Logan International Airport, I-90/Route 1A Interchange

The elevated roadways are constructed of cast-in-place, post-tensioned concrete box girders and supported on individual concrete columns, concrete bents, and concrete abutments. The columns are supported on large diameter drilled shafts. SGH provided construction engineering services, including the following:

• Preparation of reinforcing bar shop drawings for box girders and straddle bents for direct use in fabrication, reducing delivery time by several weeks
• Preparation of integrated drawings of box girders and straddle bents showing post-tensioning ducts, anchorages and reinforcement, block outs, reinforcing steel, anchor bolts, earthquake restrainers, drainage systems, and utility conduits to help resolve conflicts between embedded items in advance of construction
• Evaluation of concrete quality in a major drilled shaft using extracted deep core samples
• Evaluation of out-of-tolerance drilled shaft reinforcement to show that the drilled shaft was able to carry design loads safely
• Evaluation and repair design for missing post-tensioning bars in one of the straddle bents