A recent Civil + Structural Engineer article authored by Simpson Gumpertz & Heger (SGH) building technology staff members discusses how the design and construction of pavement and waterproofing systems on bridge decks differ from roadways on grade. In “Membrane-Level Drainage on Highway Bridge Decks,” Senior Project Manager Philip Moser and Senior Principal Gregory Doelp describe the unique waterproofing challenges posed on bridges and explore the lack of consensus on how best to design these systems.
Waterproofing systems on bridge decks – often a series of small-diameter PVC pipes – may seem haphazard in appearance but are critical in practice to provide a drainage outlet and improve pavement durability. However, the authors write that “Despite the consistent recommendations for membrane-level drainage on bridge decks in industry literature, and the availability of example details, the approaches taken to bridge deck drainage – and to bridge deck waterproofing in general – seem to vary around the country and around the world.”
In the article, the authors note that there is an opportunity for improved knowledge sharing and consistency regarding bridge deck drainage across the industry. The article points out several obstacles that that prevent proper design, including constraints on outlet locations, the prevalence of existing bridges without drainage systems, organizational challenges to recognizing best practices, and lateral drainage concerns.
“On most bridges, these challenges can be overcome, and at least some membrane-level drainage can be provided to improve the durability of the pavement,” the authors conclude. “The benefits of improved pavement durability, waterproofing longevity, and traffic safety are worth the effort of installing membrane-level drains.”