1 - Select the 2D view in the “Shrink rings” panel in which the profile of the 2 tracks will be visible.
2 - Then draw the two profiles (separate objects) using bezier or mesh curves. For example, if you work in the XY view then each vertex of the profiles will be Y = 0.
3 - Now draw between the tracks the first object to be scaled (Eg a circle) assigning a name Eg myCircle. Then copy / paste manually or use the Array modifier all other objects so that each object can contain the 2 tracks. All other pasted objects will contain the first name. If the first one is myCircle then the others will be myCircle.001, myCircle.002 ... and so on.
4 - Now select the 2 profiles in object mode then select among the objects to be scaled only the first myCircle object that will be selected active.
5 - Send now the button "shrink rings" to get all the objects scaled on the 2 profiles.