Bridge-Supported Aerial Pipeline Installations—A Primer

Occasionally pipeline designers encounter situations where a bridge-supported aerial pipeline installation is necessary. This may occur at crossings of rivers, canals, ravines, highways, railroad tracks, or other obstacles where routing under or around the obstacle is unfeasible or impractical. These crossings present unique challenges not encountered in a buried installation, including pipe acting as a beam, pipe support, bracing and anchorage, movements induced by thermal effects, Poisson effects and the supporting structure, thrust restraint and transition back to buried conditions, among others. Factors affecting the aerial pipeline design include whether the pipe is pressurized or not, pipe material, joint types, and vertical and lateral support options. Installations must also consider constructability and maintenance access. This paper will provide an overview of common bridge-supported pipeline types, discuss the issues designers must consider, compare and contrast different installation types, and present some lessons learned from recent installations.