PJM Interconnection, the regional power grid operator, on Wednesday authorized more than $1.5 billion in electric transmission projects in its region encompassing 13 states and Washington, D.C.

The largest project, proposed by Public Service Electric & Gas in New Jersey, addresses aging infrastructure in Burlington, Mercer, and Middlesex counties, requiring a rebuilding of portions of existing transmission lines in the Metuchen-Edison-Trenton-Burlington corridor.

The transmission system upgrades are typically completed within five years of authorization, said Susan Buehler, PJM's spokeswoman.