Pipeline 101
Bridges

The Trans Alaska Pipeline System traverses 800 miles of rugged country, including 34 major rivers and almost 500 smaller creeks and streams. Thirteen of the crossings require elevated bridges. Nine of these crossings use plate girder bridges that are built from steel plates welded together into a trough that holds the pipeline. There are two suspension bridges, including this 650-foot bridge over the Tazlina River. There is also one tied arch bridge, consisting of a steel arch that has its legs tied together with a horizontal steel member, like a sideways “D,” and one orthotropic box girder bridge, constructed from steel plates welded into a box beam that underlies the pipeline.