When the noise continued unabated for a half hour Ziggy went outside to chat. Apparently they had to work on the water main now because otherwise they would need to stop the cable cars, which start running at 6 a.m. or so. But oh, they were done with the jackhammer now, would just be there doing their work until 5 a.m. or so.
That was about 20 minutes ago. They're still hammering away. I do love living in SF on the cable car line.