The property behind mine has an easement over my property for road
access.  There are no documents describing this arrangement in detail
other than reference to the town hall map on my deed.

The main question is: who needs to pay for snow removal on this
driveway? My neighbor claims that I have to keep the road "egress
free" which she interprets as that I should pay for snow removal. I
disagree.

Another question that would be great to get some advice on: According
to the local (and old) land surveyor, the original easement given was
16 feet wide, the previous owner of my house had a deed that said the
easement was 20 feet wide, and the town records office's map says the
easement is 25 feet wide. Unfortunately, the land surveyor does not
have any documents that say 16 feet. The 25 feet apparently come from
the fact that a "standard" easement (given no other specifications) in
the state of Connecticut is 25 feet. The current driveway is probably
about 12 foot wide but I would very much like to not have this
expanded.

When you bought the property many years ago, you and/or the seller
likely paid for a survay, title insurance, and a commission to a
realtor and/or a lawyer. All of these are obligated to give you at
least an opinion at no cost.
The persons who represented the purchase by your neighbor are also
obligated to give you free information.
If you make occasional use of the easment driveway, it would be fair
for you to pay a proportional cost for the snow removal. If you do not
use the easement driveway, even in summer, my guess is you can reguard
the snow as an act of God, and refuse to pay for it's removal. If your
finances allow you to be charitable, I suggest you make any reasonable
compromise to keep peace with your neighbor.  Neil

Thanks for your comments. I do not use the driveway and don't find the
need for charity particularly appealing given that the house behind
mine is worth approximately 2x what mine is worth. What did you mean
by "acts of God" as it relates to snow? I'm hoping for some reasonably
clear answer to whether or not I have to pay for snow removal given no
mention of it in any documents.