Project Overview
Situated in southeast Maine, the Blue Hill Falls Bridge is a historic structure that has served travelers since 1926. For generations, the bridge was enjoyed by the community, serving as an inspiration for artists, a destination for kayakers and wake boarders, and a treasured asset for locals. However, after decades of use, the Blue Hill Falls Bridge was in desperate need of replacement. To help determine the best path forward, the Maine Department of Transportation (MaineDOT) partnered with an advisory committee to explore design proposals for the new bridge. Ultimately, the group decided to replace the arched structure with a precast, prestressed concrete girder bridge, a structure that promises a longer service life and reduced maintenance requirements, and a sustainable solution that’s built for the future.
A Historic Undertaking
To honor the historic Blue Hill Falls Bridge and the many residents and visitors who enjoy it, the design team, along with MaineDOT, took steps to ensure that the new structure contained elements from its past. During the construction process, general contractor Cianbro Corporation integrated granite stone masonry pieces from the original bridge into the replacement structure. Additionally, to ensure the long-term resilience of the structure, a variety of precast concrete components were specified in the design, including 16 precast concrete approach beams, 5 prestressed Northeast bulb tee (NEBT) girders, and 8 precast concrete arched fascia panels. The bridge was also elevated by 4 ft to accommodate rising sea levels and enhance its resilience.
Joe Carrara, president of J.P. Carrara & Sons, the project's precast concrete producer, explained that the team used accelerated bridge construction methods to expedite on-site work. These methods, in conjunction with the use of precast concrete, limited disruptions for commuters and were more environmentally friendly than traditional bridge-building methods. Additionally, the off-site fabrication of the precast concrete pieces allowed for precise manufacturing, minimizing material waste and mitigating pollution that might have been generated through additional on-site work.
“By incorporating precast, prestressed concrete, the bridge’s structural integrity and construction timeline were optimized,” Carrara said. “This approach also significantly reduced waste and environmental impact, aligning with the sustainability goals that are often prioritized in historic preservation efforts.”
The Blue Hall Falls Bridge is located above saltwater, so the project team also had to consider how to manufacture precast components that will achieve a long-term service life. By incorporating a series of high-strength materials such as 10,000-psi concrete, stainless steel prestressing strands, and ChromX 9100 Grade 100 rebar, the potential for environmental stressors such as corrosion from saltwater was significantly reduced. The enhanced structural integrity made possible by the selection of these materials will extend the service life of the new bridge while minimizing future maintenance requirements and upkeep costs.
While the historic Blue Hill Falls Bridge was a cherished landmark for locals, the new bridge ushers in a bright future for the community, combining durability, aesthetic appeal, and improved functionality for commuters.
“Through leveraging precast concrete and accelerated bridge construction, the Blue Hill Falls Bridge replacement project successfully addressed existing structural deficiencies, improved public safety, and provided a durable infrastructure solution for the public—all with a reduced carbon footprint,” Carrara said.
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |