trambulation

Why is it that when I start to pack up to leave work for the day four trams will pass by my window in rapid succession? They all head citywards – in fact there goes another one – precisely the direction in which I’d like to go.
However, the moment I step out the door the miraculous procession of trams will dry up. Completely. Smith Street will become empty of trams and other tram-like conveyances. There will be nothing but a long cold wait.
This happens with stunning regularity. Do they sense me coming?
I’m a dedicated user of PT but it really is tough love on cold, dark post work evenings.