Cut out the two sides of the bridge and the bottom of the span (which shows the girders underneath).
Fold the flaps on one bridge side and glue the bottom span inside the flaps carefully. Then add the second bridge side.
Cut out the support piers. It is easier to cut out the center holes first before cutting the support pier from the postcard. Glue two sides of each pier together. Color the white edges of the paper with a red pencil if you like (see Tips).
Cut out the stone bases of the support piers and glue them around the bottom of each pier.
Cut out the roadway (showing the bridge traffic). Place it between the sides and glue it on top of the span assembled in the first step.
Finally, add the piers at each end of the bridge. The center of the roadway should slightly overlap the hole in each support pier, but may require you to trim the end of the roadway or enlarge the hole in the pier slightly to fit.