I am experiencing an issue where the shadows cast by the wires strung between telephone poles have these strange squares embedded in them. Are there any known fixes for correcting this?
It is an optimization, shadow quality issue. Plus I noticed (with trees) that a lot of objects don't directly have shadows. Old trees, specifically (they do have different shadow from their current model - usually the branches without leaves). Mind you this route (and its assets) was released early 2008, compromises have been made. It has been slightly upgraded for 2012 but a lot of things did remain as they were. These routes are generally good for budget computers and high frame rates. You could try and replace the wires, although probably not worth it. There are, however, workshop updates to Cajon Pass. Chances are there are updated models for the poles & wires somewhere. Given it's an American asset, RailWorks America may have something. Ask the same from AI, you may get direct links. Gemini was able to analyse my screenshots quite well.
Those pole are most likely made a long time ago and made with planes and alpha channels. You could replace them with newer models. All you could want in newer Telegraph and Power Poles can be found right here.
As the OP is a new member he might not have the skills to replace them. I've only been playing the game since 2012 and I would not know how to do it
Those BDW power poles look good, I think something called 'rwtools'??? is used to do a global replace in a route? I did this once to replace some track with ScaleRail but it's been awhile.