Late nights Monday, September 27 until Thursday, September 30, Line 1 Yonge - University subway trains in both directions operate along the southbound tracks only between Vaughan Metropolitan and Pioneer Village stations, while TTC crews repair a leak on the northbound tracks. Regular service resumes by 6 a.m. each morning.
(Since the single-track operation occurs after midnight each night, technically, the closure is from Tuesday, September 28 until Friday, October 1.)
During single-track operation, both south- and northbound trains alternate along the southbound tracks.
You must board northbound trains on the southbound platforms at Pioneer Village and Highway 407 stations. You may also have to wait for trains longer than usually.
Note also that, further southward on Line 1, the TTC is cancelling subway service between Sheppard West and Wilson stations after 11 p.m. Monday, September 27 and Tuesday, September 28. Transfer to shuttle buses to travel between the stations.