In 2015, the Michigan Department of Transportation (MDOT) launched their I-75 Modernization Project, which will consist of eight construction segments. This I-75 widening and reconstruction project has been in the planning and development stages for 20 years. It encompasses 18 miles of freeway from M-102 to south of M-59.

Phase 1

SME provided geotechnical engineering services for Segment 1. These services were needed for new or widened roadway embankments; foundations for new bridges at the interchange and at Squirrel, Adams and Square Lake Roads; some temporary retaining walls; new culverts; new truss and cantilever overhead freeway signs; and new traffic signals at the Adams Road exit. SME also provided design assistance during construction.

Based on a review of soil survey data for the project site, there were two probable I-75 peat marsh crossings that were of concern. Additionally, I-75 passes over two glacial moraines, and there were glacial spillway features with possible organic soils between these two moraines. Peat marsh areas can be challenging for maintaining traffic staging operations and embankment widening designs. SME was selected by the project team for its extensive experience managing peat marsh issues for highway projects.

As part of our evaluation, we addressed foundation support for seven bridges and subgrade support for pavements, which included evaluating both shallow and deep foundation systems for the bridges. In addition, SME evaluated embankment stability (especially for bridge approaches), including possible part-width construction areas and embankment settlement estimates. For pavements, we looked for poor subgrade support areas and provided recommendations to address these areas. Further, SME evaluated key constructability issues that included addressing the likelihood of shallow groundwater; possible vibration or shakedown settlement concerns due to loose sands; and geotechnical issues related to maintaining traffic during construction.

Phase 2

 After successful completion of the  I-75 Modernization Project Phase 1, SME was pleased to be a member of MDOT’s design-build team for Segment 2.   SME was selected by the project team for our extensive geotechnical experience with roadway and bridge designs including ancillary structures; and SME’s geotechnical drilling and laboratory capabilities.
Segment 2 extends from north of Coolidge Road to north of 13 Mile Road – about 8.5 miles of interstate highway upgraded from 4 lanes to 6 lanes.  

SME provided geotechnical engineering services that were needed for the following: 9 bridges, 21 overhead signs, 19 tall (125’) light poles, 10 traffic signals for 3 intersections, 22 ITS/DMS, 3 large culverts, 7 storm water ponds, MSE abutment walls, and 4 miles of noise walls.  As part of our evaluation, we addressed foundation support for the bridges, which included evaluating both shallow and deep foundation systems.  As part of the geotechnical evaluation, we reviewed over XXX soil borings that were provided by MDOT to the design-build team.  Additional borings (with traffic control) were required for 3 of the bridge sites and for most of the ancillary structures.  The noise walls required numerous design iterations due to utility interferences and varying heights.

The design-build team was required to maintain two lanes of traffic in each direction during construction.  The northbound traffic was diverted to the southbound side during 2019, which required traffic to use both the inside and outside shoulders.  SME used our falling weight deflectomer (FWD) to locate areas of the shoulder requiring repairs and improvements prior to moving traffic onto the shoulders.  In total, only about 15 percent of the shoulder pavement required improvements.

During construction, SME provided geotechnical evaluation of subgrade support for foundations and MSE walls/embankments.  We also provided condition surveys of nearby structures, and monitored vibration levels coming from construction activities toward these structures.  The vibration levels were monitored using remote techniques whereby vibration data was transmitted via cell phone/internet to our office for review.