Today's glorious sunny Spring weather encouraged me to head west - to the edge of my 5km COVID zone.

First pic shows 207, the tram that took me to Gordon St, heading south out of my zone.

Can anyone tell me what those white circular things about the size of a tin of shoe polish and attached to the tram stop sign are?

Second pic shows 154 turning from Gordon St into the reserved track beside River St.  The apartments in the background are on the site of the old Ammunition Factory.

The pic at https://tdu.to/i/74203 ; shows roughly the same spot.

Mal Rowe - western suburbs person