The senior engineering design projects at Calvin College tend to encourage ambitious thinking, and among this year's crop of senior projects is a concept that would take $4 million and 350 tons of steel to realize: It's an automated, retractable pedestrian bridge designed to span the St. Joseph River channel in St. Joseph, Michigan. The bridge, or at least a scale model of it, was produced by senior design team number 13, "The Pedestrians," whose members are Craig Baker, 21, a mechanical engineer from Strathroy, Ontario; leanne Bock, 22, a civil and mechanical engineer from Almont, Michigan; Melanie Haagsma, 22, a civil engineer from Grand Rapids; and Abby Stemler, 21, a civil engineer from Elk River, Minnesota.