[Editor's note: this is the second in an occasional series written by Alan Durning, head of Sightline think-tank in Seattle. He and his family are living car-free for a year, and he's writing a series about how they're faring.] When my family decided in March not to replace our Volvo for at least a year, we were mostly thinking about the practical implications. We were thinking about pollution, of course, but also about dollars and safety and bus routes and walking distances. What has become evident a few months into this adventure is just how much our cars equate not just to money saved or spent but also to cultural currency. Even while we're saving bundles of cold hard cash on gas, insurance and upkeep, hidden costs have emerged in a social barter system that, like much of our culture, is car-centric. We quickly collided with the face of the car economy: other parents. Driving gifts The thing about parenting is that it's best done in groups, so you can share with others. This sharing operates largely on the gift economy. That is, parents do favours for each other. The most routine favour they give -- the currency of parenting -- is the ride: I give your kid a ride to practice; you give mine a ride home. You bring your kid over to play; I drive her home again. The swapping of rides is a convenience and a practicality, of course. But it's also a form of community building. In fact, anthropologists regard the reciprocal doing of favours as not just a form of community building but as the essence of community building. That's because humans, like other primates, seem to be programmed to honour the norm of reciprocity, which Stanford social psychologist Deb Gruenfeld defines as "a powerful and pervasive social rule that compels us to treat others as they have treated us. For example, when others have done us a favour, we feel that we 'owe' them one in return." When the bonds of mutual reciprocity are thick and stretch in many directions, you have a strong community -- one that's high in social capital. And you've got the feeling, as a parent, that many hands are there to support you. People chip in to help you when bad luck strikes, and you do the same for others. Uh oh But subtract the car from this equation, and you're suddenly out of currency for the most basic exchanges. When we first went carless, for example, Amy and I found that our pre-existing credits -- favours we'd done over time -- all came rushing to our aid. Our community aimed to rescue us from carlessness. One family offered: "Do you want to take our second car for a week or two?" One family contemplated giving us an old car they'd inherited. Then, after we declined these offers by explaining that we have FlexCar when we need it and that we're figuring out ways to live without driving much, reactions differed. Some families have stepped up, hero-like, and insisted on doing all the driving themselves: "You shouldn't have to pay for a car just to take the kids to rehearsal. I'll drive both ways. I don't mind." But we don't want to accept favours that we can't reciprocate. We don't want to accumulate social debts and feel beholden to others. And we suspect that such heroism would lead to resentment and withdrawal before long. Transportation pariahs Other families -- more of them -- have pulled back, uncertain how to interact with us because we don't hold the currency. They become a little shy toward us, a little awkward. And feeling this way, they often take the path of least resistance, which is to swap rides with someone else instead. Sadly, that leaves us, and our kids, out of the community. To guard against heroic over-giving and shy withdrawal, we have been trying to become more assertive about alternative exchanges, bartering child care and other favours for rides when a ride is necessary. And this assertiveness typically works -- when we can muster the courage to take such social risks. Despite the ambiguity (how many hours of child care are worth one ride to a sleepover?), other parents are receptive to other forms of exchange, and these more complicated exchanges build community just as quickly as ride swapping. Lacking a car, Amy and I have been forced to do more asking and more creative reciprocating. This necessity has become a virtue: more community, more time with neighbours. In fact, renegotiating the social side of the car economy, and adapting to life with no cultural car capital, we've found new -- enjoyable and enriching -- ways to experience and engage with our communities. We have discovered that without our car, we spend more quality time with our own kids and with groups of their friends because of creative carless favours. We enjoy more activities that are around the corner rather than across town, which means supporting community businesses and services and keeping our neighbourhood vibrant, bustling and safe. We now see other parents as more than just mini-van drivers -- we actually interact with them more. We like this new barter system! And we're not the only ones who have noticed the benefits. One of my wife Amy's buddies remarked to me, "I love that you don't have a car. I see Amy a lot more." They get groceries together. The friend drives; Amy buys the lunch. They both enjoy the outing. We're not saying everyone should scrap their car. But reducing car travel and insisting on complete, compact communities instead of poorly planned sprawl can actually save people time in traffic and can lengthen their lives -- by staving off crashes (the leading cause of death up to the age of 44 in the Northwest); encouraging regular walking (reducing obesity); and clearing the air of toxic pollutants. Our carless experiment has revealed new ways to enjoy our neighbours and strengthen our neighbourhoods. Rather than losing on the exchange, we are building communities that nurture our kids as they grow up. At the same time, we're investing in our kids' futures.