>>2056360
The Harton Electric Railway had low voltage (550V DC) so low clearances needed. Seems like the North East was a hotspot for electric railways.

https://www.youtube.com/watch?v=Kom4AaeLnlc

Now you can get insulation coatings that allow you to drop clearance requirements by a lot. In the Great Western Electrification Programme they managed to save £39m by doing this under a bridge in Cardiff compared to raising the bridge above the railway. Clearance is now 20mm to the bridge and 70mm to the train roof, whereas it would be 370mm normally.
>https://www.modernrailways.com/article/gwep-home-straight
>https://epc.ac.uk/article/case-study-affordable-railway-electrification/