Helix Pedestrian Bridge

Amgen Incorporated, one of the world's largest biotechnical firms, recently developed a new research center on Seattle's Elliot Bay waterfront. As part of the research center, a pedestrian bridge was built that connects the campus with a major transportation corridor. The owner's goal for the new pedestrian bridge was to create a signature gateway to Amgen's campus. The pedestrian bridge is a three-arch structure that depicts a three-dimensional helix form. The overall shape of the bridge reflects the helical DNA that connects all life and references the vital research underway at Amgen. The arches create the outline of the basic DNA helix shape, while the deck support and roof trusses complete the remaining components of the helix form. The abstract double-helix form provided many design and construction challenges. The slim profile, large enclosed areas and suspended deck meant wind and pedestrian vibration would be a critical design consideration. The unique shape made it difficult to apply the standard building or bridge design codes. The contractor was faced with erecting this twisting structure over active railroad tracks while meeting tight geometric specifications. The bridge stands today as a testimony to the owner's vision, teamwork, innovation in bridge design and creative construction techniques. The bridge combines both form and function to show how an ordinary pedestrian bridge can become an extraordinary statement while serving its intended function. The project has won broad community support in the few months that it has been open.