I'm posting here mainly to get the traffic, so I expect a wide range of robust responses 
About this time last year I started a thread about a time when I nearly ran over a small toddler I found wandering in the middle of the street near where I park for work. Here's the thread:
www.mumsnet.com/Talk/am_i_being_unreasonable/1438862-What-else-could-I-should-I-have-done-for-this-child
Brief summary - I couldn't find an adult in sight and didn't know which house he came out of, but then a teenage girl turned up who said she knew him and I left him in her care.
The majority view seemed to be on that thread was that there wasn't much more I should have done at the time. A few people thought I was being judgey, which I may have been.
Well more things have happened. I guess you don't forget the face of a child you nearly run over, and I have seen this small boy now on a few occasions and know which house he lives in. The first thing that has been concerning me is that for several months now, there has been a broken beer bottle on the front step coming down from the short path from their front door to the pavement. The broken glass has been there for literally months. Nobody has cleared it up, and still I see the boy, his mother and older siblings coming out of their front door regularly.
Then today I was walking from my parking space to work when I suddenly saw the child run straight across the road, alone, again no adult in sight. The front of the house faces onto a busy main road, with a primary school opposite so around 9am there are always lots of cars, plus the road is a bus route and about 100m away from a junction with the city inner ring road. Myself and a few other women saw him run across the road and we stopped to see if his mother was around, possibly just dropping off older children at the school opposite the house. She wasn't; the front door was wide open. Another woman who had been dropping her kids off at the school then came along, recognised the boy and took him back across the road to his house where his mother came out and yelled at him for being naughty.
So basically that's twice I've witnessed this boy being able to get out of his house unseen and run across a road, the second time a much busier road, and it's been up to passing adults to take him back to safety, plus there's the broken glass still on his doorstep.
So what would you do? Is this the point where I should call SS, or should I decide it's none of my business? All views appreciated, because I can't stop thinking about it.