The flow of commerce beneath the cliffs of the Dayton's Bluff neighborhood on the southeast side of Saint Paul is nearly constant, whether it's by river, road, or rail. It's certainly one of the busiest train watching spots in the Twin Cities. That proved true again on this nice spring morning as I saw 6 trains in a little more than an hour. Here, three of the five tracks are occupied as a single Tier 4 GEVO leads a BNSF unit train of dried distillers grain eastbound.