“is there DC alley etiquette (or even laws?) that cars should honk as they drive through alleys or as approaching intersections in alleys?”

“Dear PoPville,

Yesterday afternoon I was driving through an alley on the regular school-designated route (in blue) to pick my kid up from school. I was driving about 10 mph. As I was driving, a bike (in purple) turned the corner and very nearly hit the side of my car. Thankfully, the biker wasn’t hurt at all and didn’t fall of his bike. However, he was extremely angry at me,

pointing at me through the window and shouting. He followed me the short distance to my child’s school and continued to shout and gesture angrily (including flicking me off). I didn’t feel safe lowering the window, especially since my other two kids were in the car with me, but what he seemed to be upset by was that I hadn’t been honking as I went through the alley.

So my question is this – is there DC alley etiquette (or even laws?) that cars should honk as they drive through alleys or as approaching intersections in alleys? I’ve never heard of such a thing, and imagine it would generally be disruptive. But I’m curious if this is something I should start doing. I know bikes and cars are a hot button issue- I don’t frequently bike, but my husband does and I try to be very conscientious about bikers. “