Work is progressing steadily higher on the new 17-story Multnomah County Central Courthouse near the Willamette River in downtown Portland.

Construction kicked off in October 2016, and in early 2018 crews moved beyond the building's first three floors. The on-site construction crane is expected to reach 75 ft to build the top stories, as work moves toward the 2020 opening of a new courthouse replacing the historic building currently in use.

The $324-million project is led by construction manager/general contractor Hoffman Construction, which is using post-tensioning cables inside the concrete floors of the building to allow for thinner floors than typically seen. Conduits for electrical systems will be installed in the concrete and documented with a scan to simplify operations and maintenance of the structure for the future, the firm says. Building systems for the courthouse were tested in mock-ups and will then be retested as the building gets constructed.

J.D. Deschamps, project manager, gave an example of the sequence, with a building section constructed offsite being subjected, thanks to the use of an airplane engine, to wind loads of 120 miles per hour and rain loads of 4 inches an hour, far more than anything ever expected in Portland. The mock-up passed the test, yet another wind and rain test will take place on the actual building as the outside façade takes shape.

Hoffman expects to continue building about one floor every 16 days and the façade will start to form once the 12th floor is completed.

As the new courthouse remains on time and on budget, the county has put the existing central courthouse up for sale. It was built between 1909 and 1914 when the county had one-third of its current population and long before modern building code standards. Listed on the National Register of Historic Places, the county expects the building to be renovated by a new owner.

The new courthouse moves closer to the river at the west end of the Hawthorne Bridge at SW First Avenue and SW Madison Street. Designed by a team led by SRG Partnership, the new courthouse will include solar panels on the tower roof, 45-ft-tall columns in the entry (the wooden forms for the columns were meant to transfer the grain to the concrete, providing a differentiating texture), green roofs on Jefferson Station and the lower section of the courthouse and views of the Willamette River, all while targeting LEED Gold during construction.

Follow Tim Newcomb on Twitter at @tdnewcomb.