O.K. I put all the curved pieces together and from outside to outside it measured 26  1/2 inches across.  But this still does not help me are tell me what type train I need to buy.  So sorry to seem so dumb but I know nothing about trains except that I want one for this track and don't want to buy the wrong size and then it won't work on the track. Thanks for everyone's help.

I  live in the country boonies. No train places around.  This is a very small track only consist of 8 curved pieces and only 4 straight pieces.  I want to buy a train online to run on this track. But I do not know what kind to buy.  Thanks.

Not sure what you mean by curve of the track. I am wanting to know what the scale is so that I know what type train to buy. Thanks.

I have a vintage metal train track. The track has 3 rails and measures 1  5/16 inches between the outer rails. This is measured from inside to inside. Can someone please tell me what scale this is so that I might be able to purchase a train for this track. Thanks for any help.