Bridge construction, steel construction: One of each pier in the last/west two sets. Top of near pier has two sets of rollers for the bottom chord of the Mabey Bridge to be pushed onto and to be supported as the bridge frame is pushed to the far pier. Each roller has a perpendicular bolt that is tightened against the roller to lock it when the frame is not being pushed. The bolt for the left near roller is prominently shown in the center of the inset detail. Appearing beyond the rollers is timber cribbing that forms the top of the last pier on the left side, which will support the bridge frame at the end of its erection and push from the east bank. Tyngsborough, Massachusetts 2005.

Bridge construction, steel construction: One of each pier in the last/west two sets. Top of near pier has two sets of rollers for the bottom chord of the Mabey Bridge to be pushed onto and to be supported as the bridge frame is pushed to the far pier. Each roller has a perpendicular bolt that is tightened against the roller to lock it when the frame is not being pushed. The bolt for the left near roller is prominently shown in the center of the inset detail. Appearing beyond the rollers is timber cribbing that forms the top of the last pier on the left side, which will support the bridge frame at the end of its erection and push from the east bank. Tyngsborough, Massachusetts 2005.