90' Single-Track Railroad Through Girder BridgeWalthers Part # 933 4503, p. 171 Walthers 2021 HO Scale Reference. The Walthers Cornerstone 90' Single Track Railroad Through Girder Bridge kit is based on one of the most common North American railroad bridge designs. It's part of the Cornerstone Engineered Bridge System and is designed to be compatible with system abutments and bridge piers. Plate girder bridges are typically used to cross short distances between 30 and 90' 9. 1 to 30. 4m. Used for