70' Single-Track Railroad Through Girder Bridge -- Kit - 9-3/4 x 2-3/8 x 1-5/16" 24.7 x 6 x 3.3cm. The Walthers Cornerstone 70' Single-Track Railroad Through Girder Bridge kit is based on one of the most common North American railroad bridge designs. - Model Trains, HO Scale, HO Scale Layout Items