The project gets underway tonight.
Most nights during the project, officials say drivers should expect only 1 lane of traffic. Backups are likely. During the day all four lanes of the highway will be opened, however there won't be any shoulder along the 6-mile stretch heading north from the Mid-County interchange.
With 65,000 vehicles roaring along the stretch of highway, it is the busiest stretch of 4-lane road on the Pennsylvania Turnpike's system.
Friday, officials held a ceremonial groundbreaking.
"It will be two 12-foot lanes, which is what it is now," said Richard Cochrane who is the expansion project's manager. "However, there will be a barrier along the right shoulder that motorists will notice. So, there's less room for error."
The cost of the first part of the project, 6 miles worth of highway, is just over $150 million.
"That's $25 million a mile," said Frank Kempf, chief engineer for the project. "It was a time, in the not too-distant past, when you could build a brand new road for a million dollars a mile."