Building cofferdams is the first step in building the new northbound bridge

From ODOT -
With the temporary bridge removed, construction on the new northbound Willamette River Bridge drilled shafts will begin early in the new year. We plan to open this bridge to traffic by fall 2013. Before then, a lot of work needs to be done.
A critical first step is constructing cofferdams. These temporary enclosures keep water and soil out of the work area while we build new bridge footings and shafts in the river and on each bank.
To build our cofferdams, crews drive sheet piles deep down to the bedrock to establish a enclosure. They then excavate soil from inside the enclosure. Water may be needed to be pumped out to create a dry and safe work space.
When the cofferdams are finished, we will use large drilling equipment to bore holes deep in the ground so workers can install steel reinforcement and pour concrete shafts to provide support for the bridge columns.
We’ll have more photos and details on building the new bridge as construction work continues.
This photo shows one of the cofferdams from the southbound bridge.