Do you mean a train valleys at the bottom of the valley immediately after BB2, then when another train passes by BB2 it crashes into the valleyed train despite BB2 supposedly being there to stop the train? If so, I would increase the length of BB2 so that it can stop trains in case of an emergency.
Thank you so much for your reply - those settings in the image make so much sense, thank you!!
As for the collision - it occurs at BB2 as the first train is stopped (having the original speed of braking I had) and then the second train collides at the top of that hill where the brake section BB2 is - but I don't understand why becuase surely at BB1 the train should realise there is a train in BB2 ?
Thank you again
Hmmm, I'm not 100% sure in that case, unfortunately. One reason I think could be causing the issue is that BB1 is both short and close to the lift, such that when the ride is commanded to stop at BB1 it keeps going. The lift block might only be seeing that BB1, the block directly in front of it, is free, and not that BB2 is occupied, so it keeps pushing the train through BB1 even while BB1 is trying to stop the train? I'm not sure if this is the case, though, since your trains seem to be short enough that this might not be the issue.
Maybe try increasing the length of BB1 or increase the distance between the lift and BB1? If those two things don't work, maybe increase the deceleration? Unfortunately I'm not fully certain if any of those will work, sorry. :(

Hello, can someone please help me in my first no limits 2 coaster
https://imgur.com/ZafNIwB
https://imgur.com/aAds39V
These two pictures show the issue I am having - I have two trains on the track, and greater than 2 blocks (as per block theory). For some reason the block brakes are activated when not needed (no train immediately after that block) as seen in image 2. I cannot understand why the brake is activated when it clearly does not need to be. And to add to it when I let it run automatically the 2nd train will collide at the top of the hill in image 1 despite the blocking.
Any help will be greatly appreciated