Route your belts freely underground. Thats just an updated Version from the Original from Therax. I made if compatible with Space Age with the help of a cool guy from the Factorio Discord.

All credits goes to the Original: https://mods.factorio.com/mod/beltlayer and "fgardt" from the Factorio Discord who helped me greatly getting this work done.

MAY STILL HAVE SOME BUGS !