The method of transportation influences coincidental interaction.

When an afterschool program ends I often see parents wait in their cars to pick up their kids. With cars lined up one after each other parents don't get the opportunity to see and chat with other parents they know. This problem simply wouldn't exist if everyone was on foot.

Imagine how much more connected a school or afterschool program might be with parents that have a chance to chat every day or every week rather than hardly at all.