The forecast and what happens are different things.
Environment Canada that by 5 pm, even though Ottawa often gets bigger snow falls than Toronto, that they Ottawa only got 18 cm - the lowest in southern Ontario. Compare to the Toronto area which is the highest in southern Ontario (at 32 cm to 53 cm). See
https://weather.gc.ca/warnings/weathersummaries_e.html#ON
Snowfall amounts in centimetres as of 5:00 P.M. EST January 15th
unless otherwise noted:
Scarborough North 48-53 (3:00 P.M.) *
Markham 45 (2:30 P.M.) *
Brampton 43 (11:00 A.M.)*
Pickering 40 (4:00 P.M.) *
Brampton 38 *
Toronto North York 35-38 (2:30 P.M.) *
Toronto Downsview 37.4
Guelph 35 (1.00 P.M.) *
Whitby 32-35 (12:00 P.M.) *
Scarborough Southeast 32 *
University of Waterloo 29 *
Kitchener Stanley Park 27 *
Saint Catharines 27 (1 P.M.) *
Ajax 26 *
Courtice 25 (3:00 P.M.) *
Kingston 25 ^
Oak Ridges 23-25 (3:00 P.M.) *
Scarborough South 25 (12:00 P.M.) *
London 15-25 *
Bowmanville 24 (12:45 P.M.) *
Elora 24 ^
Toronto Beaches 24 (3:00 P.M.) *
Toronto Midtown 23 *
Egbert 22 ^
Peterborough 22 ^
Toronto Pearson Airport 22
London 21 ^
Oakville 21 (2:30 P.M.) *
Toronto Downtown 21 (3:30 P.M.) *
Trenton 21
Uxbridge West 21 ^
Kemptville 21 ^
Mount Forest 19 ^
Hamilton 18 *
Ottawa 18
Metrolinx/Mosaic contracted TTC to operate the streetcars. They have contracted others to do maintenance, like clearing snow, switches, etc.
As TTC was operating (at least some) of the Line 5 trains today, this doesn't see to be anything to do with TTC risk adversity.
