DBA recently completed construction observation of pile driving and earthwork for TH-84 across Norway Brook in Pine River, MN. The structure may look like a run of the mill bridge, but the project was replete with geotechnical challenges associated with constructing a new bridge at the toe of an active dam. (We use “run of the mill” with all due affection; there’s no such thing as a boring bridge to DBA.)
During the design phase, DBA designed an instrumentation system and used the resulting piezometric information to calibrate seepage models for the site. The calibrated models were used to analyze conditions during and after construction of the new bridge. DBA also developed an emergency action plan (EAP) that established items to observe during construction, defined levels of distress leading up to all potential failure mechanisms, and designated response actions associated with the distress levels. During construction, DBA was on-site to implement the EAP, coordinating with the contractor, Schroeder Construction, Inc., and MnDOT to quickly respond to any evidence of distress.
Throughout analysis, EAP development, and EAP implementation, DBA collaborated with the bridge designer, Parsons, and MnDOT to identify, explain, and manage the risks associated with this unique and challenging project. We are pleased to see live traffic crossing the dam in the picturesque Minnesota North Country!
Here is a link to a video shot by Dan Ding of DBA during construction:
Finally, some photos of the finished bridge: