By CBS3 Staff

PHILADELPHIA (CBS) — Commuters be warned. SEPTA’s annual repair blitz starts Friday night.

The Trolley Tunnel Blitz will shut down the Center City tunnel for 17 days starting at 10 p.m. on Friday.

Crews will work around the clock to fix wires, replace worn tracks, and doing maintenance.

They will also demolish and rebuild the eastbound 22nd Street platform.

SEPTA says it schedules the blitz during the summer when ridership is at its lowest.

The tunnel reopens on July 26 at 5 a.m.