unobstructing

“I am convinced,” he wrote in summary, “that a bridge suited to this great want spanning the Mississippi, at an expense much less than has already been made, almost if not entirely unobstructing navigation, could years ago have been completed, upon designs well-known and tried in this country, had not the authors of the present monster stood in the way.”

The Great Bridge David McCullough 1972

Any lumber-yard or any tenement sufficiently dilapidated would serve as a model; and the fact that in the shifting architectural life of New York the actual original scenes of the incidents had been demolished and built upon by new apartment-houses, or new railroad stations, or new factories seventy-five stories high, was an unobstructing triviality.

T. Tembarom 1913