There is some confusion here.
I've made hundreds of trips on the Hill and worked 100s of hours on snow removal equipment, so let's define some terms, at least as I have heard;
A snow plow, pilot plow, rotary plow or snow blowers are different things.
"Snow blowers" is a term I've never heard when working and unless it is another name for a rotary I've never seen one or run one.
A "snow plow" is ancient technology, but still used here and there on short lines. It is a scoop shaped wedge on wheels pushed by a locomotive. Here there are two types; the header plow and or bucker plow. Very inefficient and prone to derailments.
Then there are the rotaries. Amazing. 150' rooster tail when plowing. SP added wings to their rotaries so that they would make a larger cut. These needed pusher power in the middle of a consist with one rotary on one end and another on the other end. That way you can plow in either direction.
But the war against the winter elements is fought in stages. Separate battles, if you will.
In lightest snows, a MOW ballast regulator may be used.
Pilot plows,( a "pilot plow" is that scoop on the front of a locomotive) do a great job, but only to an extent. They leave a core behind and do not go as low as the top of the rail. Core gets too deep amd it can lift the cutting lever and uncouple the cars. That is when you send in the flangers.
Flangers have two blades underneath, one which throws to the right, the other to the left. Very rough ride. No springs, so it doesn't bounce, because the blades extend below the top of the rail to keep the inside of the track free of ice, which could cause a derailment. But these leave a core behind as well, just wider. Now you need the "spreader."
The spreader is equipped with wide, hydraulic powered wings that can extend out to 15 feet on either side of the track to clear a up to a 30' swath. They push the snow down the hill or, if you must, pack the snow against a cut or cliff or some other place with limited side clearance. But you can only pack so much snow into a given space.
When you run out of room you make the last ditch effort and put a rotary to work, with its wide wings to clear all the packed snow out.
Good question. Thanks for asking.