The I-69/I-475 interchange in Flint, Michigan, is a vital corridor serving major economic generators and providing direct access to the City. Over time, the deterioration of this critical artery began to hinder efficient traffic flow causing numerous safety concerns that posed significant risks to the community. Recognizing the urgency for upgrades, Michigan’s Governor allocated Rebuilding Michigan funding to expedite the project schedule by more than a year, committing swift action to address these pressing issues.

Addressing Critical Needs with Innovative Solutions

Colliers Engineering & Design, in collaboration with the Michigan Department of Transportation (MDOT), undertook the challenge of transforming the I-69/I-475 interchange. The project’s success hinged on addressing the unique challenges posed by the existing infrastructure while implementing creative and effective solutions. The Performance-Based Practical Design (PBPD) approach, approved by the Federal Highway Administration (FHWA), allowed the team to focus on eliminating non-critical project design elements linked to low or no crash histories. This strategic allocation of resources provided maximum value to the traveling public while adhering to budgetary constraints.

One of the most significant challenges was addressing the Flint Water Crisis. The project team was acutely aware of the crisis’s social and economic impacts. As part of the design, existing watermains crossing the right-of-way were replaced or upgraded at MDOT’s cost. This proactive measure not only ensured continued action to help remedy the crisis but also averted the need for future rework within the new corridor, demonstrating a commitment to sustainable development for the community.

Innovative Engineering Techniques

The Colliers Engineering & Design team used several unique techniques to overcome the project’s complexities. A notable example was the design of an innovative wall system to address global stability concerns and increase substandard bridge clearances along I-69 without replacing otherwise good-condition bridges. This wall system served as temporary earth retention and a new highway barrier for the lowering of I-69 while ensuring safety and stability.

Another significant challenge was the presence of the abandoned “What Cheer” coal mine under portions of the project area. To mitigate safety concerns during construction and long-term operation, the team, in collaboration with MDOT and Michigan Technological University, developed strategies to stabilize the area. This included constructing a reinforced cap and using flowable fill for voids, guaranteeing the ground’s integrity and safety.

Complex bridge deck demolitions and replacements were also a major part of the project. The use of ChromX reinforcement steel, a low-chromium stainless steel product, was used to ensure the long-term durability of the rehabilitated structures. This material choice addressed significant deterioration and enhanced the longevity of the bridges, providing a sustainable solution for future infrastructure resilience.

Community Impact and Long-term Benefits

The successful completion of the I-69/I-475 interchange project has had a profound impact on the community and the broader region. Infrastructure upgrades have significantly improved safety, reduced travel times, and provided smoother rides for motorists. The collaboration with the City of Flint also resulted in much-needed infrastructure investments, benefiting local residents and regional travelers alike.

The project has generated significant enthusiasm within the engineering and surveying profession, providing valuable experience for both senior and newer engineers. The techniques and solutions developed during this project can be applied to future projects, enhancing the overall quality and success of infrastructure developments throughout the state.

Testament to Collaboration and Ingenuity

The partnership between MDOT and Colliers Engineering & Design was instrumental in the success of this complex project. “On a very condensed schedule, Colliers Engineering & Design worked flawlessly with MDOT and stakeholders to develop a project that met the needs of the community and tackled numerous safety and geometric issues,” shared Jeremy Hedden, the Bridge Project Manager for this project and Bridges & Structures National Discipline Leader at Colliers Engineering & Design.

The I-69/I-475 interchange project is a shining example of how innovative engineering solutions and strategic collaboration can transform critical infrastructure, ensuring safer and more efficient travel for the community. This landmark project not only addressed immediate transportation needs but also set a precedent for future infrastructure improvements across Michigan.