Somewhat inconsistently. This was most obvious on a pair of one-way streets, but one of them has been returned to two-way traffic. AFAICT, the waves in opposite direction started at the same time and the two streams passed each other around the halfway point. Other one-way streets in the area aren't on precisely the same schedule. The stretch was only about six or seven blocks long. And the wave didn't start at the boundary street of the area on one end, but one block into the area.