A puzzle challenge with my kids toy train set (that I can't solve)

My 2yr old son has a simple toy train set and we like to build tracks. I've been thinking about building a track according to two rules:

1) the train must be able to go on in an indefinite loop (if the batteries had unlimited power)
2) in a full loop every part of the track has to be passed (at least) twice: first one way, then the other way 

This means I can't just build a circle, or some other simple lineair shape where begin and end are connected. Because while that would create an indefinite loop, it wouldn't pass rule two as the train always passes the track in the same direction. 

So we need switches. The switch is a Y and if the train comes from the stem it will go in the way the switch is standing (see yellow arrows). If the train comes from one of the 'arms' of the Y the train will push the switch over (see grey arrows), depending how the switch is standing. Next time the train comes up from the stem the train is diverted in the other way. 

 This may sound complicated in words, but I have solved the most simple solution for this problem. With just two switches I can build this:

(video doesnt embed because it's a 'short'?) 

It's an indefinite loop AND every inch of the track is passed at least twice, in both directions.
Also there you can see how the switches work. Pretty simple.

What I've got:

- 6 switches
- 2 bridges 
- lots of rails, straight and curved

The question that bugs me: is it possible to build a track that follows rules (1) and (2) with 3 or more switches? I've been building traintracks while my son was in bed and my wife makes fun of me. Would be great if you guys can help me sort this out. I will make a video of plausible solution you propose.

Here's a photo of the bridge. Only one track can go underneath. 

Thanks 🙂 I hope some bright minds here are able to come up with a solution as well!