@sjpowermac I’ve got a few observations to make from quite a few years living less than a couple of hundred metres away from Cowley Bridge Junction.
These are purely anecdotal of course but it may be of interest.
We have quite a decent variety of passing trains and they’re generally accelerating away from Exeter, or slowing down for the station stop (unless they’re running on or off the Barnstaple line).
I can almost always tell what’s passing from the noise because it bounces across the valley, and I’ll run through some of them here:
class 143 - noisy engines, and a good amount of flange squeal as they turn on or off the Barnstaple line, very distinctive.
class 150 - very noisy engines, the sound seems to carry very clearly for quite a while, but no squealing wheels.
class 158 - much quieter than the above!
HST short sets and XC sets - a nice quiet low resonant rumble from the MTUs as they accelerate past, very smooth, and the mk3s are definitely quiet when going over the points compared to other stuff.
IETs - Pretty quiet actually. Slightly louder than the HSTs over the points, but the engines (although at a higher pitch) are quieter (possibly because they’re spread out throughout the sets).
220/221s - The noise of the engines carries quite well, but the noise of the wheels hitting the points of the junction is for some reason far louder than any of the other wheelsets that pass here. They make a real clattering sound.
class 57s on the sleepers - being so late at night the sound carries quite well. They’ve got a nice meaty sound compared to the units.
classes 59 and 66 - That yinging tickover cuts through everything. I can hear them ticking over even indoors, and when they open up with a heavy freight they’re actually quite loud. But not as loud as a:
class 37 - on an NR test train. They are still astonishingly loud, and if the wind is in the right direction you can still hear them growling away for a good few minutes after they’ve gone past.
There’s other stuff too including railtours etc, but these are the most frequent things that I notice day to day.