Gonzo,
It is required for <550 metres and LVP. For LVTO you're already well and truly in within LVP minima. Our transmissometers are approved for fog and most only. If visibility is reduced due to rain or dust, the ILS is CAT I only.
As LVP applies are implemented over the entire airfield, there are times when some taxiways will be obscured but the runways visible to the tower. In this case there are local procedures to handle vehicles.