Campaigners want Network Rail to remove metal gantries in an Area of Outstanding Natural Beauty (AONB) they call an "ugly scar on the landscape".
The "huge metal goalposts" installed near Goring Gap in the Chilterns, are the latest step in the electrification of the Great Western Railway.
Residents claim they have not been properly consulted.
Network Rail said it was "working actively" to address any concerns through a series of drop-in sessions.
Lucy Murfitt from the Chiltern Conservation Board said: "What Network Rail are doing is pretty much vandalism.
"There is legislation in place that is supposed to protect AONBs and we'd like to see Network Rail modify their designs to reflect that."
Rail operator Network Rail is undertaking a major, 10-year modernisation programme on the line at a cost of up to £1.74bn.
This includes upgrades to stations and electrification of parts of the route, including the section between Reading, Berkshire, and Didcot, Oxfordshire.
Ian Haslam from the Railway Action Group said it "fully supported electrification", but that there were "less visually intrusive designs" available.
He added: "Basically, this is the design they are going to be using from London all the way to Bristol, and they are not changing to take any regard of the beauty of the landscape."
A Network Rail spokesman said: "We are delivering the Great Western Electrification Programme through our permitted development rights.
"Notwithstanding this, we are fully aware of the concerns raised by residents in Goring and are working actively to address these through a public consultation."
He added a series of drop-in events will start on 23 October, featuring information about the current design of the overhead line equipment, other designs considered and options for possible "mitigation measures".