In addition, the contractor helped the previous owner find a new buyer and interviewed 10 developers until the property was acquired in late 2012. Swinerton restarted and engaged all subcontractors to confirm a guaranteed maximum price, revise the schedule and restart construction.

With the adjacent Transbay Transit Center already underway when construction resumed, the team had to contend with constrained laydown and staging areas. “This required extensive coordination of construction activities and concise delivery scheduling for all building components,” says Terry McKellips, Swinerton’s vice president and division manager.

The company also had to coordinate with project subs to explain “vertical” sequencing—a strategy that calls for working on more than one floor at a time. “Since the majority of subcontractors maintain a ‘horizontal,’ or floor-by-floor intuition, we educated them on this more efficient vertical sequencing concept. This kept the project schedule on track for an on-time completion date,” McKellips says.

A temporary steel bridge over the Mission Street sidewalk electrical vaults became an unusual staging area.

An energy-efficient unitized curtain wall system has a radiant low-e coating and air gap. To reduce shadows on surrounding properties, the tower tapers at its corners. Other sustainable features—which helped the project become the first LEED Platinum Core & Shell-certified office building in the city—include a stormwater retention system, advanced mechanical systems, improved indoor air quality with air-economizer ventilation systems and extensive daylighting.

535 Mission Street

San Francisco

Key Players
Owner Boston Properties Inc.
Lead Design Firm HOK
Contractor Swinerton Builders