The panel will review repairs and make recommendations for current and future pontoon cycles.
Work has been under way to address cracking discovered last month. WSDOT said that repairs have been successfully implemented on four pontoons under construction in Aberdeen in the western USA.
However, cracks developed in new areas of one pontoon last week following post-tensioning. To help analsze the cause of this new cracking, repair options and the repairs made to date, WSDOT has convened a peer review panel this week.
Repairs carried out so far have included removing concrete, adding reinforcing steel and pouring new concrete on sections where the concrete had cracked and flaked after post-tensioning.
“These pontoons must be safe and functional for 75 or more years,” said state transportation secretary Paula Hammond. “On any big project like this, there are issues that arise and refinements that are made. We welcome the expertise of our panel as we address the things we’ve encountered and look forward to successfully building the new SR 520 floating bridge.”
Hammond said the panel will review the design and construction of the pontoons and the repairs made to date. It will also consider additional repairs that may be necessary and possible design or construction changes for future pontoon cycles. While some cracking in concrete is expected, Hammond said WSDOT will ensure the cracks are repaired, as well as minimised in future cycles.
The review panel began its work Monday, with interim findings expected during the week of 9 July. Panel participants have backgrounds in structural analysis, prestressed concrete and steel design, risk assessment and long-span bridges under seismic conditions. Individual panel members have worked on projects internationally, in the United States and in Washington state, including the Interstate 90 and Hood Canal floating bridges and the Tacoma Narrows Bridge.
The panel members are Dr Neil Hawkins, professor emeritus at the University of Illinois and former chair of the civil engineering department, University of Washington; Tom Sherman of TES Enterprises, specialist in floating bridge design and construction; and Dr John Clark, a consultant in long-span bridges and heavy structures. The panel is chaired by John Reilly, who has experience in management, risk assessment and pre-stressed concrete.
“WSDOT and our contractor, Kiewit-General, are committed to high quality in these pontoons so that they will form the foundation for the world’s longest floating bridge and serve the public well for many decades to come,” said SR 520 program director Julie Meredith.
