Atlas 880 HO Code 100 Through Plate Girder Bridge - Single Track - KitAtlas 880 HO Code 100 Through Plate Girder Bridge Single Track Kit The through plate girder bridge is based on the prototype that sported construction of a bridge deck supported between two plate girders. This type of construction gives it the easily identifiable 'U' shape. The construction depth on this type of bridge was much less than on other bridges providing a minimal change of height while clearing terrain. It was a common sight on railroads.