underway

As Minneapolis grew, the city demanded that M&StL construct "underways" beneath city roadways.

There are in fact many such subterranean underways in Germany, speeding traffic beneath bergs, burgs and villages and into and around and under big city downtowns ...

I had been the diving officer on three previous submarines, …, and was an experienced officer of the deck with many underways and landings under my belt on all three.