WASHINGTON — Routine sign replacement above an orphaned freeway in Foggy Bottom uncovered a roadside relic Thursday morning, evoking memories of an ambitious and contentious era in highway design.Cones were in place and two left lanes were blocked by 10 a.m. on the Interstate 66 Potomac River Freeway. Road crews with grinder saws and hammers were lifted by bucket trucks up to a weathered overhead structure behind the Kennedy Center.As strips of rotting plywood were pried off the face of a nearly 50-year-old sign, the outline of an Interstate 695 shield and two white arrows came into view, indicating a...