Setting the 2+U Columns in Seattle
- Two 75T TL150BW Trilifters
- K25 Kamag 10 line SPMT
- 550T Grove GMK7550 crane with 352,700 lbs of counterweight and main boom with Mega Wing
- 485T Liebherr LTM1400-7.1 crane with 308,600 lbs of counterweight and main boom
Skanska approached our Seattle office to help out with one of the premier construction projects in the Emerald City. Our job was to both transport and set twenty columns for the construction of the 2+U building in downtown Seattle, Washington. With the site being downtown and near frequented landmarks, space and accessibility were extremely limited. Strategic planning along with the right tools were needed to get the job done. For our Crane Services and Specialized Transportation and Rigging teams, this was an opportunity to shine.
Limited Space and Noise Restrictions
The task of transporting and setting 20 precast tapered concrete columns–each weighing between 69,000 and 165,000 lbs–was a complex job. But it was a job we could certainly handle. During many months in planning, we worked through both technical and logistical details to ensure a smooth operation.
2+U is located between busy downtown streets with steep hills, underground vaults, trees, powerlines, and trolley wires. This crowded space added a lot of complexity to crane placement and column transportation. However, the crowded space wasn’t the only hurdle to overcome. The area surrounding 2+U is also known for heavy traffic as a result of notable landmarks and nearby housing. Consequently, our crew also had to plan for night-time noise restrictions and road closure restrictions which led to 39 permit applications and authorizations.
Innovative Solutions and Preparation
On the technical side, years of experience and skill came in handy as our engineering team worked to develop a comprehensive solution for working in the seemingly impossible location. The solution involved an SPMT, trilifters, two cranes, and a custom rigging solution involving a swivel trunnion and a passing triangle.
With columns of this size and weight in an area with no safe margin for error, we knew cross checking our plans was not merely optional, but essential. Before performing the job onsite, we built a scaled model of our rigging setup. When that turned out as expected, we performed a full-size test lift offsite. The runthrough went off perfectly, and we were ready for the job.
Equipped with a solid plan of action for safety and efficiency, we began the project with both confidence and caution. Before each phase, we performed a job hazard analysis, and before each lift we held pre-task plan and pre-lift meetings. We brought in the columns one by one on over-the-road trucks. Once onsite, we transloaded each of the columns to a 10 line SPMT using two trilifters. The SPMT transported the columns into the skyscraper, where they were positioned under the crane hooks. Once under the crane hooks, we used two cranes to share the load for the uprighting process. Our two crane solution was made possible in the tight space by our custom rigging setup. Over the course of two weeks, the execution of the plan went off without a hitch and the 20 columns were set in place.
The Skyscraper is the Limit
Yet again our guys made #doingtheimpossibledaily happen, through 358 engineering hours and over 1600 crew hours. In the face of logistical and technical complexity, we were able to complete the project on time and with zero injuries, incidents or lost time on the job.
Once the entire construction project reaches completion, 2+U will stand 80 feet tall and hold 38 stories, resting on the 20 concrete columns set by our crane team. Completing our portion of the project was a satisfying achievement for our team. At Omega Morgan it doesn’t matter how difficult the job may be, the sky is the limit… or, in this case, the skyscraper.
To learn more, watch our video about the project here: https://www.youtube.com/watch?v=Le43KHxaCQI