Orthotropic Steel Deck Bridges Jigsaw Puzzle Orthotropic Steel Deck Bridges Want to see orthotropic steel deck (OSD) bridges become more commonplace? So do we! The Federal Highway Administration’s new Guide for Orthotropic Steel Deck Level 1 Design suggests details for closed- and open-rib OSD systems, reducing fabrication costs and simplifying the design process for a 100-year-plus deck solution through the AASHTO Level 1 approach. Assemble this view of the Poplar Street Bridge over the Mississippi River in St. Louis! Then learn more about OSD applications in the U.S in this month’s Modern Steel Construction Steelwise column at aisc.org/osd-bridges.