JamesRowden
Established Member
If you consider the number of trains that pass between Paddington & Airport Junction (including FGW services etc), that electrified portion of line can't see that much use as a percentage diesel v electric services compared with other lines.
Speaking of Airport junction, a very short stretch of the GWML fast tracks directly West of Airport junction has wires but no electric services use it. I would guess that it was placed there when the line to Heathrow was built/electrified so that when the GWML is electrified less modification to the junction would be required.