This is a very interesting question. It has come up again recently. Use of the track is changing. As of December 1 2010 all users must have authorization.
Fill out the forms. Take them to Julie Naylor in the Maintainence and Operations Shack. It is behind Crest School. You can park behind the Administration Building off 42nd, next to the bus storage area.............After December 1 2010 you will need to be checked out and issued a gate card to enter, as the gates will be locked.
You are only allowed to use the track if no other scheduled activity is going on.
Complicated but I hope that clears things up.