UI to Complete over 7 Miles of Transmission Lines and Major Progress on Critical Substation in Bridgeport

Progress in 2025 will rebuild aging grid and protect major transmission substation against flooding to increase reliability

ORANGE, Conn. - November 6, 2025 - Today, United Illuminating (UI), a subsidiary of Avangrid, Inc., announced the company is on track to invest more than $217 million in transmission line rebuilds and a transmission substation floodwall, which are key projects to protecting the reliability and resiliency of the regional transmission grid. By the close of 2025, UI will have rebuilt 4.1 miles in the Derby Junction to Ansonia transmission line rebuild project and 2.6 miles in the Milvon to West River transmission line rebuild project. Another 2.9 miles of the Milvon to West River project is under construction this year and is expected to be completed in early 2026. Also in 2025, UI began constructing the Singer Substation Floodwall, a $47 million infrastructure investment that will protect the reliability of Singer Substation, a transmission substation located in Bridgeport. The floodwall is expected to be completed in 2027.

"New England's electric grid is only as strong as the transmission system that comprises its foundation," said Frank Reynolds, President and CEO of UI. "At UI, I'm very proud of a team that is wholly committed to ensuring the reliability and resiliency of the small portion of the transmission grid we oversee. Because much of this infrastructure is many decades old, we are working with state agencies to ensure it is replaced before the point of failure, and I look forward to seeing that work continue into next year across our service area."

Construction began on the Derby Junction to Ansonia transmission line rebuild project in March of 2024 with the goal of replacing 4.1 miles of transmission infrastructure that had served the region since the 1920s. The region is known as a load pocket, meaning that the loss of these transmission lines, would result in loss of power to the substations that feed customers in Derby, Shelton and Ansonia. Combined with the critical facilities in the region, such as Griffin Health Hospital in Derby, the load pocket makes the transmission rebuild and replacement even more timely and essential.

As part of its Railroad Transmission Lines Upgrade program, UI has completed construction and put into service 2.6 miles of double circuit monopole assets for the Milvon to West River phase of the program: two 1.3-mile segments running from West River to Allings Crossing, the most recent of which was put into service in April 2025. Through year-end, UI is continuing construction on the next 2.9-mile segment (Allings Crossing to Woodmont) and anticipates it will be in service in Q1 2026. All four segments of the Milvon to West River project, which comprise a total of 9.5 miles of work from New Haven to Milford, is expected to be completed in mid-2027.

The Singer Substation Floodwall is a $47 million investment in the resiliency of the transmission system in Bridgeport and for the entire New England system. Following flooding in the area due to Tropical Storm Irene in 2011 and Superstorm Sandy in 2012, UI proposed a comprehensive flood mitigation strategy for its coastal substations, including Pequonnock Substation, Congress Street Substation, and Singer Substation, all in Bridgeport, as well as the Grand Ave/Mill River Substation in New Haven. For Singer Substation, UI determined that the most prudent option was to install a floodwall around it. Construction on the floodwall began in May 2025 and will ultimately reach 17 feet high, with king piles up to 42 feet deep in the ground. The project is expected to be completed in the first quarter of 2027.

"Reliability and resiliency go hand in hand," said Chuck Eves, Vice President of Electric Operations and Projects at UI. "When we make the necessary investments in modernized, upgraded infrastructure, our customers experience higher-quality power and fewer outages, including during storms. At the transmission level, this is even more important, because outages can impact both our local customers as well as 14 million electric customers across New England. Our investments in the transmission system will continue as we look to ensure the strength of the critical portion of the grid we oversee."

For more information on the Milvon to West River transmission line upgrade project, please visit UI Energizes New Transmission Infrastructure to Strengthen Electric Reliability and Resiliency for Region - UI. For more information on the Singer Substation Floodwall, please visit UI Breaks Ground on Singer Substation Floodwall - UI.