Tim Darst began riding TARC buses at 6 this morning and was nearly done with his 12-hour marathon when I caught up with him at a stop at 4th and Broadway.

Darst is marking World Car Free Day -- which encourages people to give up their cars in recognition of their environmental impact. He's director of environmental group Kentucky Interfaith Power & Light. He estimates his trip has taken him 120 miles across the TARC bus network in his bid to promote bus ridership as an alternative to driving. At various points, he stopped for prayer with (among others), Roman Catholic Ursuline nuns, a Tibetan Buddhist teacher and, below, with Terry Taylor, director of the group Interfaith Paths to Peace. Taylor's prayer invoked traditions in various religions calling for responsible environmental practices. Darst said he also got into a spontaneous conversation about creation care with young Mormon missionaries on a bus ride.

Last year, Darst logged 200 miles on TARC buses, but "when you want to stop for prayer, you lose miles," he said.

The goal of the day is to remind people "to try to reduce our impact" on the environment and to "pray for people who are affected" by pollution.