Josh Cone-Roddy, PE, Director of Highway, VHB
The I-495 and I-90 interchange is one of the busiest and most critical junctions in Massachusetts, serving as a vital link for commuters and freight traffic. However, it has long been plagued by congestion and safety issues due to substandard geometry and a bottleneck at a defunct toll plaza. Recognizing the need for improvement, the Massachusetts Department of Transportation (MassDOT) embarked on a transformative project to enhance mobility and safety at this interchange.
Project Overview
The 495/90 Interchange Improvement Project is a comprehensive effort to address the interchange’s geometric and operational deficiencies. VHB, in collaboration with Design-Build (DB) partners Barletta, O&G, and Aetna Bridge, has taken an integrated approach to redesigning the interchange. This project leverages the experience of highway, traffic, and structural engineering professionals while navigating complex environmental and regulatory requirements.
Environmental Considerations
The project spans environmentally sensitive areas, including wetlands and floodplains. VHB’s team utilized advanced technologies like HydroCAD and HEC-RAS to model environmental impacts and devise solutions that preserve existing ecology while establishing new wetlands. This approach complies with state and local environmental regulations and improves runoff conditions for over 650 acres of roadway.
Innovative Design Solutions
A key feature of the project is the redesign of two of the highway ramps that border sensitive environmental resource areas. The DB team introduced an alternate technical concept (ATC) that allows for over six acres of wetland restoration and reduces stormwater impacts by minimizing impervious cover. Additionally, the project includes 12 bridges and 32 walls, with enhancements to increase lifecycle, save costs, and reduce environmental impacts.
Traffic Management and Public Engagement
Maintaining traffic flow during construction is a significant challenge. The project team has designed temporary lane shifts and ramp alignments to facilitate travel while ensuring safety. A Real-Time Traffic Monitoring (RTTM) system provides travel time and speed information to the public. Public engagement has been integral, with VHB and our partners RVA leading efforts to liaise with the community and build support for the project.
Conclusion
The 495/90 Interchange Improvement Project exemplifies the DB team’s commitment to enhancing infrastructure while respecting environmental and community needs. Through innovative design and strategic collaboration, this project will significantly improve safety and mobility for Massachusetts drivers, setting a new standard for future infrastructure projects.