Newman Atkinson says:

Gavin,
I had the same question from a fellow National Model Railroad Assn (NMRA) Same exact switch. First you need to sketch the rails out and meter what has contact to what rails such as the outer main rails and where they have power or ohms. On your switch the switch rails will flow power in the direction the switch is thrown. IF you are running different polarities on each main track In other words trains going in opposite directions then throwing both sides to the center crossing then there is a polarity problem when you cross the diamond. But if both tracks polarity direction are wired in the same direction. then it should not be a problem.. The diamond should wire to one switch through your switch motor such as a tortoise so the diamond track in that direction will get the power on each rail. The other switch power should stop at the diamond. It should measure that way with a meter.. You have 2 extra switch circuits on a tortoise motor and one can work the frog for that switch. That should take care of the frogs, That circuit for each frog power should have main feeds from the outgoing main rail from that switch. (The single track ) If I remember right on the one I helped with the outer main rail was cut half way between the two inline switches . That is because the shinohara individual switches direct the power to the switch direction and when that happens the non used side will actually short if a train crosses the gap on that outer rail. Shinohara 3 way switches will do the same thing. on my Shiohara 3 way switches I insulated both rails from the yard tracks and if I bring an engine past those insulators when the switch is turned away from that direction. you will have power from the opposite rail.on that rail So as long as your engine is sitting between the double insulators and the switch rails with the switch thrown away the you just have one side of the power getting to the engine. But when you throw the switch to align with the engine then you have both sides of the power and the engines run. Same thing will happen when you are coming down the straight on this switch. If you have the first switch straight but the second switch is turned when you cross the rail cut between the switches it will short.
For each main rail out your power for both rails should connect before the switch for each track.
that power should follow the direction to through the switch in the direction the switch is thrown.
Each direction of the diamond should wire to one switch matching rails from that main track. That power should not follow through to the rails past the diamond. For tracks with opposite polarity power on the other track, one side most likely will need to be on a reversing circuit to get the trains across the diamonds without shorting. That side should should run that block long enough to get the full train (with metal wheels to all clear the rail cut so it will continue on and switch back to the polarity on that side when it continues past the rail cuts for the next block.Actually if there is trains approaching different directions to this switch there should be 2 auto reverse circuits. If you labeled your drawing A and Btracks on the left side and C and D on the right side then you will need a auto reverse for track A and a second for track C (or track B and Track D if you put the auto reverser circuit board on the other side. On My layout I will have a two track each opposite polarity and it will be a single cross over. To Cross over to the other track the second track will need an auto reverse circuit. This is a lead to get over to the station platform track. After the station stop the train needs to cross back over to the other polarity so at the next cross over the switch will be insulated at that crossover again and the auto reverse will switch the polarity back on the run to go back to the original track. Actually my double track is actually a very long dogbone run and the return trip in on the other track. The section that needs the auto reverse can be done a head of the train with a manual double pole double throw electric switch. But for about 30 dollars for each auto reverse circuit it is worth the system to switch it over as you will find more times than not you will forget to throw that switch and your engine will short crossing the insulators or cut rail at each end of the block. But like I said it is much simpler if both main lines are in the same direction. But I don’t know your layout. Just follow your meter and it will be doing what I said it will be doing. Keep the diamond wired to one side or the other of your main lines. It should not be wired hot through that whole cross over rail (Switch to Switch) or to the other direction of the diamond. Each switch should stop continuity before it crosses the diamond from your main line track
In Review 4 tracks into the switches that means 4 power sources. None of them should power into the other switches. The diamond should be powered to one side of main lines and the other direction should not be powered to the opposite track of the diamond. Power your frogs from your switch motor of that switch and you should be insulated between all four switches including the cross over for that direction. Clear as mud right. This switch can be complicated or simple depending on your polarities. Even if this was four separate # 6 Shinohara Switches and a separate diamond in the middle the way it works is the same (only in this case does the diamond flow through power all the way on the diamond in that direction in which your track on one side of the diamond will need both rails insulated and that will go for the opposite direction track too. My diamond example here would be in this case an atlas diamond…….Thanks Newman Atkinson