The train can leave the station but can't crest the lift until the train ahead passes through the mid-course brakes. Raptor and Batman have nearly identical timing this way.
You always need one more block than you have trains, and no train can pass in to the next block unless it's clear. With most three-train coasters, you have a scenario like this:
A - Station
B - Lift
C - First half of course
D - Second half
You could also factor in the final brake run on the B&M rides since you can put two trains in them. On said rides, optimal performance goes like this:
Train leaves station, climbs lift. Second train can leave when lift is clear, but may not crest lift until first train goes through mid-course. Third train can't leave until second train is through mid-course, which means that the first train has to be through the final brake run. If they're dispatching quickly on Raptor or Batman, a train will slow in the final brake run and gently roll right in to the station without stopping. I haven't actually seen this happen on Batman, but when guests are loading quickly and the crew is groovin' it happens on Raptor every day.
Maybe the easier way to explain it is that if a train approaches a block that is not clear, it's going to be stopped on the lift, brake run or whatever. So if Raptor rolled back in the helix, the train behind it would be stopped on the mid-course. If it rolled back in the cobra roll, the next train would be stopped on the lift. Get it?
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Jeff
Webmaster/Admin - CoasterBuzz.com