The Massachusetts electricity provider NSTAR—which transmits and delivers electricity to more than 1 million electric customers in 81 communities in eastern and central Massachusetts—recently switched on a large underground transmission line, which the company hopes will ease congestion and help keep costs down for customers.

The 18-mile high-voltage transmission line is one of the largest electric infrastructure upgrades in the history of the United States’ utility industry. Construction on the $220 million project began in the spring of 2005. The new 345,000-volt (345 kV) line will allow NSTAR to tap into electricity resources in southeastern Massachusetts and Rhode Island. It also will help ease bottlenecks, therefore helping to control costs.

The route stretches from the town of Stoughton to Hyde Park, with a second line to south Boston.   EC