Yep, there is a missing connection in the SE quadrant at Doncaster, which would link the York and Bala Subdivisions. Therefore, your train had to first pass pver the Doncaster Diamond (i.e. from East to West), then back onto the Bala Subdivision (i.e. from West to North) and then pass a third time through Doncaster (i.e. from North to South):
Something very similar happens every time Train 1 leaves Toronto towards Vancouver, which has to back at Snider from the North to the West in order to proceed from the South (Union Station) towards the East (Doncaster):
The train already arrived Oshawa 43 minutes late and arrived at Union exactly 90 minutes late, meaning that it lost 45 minutes during the detour, which is really not that bad considering that the York and Bala Subs are mostly single-tracked and require a backup move inbetween:
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