So the conclusion that I draw when comparing those 3 sets of data is that there is no reliable relationship between attenuation and road distance to the exchange.
Correct. Other than a very broad "rule of thumb", to be taken with a big "pinch of salt".
So why even begin to associate straight line distance and road distance with attenuation......it may as well be the number of lamp posts between you and the exchange.
Logically the further you are from the exchange, the more lamp posts, cats eyes in the road (apologies bc), telephone poles etc etc. there will be.
Just a little food for thought..............
Logic, BT and ISPs don't always fit nicely in the same sentence.
I think attenuation AND physical distance from the exchange/cabinet need to be considered together.
e.g. Using the Kitz ADSL calculator, a DS attenuation of 30dB suggests an
Approx Line Length of 2.2 km.
If a given user knows (for a fact) that their own line length is say, only 1000m, but they are seeing 30dB DS attenuation, it
could indicate a severe, repairable fault (High Resitance etc.).
It may just be that their connection includes a lot of aluminium cable, or the copper has corroded down in thickness over time (in which cases there would be very little, if anything, the user could do about it).