width and height of train rails

[Stress Tensor]

I'm just about to build out a rail network, and in hoping to avoid a major mistake (waste of time), I'm looking for suggestions for a standard for laying out the rails. I could use only two foundations, one for each direction, but that seems rather tight, i.e. I'm not sure whether this could cause problems on curves.

And even if only two wide could work, I'm wondering whether using three foundations would give me any more needed flexibility. For example, do people put anything in between the rails, e.g. additional power lines, lights, hypertubes, etc.?

Also, do people generally create multi-level structures which could contain roads or anything below or above the rails?

I know the answers could be "anything you want", but I'm just looking for what has worked well for people and what they recommend.

[Vectorspace]

I usually have 2 foundations, one per side.
The disadvantage of this is if you have a signal between the track for any reason (parallel tracks going the same way, left-handed track, bidirectional track) the signal won't quite fit and will clip into trains on the adjacent track.

[Rudal]

I haven't built a train network yet so I can't really comment on the separation of rails but when it comes to multi level structures I've watched this video and was blown away. :D

It's an old one but it still works. https://youtu.be/Ux7WC3wzTP8?si=QCQD80zFTDChYQvl

[Icepawthewolf]

The tracks can be easily centered on a single row of foundation, it gets a bit wobbly if not centered right at times. I've taken to building the stations on either five or seven blocks with two rows of this per station piece as best to keep it stable. Just make sure you keep track of the number of cars as each car can only pick up or drop off one item in bulk although I guess you could mix contents but the ratio would be odd. Make sure that each freight area is in the right part to unload the car that will be under it to make sure everything flows smoothly. Also keep in mind every time a freight stop turns on to load or unload cargo it'll use watts, the more active at one time the more watts used. Besides all that make sure you've got your station itself out front and all the cargo bays behind it as the engine leading the train is what stops at the station itself while the cars it pulls are everything behind it. A useful tip though is while build the train load excess building supplies on the cars of the train so you won't need to run back as often and also put a engine on the rear angled opposite of the lead engine so going back for resupply is easier. Oh and don't stop a train route between stations once you've set a time schedule as the train may get confused and try to go backwards instead of resuming going forward.

[Man's Best Friend]

Possibly more than needed, but I generally run rails with a single foundation separating them, with the actual rails centered on the flanking foundations. So my rail beds are 3 foundations wide. Seems to work fine.

[Stress Tensor]

Thanks for your replies everyone. After starting out with 3 foundations wide, I ended up redoing it with only 2 foundations, one for each direction. I found that I wasn't doing anything fancy with the middle foundation anyway, and given some of the tight turns and narrow paths, it became much more manageable being only 2 wide.

Oh and I finally gave up trying to be close to the ground. My rail network is usually between 20 to 50 meters (5 to 12 4m foundation heights) off the ground, sometimes more if I'm going over a ravine for short distances. Eliminates lots of tedious elevation changes without being too absurdly "in the sky".

(I mention this because I'm also curious how high other people build their rails)