At the heart of Rhode Island’s transportation network, the Providence Viaduct plays a vital role in connecting people, communities and commerce along Interstate 95.

Spanning Route 6, the Woonasquatucket River, Amtrak’s Northeast Corridor and local streets, the northbound structure is a gateway into Providence and a critical junction where regional, local and interstate travel intersect. Each day, more than 220,000 vehicles move through this corridor, as one of the most heavily trafficked highway bridges on the East Coast.

The Rhode Island Department of Transportation’s (RIDOT) Providence I‑95 Viaduct Northbound project redefines how this essential connection serves today’s travel demands. By replacing the 1,295‑foot bridge and introducing a new system of ramps and collector‑distributor roadways, the project creates clearer, more intuitive movements along I‑95, the 6/10 Connector and Route 146. The redesigned network enhances safety and efficiency while reducing congestion and creating a more comfortable, predictable driving experience for motorists.

Beyond the physical transformation, I‑95 Viaduct Northbound project reflects a collaborative and innovative design-build delivery approach, which accelerated delivery by a full year and reducing overall costs.

HNTB served as lead designer for the I-95 Viaduct Northbound project, led by the Skanska-Manafort Joint Venture. The firm provided civil and utility engineering, structural and geotechnical design, environmental services, traffic analysis and other project support.

“We wanted the transition to the new viaduct to feel intuitive and effortless, with no abrupt lane shifts and no confusing merges. That was our goal,” said Michael Beintum, HNTB bridge task lead. “Every movement was engineered to enhance safety and fluidity while minimizing disruption. When drivers don’t notice the bridge, it means we’ve done our job right.”

Unlocking the interchange 

From the outset, the design‑build team approached the project as more than a straight replacement. Early collaboration between RIDOT, Skanska‑Manafort and HNTB created the trust and transparency needed to challenge assumptions in the base technical concept and to look for opportunities beyond the project’s initial boundaries.

The design-build team proposed an alternative technical concept that reshaped the project’s trajectory by addressing challenges beyond the original scope. Central to this approach was the complete replacement of the Route 146 Bridge over mainline I‑95, located nearly a mile from the viaduct itself.

“Design‑build gave the team the flexibility to challenge the original assumptions and unlock a better solution,” Stephen DelGrosso, vice president of operations at Skanska USA. “Replacing the Route 146 Bridge wasn’t in the original scope, but it was essential to creating a safer, simpler interchange. That kind of innovation only happens when the entire team, including the owner’s team, is aligned around the common goal to improve long‑term performance.”

Although not included in RIDOT’s original program, replacing the bridge proved essential to untangling the interchange’s most complex movements. By removing this constraint, the team was able to lower the viaduct to a single elevation, simplify geometry and eliminate unnecessary layers of structure.

“The base technical concept relied on a multilevel configuration within an already congested interchange,” Beintum said. “Replacing the Route 146 Bridge gave us the flexibility to rethink the system holistically and design a safer, more intuitive corridor.”

The reconfigured layout introduced new northbound I‑95 on- and off-ramps and shifted Route 146 traffic to a collector‑distributor roadway. In doing so, the team eliminated two of the four ramps originally proposed, streamlining driver decision‑making and reducing potential conflict points.

“The objective was to create a true collector‑distributor roadway that simplifies how traffic enters and exits I‑95,” said Alexandra Siu, HNTB deputy design manager and traffic task lead. “By untangling these movements, we were able to minimize lane changes, which reduces congestion and enhances overall safety.”

With the design solution established, attention turned to one of the project’s most consequential challenges: moving traffic safely through construction. The original staging plan required shifting high volumes of traffic onto aging sections of the existing viaduct’s median.

To eliminate that risk, the team reversed the sequencing strategy. Rather than relying on the existing median, crews demolished it and rebuilt the median first to support all four mainline lanes of traffic. Once complete, traffic shifted onto the new median, allowing construction of the outside lanes to proceed without interim repairs or temporary fixes.

This revised design solution and construction sequencing reduced disruption for motorists, simplified construction and ultimately saved a full year on the schedule while lowering project costs by approximately $1 million.

Below and beyond the roadway 

Beneath the I‑95 Viaduct Northbound lies a dense network of aging utilities and soft soils — conditions that posed significant risks to both stability and schedule. RIDOT’s net‑zero loading requirement further shaped the design approach, encouraging solutions that minimized the structure’s impact on the ground below.

To address these site complexities, the team turned to foam glass aggregate, a lightweight, recycled material that performs like gravel under load.

“Traditional fill would have increased the risk of settlement,” said Matthew D’Angelo, HNTB design manager. “Foam glass aggregate allowed us to minimize weight while maintaining strength, making it ideal for utility‑dense and soft‑soil zones.”

The material reduced loading, improved ground performance and supported a more sustainable subsurface solution, critical advantages on a site where every condition was interconnected.

Above ground, the team navigated an equally complex environment while working over the Woonasquatucket River and Amtrak’s electrified Northeast Corridor. In close coordination with Skanska‑Manafort, HNTB led early and ongoing engagement with Amtrak, delivering design modifications to the overhead catenary system and ensuring safe clearance throughout construction while maintaining uninterrupted rail operations.

A clearer gateway

With construction complete, I‑95 Viaduct Northbound stands as one of the largest design‑build projects in RIDOT history with a reimagined approach to regional connectivity. By innovating beyond the base technical concept, the project team delivered a safer, more efficient corridor that strengthens Rhode Island’s transportation backbone for years to come.

“This wasn’t just a viaduct replacement. It was a complete rethink of how travelers move through one of the most challenging interchanges in the state,” said Anthony Pompei, RIDOT project manager. “The result is a clearer, more reliable connection that will serve Rhode Island for decades to come.”