My son is obsessed with anything with wheels. Thomas, Lightning McQueen, the backhoe from "I'm Dirty" and the garbage truck in "I Stink" (books by Kate and Jim McMullen), and any other thing that rolls, honks, or beeps. He even goes to bed each night with a garbage truck named Garbee. When he wakes up he carries it around all day wrapped in a baby blanket. He even feeds Garbee with a baby bottle.
I decided to feed off this obsession and take my kids to an overpass. Not far from us there is a big giant overpass over the freeway that connects the light rail station one one side to a parking lot on the other. Not only did we get to watch cars, trucks, buses, and even the occasional boat on a trailer, but we also go to watch the light rail trains come and go. I kind of expected this outing to last maybe twenty minute or so (I mean, how long can you watch cars go by really) but we ended up staying about an hour. I'm glad a brought a snack along!