Operational improvements to an approximate 27 km stretch of Highway 15 between Seeley’s Bay and Crosby Creek in Eastern Ontario included a new bridge. As part of those improvements, the existing 12 m long single span bridge over Crosby Creek, founded on timber piles, had reached its usable life span and was replaced with a new bridge.
The new realigned bridge, located approximately 16 m east of the existing bridge to address geometric design standards, is a 22.5 m span prestressed concrete box girder integral abutment bridge founded on steel H-piles socketed into the bedrock. Approach embankments on the north and south side of Crosby Creek have a maximum height of 4 m.
The approach embankments are founded on a 2.7 m to 3.9 m thick deposit of clayey silt to clay underlain by a silty sand to sandy silt till which in turn is underlain by gneiss and granite bedrock. Lying beneath a stiff to very stiff desiccated crust of thickness ranging from 1 to 1.8 metres in thickness, the soft clayey silt to clay stratum provided design challenges related to the settlement and stability of the embankment.
Following a comprehensive review of embankment foundation design alternatives, ground improvement utilizing aggregate piers was chosen as the preferred option. This paper presents the results of the foundation investigation program, the design methodology, the contract package development including performance specifications, contract delivery method, and embankment construction and monitoring of the embankment during and following construction.
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