The church basement air ducts are used on multiple occasions as a way for Frank Drum, among others, to eavesdrop on conversations his father, Nathan, has with others in the New Bremen community. This ability to listen without being seen is a common one for Frank throughout the novel; we see it happen in this context and we see it happen many times in the Drum house, where Frank listens to his father speak on the phone to someone or have a conversation with his wife and/or others in the downstairs of their home. The air duct, for Frank, ties in to his coming-of-age; two of the conversations he hears via the duct deal with sexuality; there is, first, the relationship counseling the Sweeneys receive from Nathan, and, secondly, there is Karl Brandt’s admission that he is gay. If the age-old adage is that children should be seen and not heard, here, we have Frank, who has entered adolescence, hearing adult conversations without being seen. 

A sizable number of important events happen on or near the trestle that passes over the river: Bobby Cole’s death; Frank’s sighting of Redstone with the corpse of the Skipper; Frank finding Redstone hiding on the trestle, after he’s implicated in Ariel’s death; Ruth Drum’s late-night, existentially-driven walk; and Frank’s sighting of Ariel’s corpse all being among them.