I17 Widening: Phoenix to Black Canyon City

The Arizona Department of Transportation (ADOT) is widening the existing Interstate 17 (I17) between Downtown Phoenix and Black Canyon City. The first phase of the project called for widening of I17 between SR 101L and Carefree Highway. ADOT retained Parsons Brinkerhoff (PB) to prepare the design for the 30% stage. NCSG performed the geotechnical investigations under subcontract to PB.

The reconstruction of mainline I17 needed to address 13 bridge structures and pavement design. Some existing bridges involved wideneding on the inside while others needed to replaced completely. Additionally, several new traffic interchanges (TI) were proposed for construction including bridge structures and possibly retaining walls. The field investigation program conducted by NCSG 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.

Most of this project has been completed.