take a look at the turnout. the frog is actualy one cast conductive piece. it is isolated from rails but if you choose so you can route a wire to it and power according to the position of turnout. so shorter engines like 0-4-0 docksider or old B switcher will not stall . or leave unpowered for "insulfrog" opetation.
snap switches have to agressive of diverging route to my liking