It is a chestnut of urban planning that a neighborhood must have a certain number of dwelling units per acre (usually around 8 or 10) in order to have adequate bus service. But the quarter-acre lot seems to get no respect: too dense for estate-home luxury, not dense enough to constitute "smart growth". But a 9 year-old girl recently taught me that, at least for children of a certain age, these medium-density neighborhoods have their advantages.
The girl belongs to a family I know that has embraced some of the strictures of traditional Judaism, including the prohibition against using most forms of technology (video games, computers, cars) on the Sabbath. This seems to work well for the older children (who spend most of the day sleeping). It also works well for their 6 year old daughter, who has little desire to leave the house for any reason as long as she has someone to play with. But the 9 year old daughter recently mentioned to me that she is (to put it euphemistically) not in love with Sabbath observance; I gather that she is bored because of the absence of video games.
I thought about this and asked myself: hey, wait a minute! Why doesn't she run over to a friend's house, as do children in my city's most Jewishly observant neighborhood? Perhaps density has something to do with it.
This family's neighborhood is mostly comprised of pretty large houses- lots of half-acre and one-acre lots, the odd gated community. Since there are lots of sidewalks, the neighborhood density is high enough for people to walk to synagogue and to walk to each other's houses on special occasions- but not high enough, I suspect, for 9-year olds to casually visit each other.
By contrast, most homeowners in my neighborhood in Jacksonville (as in Atlanta's biggest Orthodox Jewish neighborhood) live on quarter-acre lots. From the standpoint of an adult trying to use public transit, this area is still car-dependent sprawl. But from the standpoint of a preteen child who just wants to visit a friend in the neighborhood, the residential parts of the neighborhood are navigable on foot; my co-congregants' children visit each other's houses more routinely, and are thus presumably less lonely than my friend's 9-year-old.
In sum, the relationship between dense and not-so-dense residential neighborhoods is not a simple dichotomy (walkable vs. not walkable) but a trichotomy: very low density areas that are walkable (if at all) only for adults, medium-density areas where both adults and children can walk within the neighborhood, and more compact areas where people can easily leave the neighborhood by public transit.