PITTSBURGH — If you’re headed into downtown Pittsburgh from the South Hills, and depend on the T’s red line to get you there, your commute will be changing. Starting Sunday, the red line from Overbrook to South Hills Junction will be closed entirely as part of a $150 million construction project. Construction crews were already at the Overbrook junction days before it’s scheduled to close for most of the summer. The red line construction is the second part of Pittsburgh Regional Transit’s light rail rehabilitation project. The start of the closure comes on a busy weekend — as Juneteenth activities are kicking off downtown. The project is scheduled to last until 2028.