I've run through the Ironworks twice now and have gotten to the fence where the four symbols are posted, but I don't know what to adjust to match them (e.g., there are no chimneys there). I've run along that platform one end to the other and no X-interaction boxes open. Any hints or downright help would be appreciated. I can see Street Sweepers behind the fence and it's really frustrating that I don't know how to get to them!
