Caltrain????

Question

why are there different zones listed here http://www.caltrain.com/caltrain_map.html

Do you have to pay everytime you leave A ZONE?

Answer 1

No.

You buy one ticket before you board - they are sold out of vending machines on/near the platform.  The machine will ask you what zone your destination is within.  The cost of your ticket will depend on how many zones it takes to get to your destination.  You keep the ticket with you while on board the train and present it to the conductor if he asks.  

The fares for Caltrain are listed here:  http://www.caltrain.com/caltrain_zones_0...

Answer 2

The amount you pay is based upon how many zones you wish to traverse on your trip.

Then again, you can wait for one of the newer 2 level train cars, and then play a game of upstairs/downstairs when the conductor comes to validate your ticket.  Just make sure you can run fast!