During my trip into the park this past weekend, I made a rare visit to the valley. Though things were signed properly, it was still a bit strange and un-nerving that there was two-way traffic on both sides of the valley (North and South Drives). Luckily, traffic wasn't that heavy (got there early evening, 6PMish). Thus the two-way traffic and several detours. But it's the right time of year to do this.
https://www.nps.gov/yose/planyourvisit/roadwork.htm