Marion & Wareham, MA Route 6 Bridge Replacements
Marion & Wareham, Bridge Replacements
Industry: Transportation Infrastructure & Bridge Construction
Start Date: March 26, 2025
End Date (Anticipated): September 10, 2028
U.S Route 6 is a vital transportation corridor linking Providence, Rhode Island, with Cape Cod and other communities along the southern Massachusetts coast. At Wareham and Marion, the road crosses the Weweantic River via two adjacent bridges.
The Route 6 Marion/Wareham bridges, along with the nearby causeway, require significant upgrades. The Massachusetts Department of Transportation (MassDOT) selected Northern Construction and lead designer Benesch to replace both bridges. The work involves marine construction within a sensitive coastal river environment, which requires careful planning and coordination between multiple stakeholders and project teams.
The Scope of Our Work
The Route 6 Marion/Wareham bridge replacement project is a $68.99 million design-build contract to replace the M-05-001=W-06-013 and W-06-016 bridges over the Weweantic River. The involved roadways are highly traveled commuter routes that see regular influxes of seasonal coastal visitors. The new bridges are required to have a 75-year service life.
Key Elements of the Project
Alongside the demolition and full replacement of the Marion/Wareham bridges, the Route 6 work encompasses a number of surrounding projects, including:
- Roadway reconstructions
- Drainage and utility improvements
- Causeway reconstruction
- Retaining walls
- Shared-use paths
Throughout the project, the team must maintain vehicle, pedestrian, bicycle and marine traffic access through a constrained transportation corridor. The highly sensitive environment surrounding the job site is an additional variable that requires extra attention.
An Innovative Design-Build Approach
The initial MassDOT RFP included concepts for the Route 6 bridge replacements. However, the Northern Construction and Benesch teams worked together to develop alternative technical concepts (ATCs) that redesign, simplify and streamline the new bridges while maintaining the integrity of the design.
- The Marion bridge’s original concept called for a two-span structure supported by an in-water center pier. The new ATC includes a 125-foot, single-span prestressed spread box-beam bridge that does not need a center pier.
- The Wareham bridge’s initial design proposed a three-span structure, which was reduced to a two-span spread box-beam bridge, eliminating the planned west pier.
By implementing the ATCs, we create a more unobstructed channel, which facilitates easier water traffic. Additionally, we avoid multiple in-water marine construction activities. As a result, we can limit the handling of contaminated soil and lower subsurface, scour and schedule risks across the project.
Reducing Construction from Three Stages to Two
During the bridge redesign, we recognized that there was an opportunity to further streamline the construction process, reducing what was originally a three-phase process to two phases.
The initial process required the team to construct one side of the roadway and bridges, shift traffic, complete the opposite side of the bridges and then return to the previous side to finish a permanent shared-use path. As the design developed, however, we adjusted the roadway alignment along with the bridge, retaining wall and shared-use-path geometry. By doing so, we can complete the shared-use path as part of the first construction phase.
By simplifying the construction process, we eliminate substantial temporary work and notably avoid multiple additional traffic shifts. The simpler sequence makes scheduling more efficient and reduces risk to motorists and construction crews.
Unique Project Challenges and Solutions
Protecting a Coastal Ecosystem
The bridge replacements are occurring in the heart of the Wewantic River, which is home to coastal wetlands and salt marshes. All work must be completed with the safety and preservation of these ecosystems in mind.
Notably, the area of the bridges is part of a state-listed northern diamondback terrapin turtle habitat. Therefore, we were required to develop a formal diamondback terrapin protection plan as part of the project. Northern Construction worked closely with MassDOT, Benesch, Oxbow Associates, and MassWildlife’s Natural Heritage and Endangered Species Program as part of this process. Features of the plan include specific exclusion barriers, barrier monitoring, worker education and oversight from qualified environmental personnel.
After the project began, diamondback terrapins entered portions of the work area and our teams discovered nesting activity. As a result, we had to adapt our work processes to avoid disturbing these areas. We continue to conduct extensive oversight of diamondback terrapin activities around the project and proceed with work in unaffected areas, where possible. This requires the project to have a high degree of flexibility to ensure we can continue work even if new habitats emerge.
Coordinating Construction and Design
Given that the Marion/Wareham bridge replacement project involved considerable design adaptations and environmental considerations, it is essential that Northern Construction and Benesch maintain close and active cooperation throughout the project.
From the outset, we conducted formal constructability reviews that incorporated construction input directly into design development. As the work progresses, our structural, highway, traffic, geotechnical, marine, survey and environmental teams continue to work together at all levels. By doing so, we’re able to easily address changes in field conditions and maintain the project’s safety, quality and environmental standards.
Maintaining Access Through a Constrained Corridor
Throughout the bridge replacement project, Route 6 must remain open to marine, vehicle, pedestrian and bicycle traffic. We implemented limited work zones that enable regular activity to continue as unimpeded as possible while the work is in progress. Material delivery is also carefully planned so work can continue with little to no disruption. Any adjustments to traffic flow or construction processes also account for the project’s special environmental considerations.
Project Takeaways Highlights & Takeaways
The Marion/Wareham Route 6 bridge replacements are a clear example of a project that includes multiple complexities, but that can be streamlined through careful planning and coordination.
By implementing new ATC designs for both bridges, we were able to evolve the original concepts into simpler designs that maintained rigorous quality standards. We also streamlined various construction processes to lessen disruptions to regular traffic and reduce the impact on the surrounding environment and ecosystem.
As construction continues, Northern Construction remains focused on delivering durable infrastructure that will serve the surrounding communities for decades to come.
WORKING TOGETHER WITH ENGINEERS
We partner closely with engineers to bring their designs to life. We’re pre-qualified with multiple agencies to create an efficient proposal process.
Safety and accuracy are our top priorities. When you work with Northern Construction, you can trust that we pay close attention to every detailed specification and requirement.
SAFETY FIRST
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