The city to the rescue.
But now, the city has fixed the median strip, adding a big sign and a bunch of yellow plastic bollards. I had emailed Councilmember Nadeau and ANC commissioner Kent Boese about it, and they responded quickly and got in touch with DDOT and other agencies, who fixed it within the week.
Nice to see this, and goes to show that emailing your elected officials can help!
Here's another photo of the result, and the before photos.