Clemson University Reflection Pond Master Plan and Design Improvements

Ardurra delivered a new 540-foot prestressed concrete girder structure replacing two aging bridges, one dating to 1948, along a key corridor north of downtown Seattle. Spanning Lake Union's Waterway No. 8, the bridge carries nearly 9,000 vehicles, more than 185 daily bus trips, and heavy year-round bicycle and pedestrian activity. During the Type, Size, and Location phase, the team evaluated multiple bridge and non-motorized alternatives to improve safety, enhance multimodal mobility, and strengthen connections to the Cheshiahud Lake Union Loop trail system. A multidisciplinary team assessed seismic and vibration demands, geotechnical constraints, and sensitive environmental requirements to identify the most resilient and cost-effective solution. Analysis and final design addressed construction duration, pedestrian and bicycle mobility, temporary transit detours, constructability, business and neighborhood impacts, potential trolley extensions, reconstruction of the adjacent floating walkway, and upgraded illumination. Additional work included environmental mitigation, fish habitat improvements, traffic control planning, and utility and stormwater treatment/conveyance design.

Key Highlights:

• Replaced aging structures with a seismic-resilient 540-foot prestressed concrete girder bridge, improving safety and reliability for 9,000 daily vehicles, 185 bus trips, and heavy bicycle and pedestrian traffic
• Reconnected waterfront experience by integrating the regional trail network and rebuilding the floating walkway to enhance year-round access and recreation
• Engineered fish habitat and shading mitigation, high-voltage utility relocations, and carefully staged transit/traffic detours to maintain corridor function during construction

The project strengthened a vital mobility link for Seattle while reconnecting the waterfront trail network and delivering complex environmental mitigation and utility coordination that minimized disruption to transit, vehicles, cyclists, and pedestrians.