Air Traffic Control Tower (Hanscom Field)

GEI Consultants provided geotechnical engineering support for the design and construction of a new Control Tower at Hanscom Field, in Bedford, Massachusetts. The Federal Aviation Administration (FAA), and HNTB, Inc. of Boston, Massachusetts, were building the new Air Traffic Control Tower and Base Building to replace an outdated, existing control tower.

For this project, our expertise was needed for the design and construction of the tower foundation.

We first performed a subsurface exploration program consisting of borings and geotechnical laboratory testing. Based on the subsurface conditions we encountered with this program, we then developed recommendations for engineering soil properties.

We also evaluated the presence of environmental contamination in the soils within the building footprint. Our evaluation was to characterize the on-site soils, and to assist the owner in evaluating disposal options for the soils excavated during foundation construction. We also performed the engineering analyses needed to select the appropriate foundation type.

In our soil analysis, we discovered the presence of a thick compressible silt stratum at the site; a deep foundation would be needed to support the tower.

The tower is tall, with a relatively small base area. Four drilled shafts support the tower, one at each corner. The drilled shafts were designed to resist large vertical loads, both in uplift and in compression. They also needed to resist the overturning forces on the tower design’s earthquake and wind loads. To resist the large loads, we secured the drilled shafts with sockets into a suitable bearing stratum below the silt.

We also provided construction oversight and monitoring. This included contractor submittal review and the monitoring of the construction of the drilled shafts, involving inspections of the bearing surface at the bottom of each shaft.

Construction of the new tower is completed, as shown in the photograph, and the old tower is scheduled for demolition.