(AP) PPL Corp. said Thursday it wants to spend billions of dollars to build a 725-mile system of electric transmission lines that will bring energy from the booming Marcellus Shale natural gas fields to customers on the heavily populated Eastern Seaboard. The Allentown-based utility said the 500-kilovolt line would span much of Pennsylvania and reach into New York, New Jersey and Maryland, although the route has not been determined. The cost was expected to exceed $4 billion, and it could take more than a decade to build. A rough map produced by the company shows a line running from Pittsburgh through Pennsylvania’s rural northern tier and into the New York City region. A second line branches south through the Susquehanna River corridor into Maryland, while a third spur runs through the Lehigh Valley and Pocono Mountains into central New Jersey.