U.S. Department of Transportation Secretary Ray LaHood traveled to Pittsburgh Friday to endorse a NiSource Inc. project aimed at replacing more than 1,000 miles of corroding pipeline.

NiSource, the Merrillville, Ind.-based parent of Columbia Gas, said its Columbia Gas Transmission subsidiary was launching a program to upgrade 12,000 miles of interstate pipelines transporting natural gas across the Midwest and Mid-Atlantic regions.

Industry activity is accelerating the need for repair, the company said.

The updated pipelines cross six Appalachian and Mid-Atlantic states, and cut through areas where drilling for natural gas in the Marcellus Shale region has forced a renewed emphasis on having a stable infrastructure.

Pipelines in the region now are more than 40 years old, the company said.

NiSource said it expects to invest $4 billion over 15 years in the project, which it estimates will produce up to 8,000 direct jobs. Pennsylvania will see about $400 million of that investment each year for about the next five years, the company said.

Standing alongside Pittsburgh Mayor Luke Ravenstahl, a Democrat, and U.S. Rep. Mike Doyle, D-Forest Hills, Mr. LaHood pledged to expedite the process.

He has made pipeline safety a priority of his tenure at the department, working under Democratic President Barack Obama's executive order to "Improve Performance of Federal Permitting and Review of Infrastructure Projects."

More than 2.5 million miles of pipeline deliver oil and gas across the country, and April is actually National Safe Digging Month.