Sorry, but mom gets severe blame from me. The stroller started to roll away several times, and she still did nothing to either keep hold of it or redirect it away from the platform edge.
The railway authority shares some of the blame because the platform slopes down towards the tracks instead of away from them. Rainwater and litter can be better controlled and cleaned up by flowing away from the tracks than towards them, and a secondary effect is that luggage, toys with small children chasing after them, and baby strollers do not gravitate towards the tracks.
Note to parents: Find out what brand that stroller was and get one for your youngsters. It apparently held together enough to protect the baby while being dragged underneath the train for 30 yards.
stay safe.
skidmark