Maximum distance from origin before things get glitchy

i am trying to make a 1:1 replica of a train line on roblox, and the length is 43.2km, or 142000 studs.

if i were to just build the whole line without scripting (each end of the line would be around 70000 studs from origin), would there be any glitches e.g. would the characters look weird, or the trains’ movement break?

or is there a better way of generating track for the trains to run along, which bypasses the distance glitch problem?

1:1 may cause lag due to the amount of parts, maybe 1:2 or 1:4 replica would go better with the Roblox game engine.

Also about origin lag, I think it should be ok if the 70k studs gets downgraded to maybe 25k.

A single-precision float (which is what I believe Roblox uses) only has about 7 decimal digits of precision. You should opt for a very small scale, or use programming to move the world relative to the client (on the client) to the origin.