https://www.openstreetmap.org/way/1396730552 turn lanes are not modelled like that, we only draw a separate way where there is physical separation, if there's just paint on the ground it's best to use the turn:lanes tag https://wiki.openstreetmap.org/wiki/Key:turn#Indicated_turns_by_lane to specify the turn lanes.

The existing way at https://www.openstreetmap.org/way/40427397 already allows for routing from Spencer Street turning right into Gatton Showgrounds.