1/24 scale is equal to 1/2" to the foot, G scale rail road which encompasses several scales including 1:20.3, 1/22.5 , 1/29, and 1/32 this is because all G scale uses the same track to represent different real life gauges.
1:20.3 would be 3' gauge but 1/29 would represent 4'-8-1/2" US standard gauge or 1:22.5 represent European meter gauge. Why all this train scale trivia? Knowing this will help you shop for bitz in the train section of the catalog, hope that helps out, I'll go back to lurking now.