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Constructing a 30-story building on a small half block in downtown Portland isn’t easy.

That’s why Hoffman Construction Co. and its Park Avenue West project partners are performing much of the prefabrication work off-site. Coordination, technology and a lot of patience are going into work to finish each level of the building’s spine with cement pours.

“We’re trying to orchestrate a careful plan,” project manager Eric H.I. Hoffman said. “It’s unimaginable how many people have to touch that plan in a coordination effort. We’re getting down to the smallest piece.”

After several years of delays, Park Avenue West construction resumed in November. Excavation is completed, and crews are now building a six-level parking garage that will be one of the deepest in Portland when it’s completed in April, Hoffman said. Simultaneously, a new level of the building’s concrete core is being created about every six days.

With about 80 workers currently on the site, space is packed. Light rail trains pass along both the north and south ends of the property, leaving only Park Avenue and Ninth Street available for deliveries by truck. With little room for storage, materials are quickly hoisted by crane into place.

“I can’t think of any part of it that’s not a challenge that we’re constantly managing,” Hoffman said. “This tiny footprint will be transformed into this massive outcome. There are so many parts and pieces. It’s unimaginable the amount of content that comes into a building.”

For the concrete core, Hoffman is using a “jump-form system” – a self-erecting forming system that uses hydraulic jacks rather than a crane.

Each day of the six-day cycle is heavily coordinated. On day one, the core wooden forms are broken loose and raised to the next level by the jacks. Rebar is prefabricated off-site and then installed inside the wooden forms over several days.

“That’s a tough operation, a nasty operation,” Hoffman said. “There are all kinds of parts and pieces to install.”

On the sixth day, a pump pours concrete into the form. After the concrete hardens, the form comes loose, and the cycle repeats.

Completion of the concrete spine will provide seismic and wind resistance for the whole building, said Anne Monnier, principal at KPFF Consulting Engineers, the project’s engineer. The core will house stairwells and elevators, along with mechanical and electrical systems.

“It also allows the contractor to pour the concrete and get those trades working and pouring before we get the steel guys in and swinging floor beams, columns and support floors,” Monnier said.

Prefabrication work is taking place in Tigard, where steel fabricator Fought & Co. is prepping the beams and columns for installation.

Steel assembly work will start in about a month and chase the concrete spine to the top, Monnier said.

“They will start bringing them out by the truckload – as much as they can install in a single shift,” she said.

KPFF started working on the project eight years ago, along with the project’s architect, TVA Architects, Monnier said. The steel was bought five or six years ago and has sat in storage, she said.

The original design was for a 34-story building; then, it shrunk to 26 stories before gaining final approval last year at 30 stories. As the design changed, so did the steel placement plans, Monnier said. The project team spent about three months redesigning steel cuts and where they would be placed, she said.

“These are not just straight sticks of steel,” Hoffman said. “They have complicated connection points. They are cut to the exact size.”

Building Information Modeling is playing a huge role in Park Avenue West project coordination. All the structural steel, concrete, and mechanical, electrical, plumbing, fire protection and other systems are modeled using 3-D technology that allows Hoffman’s subcontractors to perform much of the work in advance off-site, BIM manager Dale Stenning said.

“The benefits of doing this – we have far fewer needs to remedy problems in the field,” he said. “A larger percentage of labor can work off-site. This continues to improve quality and lower prices.”

The modeling allows Hoffman’s subcontractors to deliver exactly what will be used on a specific day without the need for storage on-site, Stenning said.

The final building will be similar to the 13-year-old Fox Tower nearby, though more technologically advanced, said Vanessa Sturgeon, president and CEO of Park Avenue West developer TMT Development. Both Hoffman and TMT are headquartered at Fox Tower.

One of the main differences will be Park Avenue West’s glass skin glazing.

“They’re going to look significantly different, but both will essentially be glass and metal buildings,” Sturgeon said. “The glass on Fox Tower is really dark in color, but on Park Avenue West it will be clear. It will still be able to keep out heat and cold just as well as the dark color glass.”

Construction of Park Avenue West is expected to cost $131 million and finish in December 2015. The building will hold 15 floors of high-end apartments, 13 floors of office space and two floors of retail space totaling more than 600,000 square feet.