GeoMetrix was retained as the prime consultant for the deck rehabilitation and finger joint replacement of BF 74227 on Highway 88 over the Peace River near Fort Vermilion, and the rehabilitation of BF 73694 on Highway 60 over the North Saskatchewan River near Devon. These major bridges required extensive deck rehabilitation, and replacement of the finger plate deck joints with modular deck joints. Other maintenance work included bearing rehabilitation, steel girder strengthening, and substructure concrete repairs. GeoMetrix was also retained as the prime consultant for the design of the Lily Creek and Brady Creek Bridges on Highway 88 near Slave Lake
BF 74227 on Highway 88 over the Peace River:
For bearing repair and resetting, during value engineering GeoMetrix identified constructability and durability issues with the original bridge jacking procedures, that required the Contractor to design and install four steel jacking frames in the confined space of the two steel tub girders. GeoMetrix re-engineered the jacking procedures by utilizing the existing pier diaphragm, which greatly reduced the construction cost.
The existing finger joints had previously been repaired numerous times due to the broken fingers. The proposed new finger joints in the original design would not fit in the reduced gap between the deck and the abutment caused by creeping of the headslopes. GeoMetrix redesigned the joint replacement with modular deck joints which were able to accommodate the narrowed gaps and movements of the bridge.
BF 73694 N/S on Highway 60 over North Saskatchewan River:
The finger joints of the twin 360 m long steel plate girder bridges had experienced numerous broken fingers and required frequent maintenance. After a thorough bridge inspection and careful study of the record drawings GeoMetrix identified that the rocker bearings could only accommodate horizontal movement with the finger joints installed along the 2.5% vertical grade. This incompatibility caused high fatigue stresses in the finger plates. To resolve the problem GeoMetrix studied three replacement options and recommended a modular joint replacement. Currently this type of joint is not pre-approved by Alberta Transportation, however, GeoMetrix demonstrated to the Technical Services Department at Alberta Transportation that a modular joint replacement is the most economical and reliable solution for long bridges with rocker bearings. Through this research, GeoMetrix was able to get this joint approved for use. Our findings and innovative design will provide the Department an alternative solution of this long-lasting finger joint fatigue problem.
Lily Creek and Brady Creek Bridges on Highway 88
Due to a 100-year return period flood the original structures were washed out and needed to be quickly replaced in order to restore traffic flow. The project included detour construction, NU-girder fabrication, debris removal, headslope gravel wedge construction, stream restoration, bridge construction, detour decommissioning and site clean-up. The design and construction work was completed from Summer 2019 to Fall 2020.
