I think it would be unlikely to be a byelaw, but there may be Road Traffic laws. If you are in a controlled parking zone, there will be signs to this effect on every entry into an 'area'. These will say 'Controlled Parking (or Waiting) Zone', with a 'No waiting' sign on (blue circle with red border and red slash across) and will indicate vehicles affected and times of operation. On the back of the sign it should say 'Controlled Zone Ends' so you know when you are driving out of it. Weight restictions are denoted by the normal red circle with '7.5t' (or whatever) to indicate the gross weight limit.