William R. Bennett bridge – Ten years of performance monitoring

ABSTRACT: The five-lane William R. Bennett Bridge across the Okanagan Lake in British Columbia was constructed and opened to traffic in July 2008. The bridge has an elevated-fixed-structure on pile foundations over shallow water and a floating structure on pontoons over deep water. Subsurface soils along the bridge alignment include very soft to soft compressible silts and clays and loose to compact sands. The bridge approach embankments were constructed following preload treatment. Settlement of the approach embankments was estimated using laboratory test data on soils, then updated using analysis of the preload settlement data. Settlement of pile foundations was estimated using consolidation parameters derived from laboratory tests. Post-construction settlement survey was conducted to assess the performance using shallow and deep settlement gauges installed on and within the approach embankments, on the bridge piers and on the abutments. Baseline survey for settlement monitoring was carried out immediately after construction in June 2008 and then annually from June 2011 to June 2018. The survey monitoring data shows satisfactory performance and the measured settlement magnitudes are within the prediction. This paper presents a brief description of the design and construction of the bridge, geotechnical analyses, preload data, settlement prediction and the measured post-construction data.