I assume you mean the Walthers traffic light controller. This unit is meant to drive LEDs. It has built-in current-limiting resistors so that none are necessary for the LED traffic lights. Not only does that make them impractical for driving 12-volt bulbs, it probably makes them unable to drive a relay. There may be a relay that would work with this unit, but I wouldn't get my hopes up.
It takes an iron man to play with a toy iron horse.
It sounds like you don't have enough power to run the light. So a relay makes sense, but will require an external power source also. Relays are available at. Just match the voltage and amp requirements.
http://www.allelectronics.com/
And other places.
Richard
I have the walthers switch machine, but have N scale traffic lights that run on 12v. the walthers switch machine puts out only 1-2v. Is there a relay that can be used? or maybe a transistor that i can use to transfer that 1-2v into 12v. Thank you.