Yup, MF has 4 blocks -- station, lift, course, unload station. This allows them to safely run 3 trains.
As RideMan said, you can never allow two trains to EVER occupy the same block. This means you need (at least) one more block than train, so that you always have an open block to advance a train TO.
For example, with a train on the MF course, you can send another up the hill, then advance the one in the unload station to the load station before the one on the course makes it back. You can't allow the one on the hill to go OVER the hill until the on-course one is back in the unload station. Lather, rinse, repeat.
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--Greg
http://www.pobox.com/~gregleg/