Nick14
When there is runway with multiple RVR measurements the required RVR shall
be:
1. For 2 (two)measurements:
First part as per landing minima;
End of runway as per takeoff minima.
2. For 3 (three) measurements (usually when runway is more than 2000m length):
First part as per landing minima;
Middle part as per take off minima;
End of runway should be taken into account for information.
Then of course you have to account for runway lighting facilities.