Retaining walls snap to pipes

You can run pipes into a wall then snap onto other side. This would enable you to dig close to buildings and cleanly bury pipes. Maybe the "usage rule" is that the pipe must cross straight across but heights don't matter. In this way you *could* provide a vertical splitter/merger alternative, maybe a cheat to cross pipes (unless it's pick a direction) or just a decorate pipe support without new game assets.
It would be a great pair with rules for burying pipes... You can drive megas or build structures on a full block down maybe at a half block smaller vehicles can pass.
Another suggestion... vehicle storage. Either warehouse/dock can take small vehicles at "500 quantity ea" or maybe add a civ building. I don't build up a fleet because then fuel and population are committed. I run into a snag and start salvaging.