New Pitt River Stay Cable Bridge in Canada Solves Long Term Traffic Congestion Problem
The Pitt River Bridge and its approach roads are part of the Province of British Columbia’s Gateway Project, which will dramatically improve the region’s traffic flow. The new stay cable bridge over the Pitt River provides up to 16 meters of vertical marine clearance and connects Pitt Meadows and Port Coquitlam in the suburbs of Vancouver.
The 198 Million Canadian Dollars project was jointly funded by the BC Provincial Government and the Canadian Federal Government and built by the general contractor Peter Kiewit Sons Inc. Construction occurred between late 2007 and October 2009. The bridge has a main span of 190m, a width of 40m, and contains three planes of stay cables in two pylons.
DSI Canada Ltd. was awarded a contract to supply the DYNA Grip® Stay Cable System, stressing equipment and technical assistance. Several DSI units were involved in this important infrastructure project: DSI Canada was supported both by DSI USA and by DSI HQ Operations.
DSI supplied a total of 96 stay cables consisting of 64 Type DG-P31 Stay Cables and 32 Type DG-P61 Stay Cables. A total of 306t of Type 0.6" 7 wire galvanized, waxed and HDPE sheathed low relaxation Gr 1860 MPa Strand was supplied. Each stay cable was encased in an HDPE outer sheathing with helical spirals on the outside to mitigate rain-wind vibrations. External viscous dampers were installed on the 24 cables that are longer than 80 meters. Damping for the other 72 cables was provided by elastomeric disks attached to the cables.
Stressing of the stay cables was performed using the DSI Con-Ten Single Strand Stressing System and was carried out in two phases. The first phase was executed after the erection of the steel girders, and the later one occurred after installation of the composite concrete deck. DSI performed calculations to determine the individual strand forces, considering the displacements of the cable anchor points during stressing. The anchorages include a ring nut which allows for a future adjustment of the loads in the stays. Thanks to the DYNA Grip® Stay Cable System, the force of individual strands can be verified and individual strands can be replaced at any time in the future.
Since October 2009, traffic flows freely over the new bridge. Demolition of the two existing swing bridges, which were replaced by the new bridge, took place in summer 2010.