As a result, in the middle of design development, MKA moved into construction documents. "We had to consider the structure set and let MKA go, or we would not be able to coordinate the mill orders," says Diesko. HNTB "froze" the structure, as if it were an existing building, much earlier than is typical, adds Lanson Nichols, HNTB's vice president.
The strategy worked. "We got our first design development package to buy structural steel and vertical transportation in November 2011," says Harvey.
After design development, the new schedule eliminated a two-month "pencils down" period for the design team so the joint venture could create the GMP. It is also slicing two months off the original 28-month construction schedule.
TDJV's contract calls for substantial completion in August 2014. That cuts out a typical three-month buffer between substantial completion and the first game.
About a year ago, the team had a meeting with the city to develop a multiple drawing-package review strategy for phased permitting of the steel structure, the foundations and the concrete. To expedite the steel permit, MKA proposed combining a peer review of the structure, which the 49ers wanted, with plan checking. For this, the city agreed to deputize structural reviewer John A. Martin Associates (JAMA), Los Angeles, as part of the building department.
"We also did a courtesy review," says Sheila Lee, building official for the Santa Clara Planning & Inspection Dept. "This is a very challenging project for my department because of the size and tight time line. We don't compromise anything."
MKA split the structure into eight plan-check packages, submitting them in stages from Nov. 4 to Feb. 17. While JAMA reviewed one package, MKA continued to engineer others. This strategy saved a minimum of two months over a more traditional two-step foundation-and-superstructure review process, says Brian A. Dickson, an MKA principal.
To speed work, TDJV's Masel split the building into four quadrants and constructed them concurrently instead of using more traditional, "racetrack" oval sequencing. Crews used four drill rigs for the auger cast piles, for example. Workers are erecting steel with four crawler cranes, one for each quadrant.
TDJV is using building information modeling for interference checking. To date, there are 402 requests for information, instead of three or four times that amount, thanks to IBDB with BIM, says Harvey.
BIM also was used to locate and build the deep utilities below the slab on grade so they could be built ahead of piles instead of after them. Crews worked 24-hour shifts from May 1 to May 15. That move cut the time in half for the deep utilities work, says Harvey.
Out of Sequence
TDJV had field-level electrical rooms, made of cementitious masonry units, built out of sequence. That move allowed the electrical switch gear, transformers and panels to arrive early so the electricians can streamline the electrical rough-in and distribution. These rooms would fall under normal field-level CMU and drywall construction, after fireproofing, and potentially cause delays in construction, says Harvey.
Crews have been installing sleeves, block-outs and inserts in the metal decks on swing shifts. The same is true for slab-on-metal-deck pours. This tactic allows for continuous steel erection during the day.
On June 1, more than one month after construction started, HNTB and MKA were officially assigned to TDJV. Because of the acceleration, WSP Flack + Kurtz, the bridging mechanical-electrical-plumbing engineer, did not get transferred to the design-build team. To expedite the work, the team made a decision to bring in a design-build mechanical contractor.
Work started on April 23 and is speeding along. Steel erection began on July 30 and is 77% complete. Topping out is expected in December. On Sept. 4, tower cranes started lifting in escalators. "To see escalators actually set at this stage is phenomenal," says HNTB's Diesko.
On Oct. 26, crews installed the first piece of structural precast concrete for the seating treads and risers. The project is on course for substantial completion one month ahead of even the accelerated schedule, says Harvey.
The IBDB and acceleration strategies have worked out so far, says the 49ers' MacNeil. "We are pleased with the design-build team," he adds. But with only 22% of the project complete, the race is far from over. "We haven't deployed the parachute yet," says MKA's Magnusson.
