Cable route who knows but I would think it goes the long way round following the main roadIf I understood your earlier post correctly you're saying you're modem reports 10db attenuation at the moment. That equates to 800m. But I'm not sure what you mean by your sync speed is 15000643 down. Is that supposed to be 15Mb/s? 15Mb/s would be more like 2km of cable. 10db attenuation would normally see you getting 24Mb/s.
Stats taken from a Draytek 2820 router
I believe that the rates are in B/s I also suspect that the copper has some issues on the BT network.
Bit of history on line internal phone wiring is fine I had an original BT engineer install when ADSL first came out 0.5meg service on the old stingray USB modem
Upgrade to 2Meg ADSL
Upgrade to 8Meg ADSL (first router would sync at full speed) on a Draytek 2600
Second router I had would sync just under full speed on a Draytek 2800
At some point I upgraded to a Draytek 2820
Upgrade to ADSL2+ had SNR sync dropped at DSLM and would sync at around 18Meg LLU
6 months later had issues with stability and had SNR reset would sync at around 16Meg
I have also had a bad fault on the line at some point in the past which caused my sync to drop to nearly zero and had major impact on voice calls such as crossed line and line noise which was sorted by changing the pairs on BT network