Allnorth retained Pedelta to provide engineering services for the erection of the deck and installation of the hangers of the new Walterdale Bridge over the Saskatchewan River in Edmonton, Alberta.
The bridge has a 230 m deck and a single span with two 206 m thrust-arches, 54 m tall. The arches rest on massive thrust blocks supported by micro piles. The traffic deck has three lanes of northbound traffic with a separate shared-use path (SUP) on the east side and a walkway on the west side. The traffic deck is 22.4 m wide and accommodates three lanes, two lateral shoulders, barriers, and a sidewalk. The SUP deck consists of a tube box steel of variable width. This traffic deck is suspended by two planes of 16 hangers, each spaced at 10 m at centers and the SUP girder by one plane of 16 hangers.
Pedelta was assigned to develop complete erection procedures, including drawings and structural calculations, for the traffic and pedestrian decks and hanger installation. The project included two distinct options: preassembly of 88 m of the mid-span and lifting it into the final position, and stick build of the mid-span in cantilever.
Two distinct options for the deck steel members’ installation procedure were analyzed and fully engineered. The first option consisted of a stick build for the mid-span deck. Pedelta also developed an alternative method for the installation of the mid-span using a long deck segment using barges.
The analysis of the structure was conducted with a three-dimensional model with RMBridge v8i Software from Bentley Systems that incorporates all the structural elements in their exact three-dimensional position and the definition of all construction stages. The main project challenge was to meet the very tight project tolerances: Target final geometry (elevation + 25 mm/-0mm) for the arch, main deck, and SUP. The specified tolerance for the hanger forces was also very tight, at 5%.