The Arizona Department of Transportation (ADOT) is proposing to widen the existing Interstate 17 (I-17) as part of the Management Consultant Contract between Downtown Phoenix and Black Canyon City. The first phase of the project calls for widening of I-17 between SR 101L and Carefree Highway. ADOT retained Parsons Brinkerhoff (PB) to prepare the design for the 30% stage. NCS performed the geotechnical investigations under subcontract to PB.

The reconstruction of mainline I-17 will include 13 bridge structures and pavement design. Some existing bridges are being widened on the inside, others are being replaced completely. Additionally, several new traffic interchanges (TI) are proposed for construction including bridge structures and possibly retaining walls. The field investigation program conducted by NCS included 50 borings for the various bridge structures and the pavement analysis. Due to the hard soils at the site, the tubex system (air rotary) was used for drilling the deep structural borings while conventional hollow stem augers were used for the pavement borings.

Portions of this project are currently under construction.