Hiking in snow

[Stormcrow]

GURPS Campaign, p. 351. "Very bad" terrain includes deep snow and imposes a 20% limit to ideal daily mileage. The "snow" weather condition halves speed when ankle-length or quarters it or worse in deeper snow.

This seems to be double-dipping. I notice that in the third edition Basic Set, there was no "snow" weather condition, though "very bad" terrain still included deep snow.

Is deep snow supposed to be terrain or weather? Or is something else going on here?

P.S.: No need to talk about whether the travel rules are realistic. I've seen the other threads.

[evileeyore]

What I've done is strike the "deep snow" from the Very Bad Terrain.

[Extrarius]

Notice that the 0.2 multiplier for deep snow being "very bad" terrain is effectively one value that fits the description that deep snow-weather "divides speed by 4 or more".

Also, the weather entry for snow mentions that skis effectively change the terrain quality over snow. It seems odd to talk about changing terrain quality in a section that is supposed to be about a different set of modifiers.

These two things lead me to believe that they're both right, but only apply one of the two.

Actually, upon closer reading, that last part is exactly right. Under "Roads":

[...]
In snow or ice, treat roads as Average terrain, but apply the movement penalties given under Weather (above) unless the road is cleared.
[...]

This leads me to think that off roads, deep snow is a terrain condition. On roads, any snow is a weather condition.

[Bruno]

A couple of notes from Real Life.

Walking on well packed granular snow is tiring, the same way that walking on sand is tiring and for the same reasons. Its a granular surface that warps under your feet and skids around and is generally crappy, even if it's not any significant depth or has had all the "fluff" crushed out of it after a few weeks of dry, cold, windy conditions.

Wading through snow is like walking on snow, with the added penalty of wading through stuff. It's not as much extra weight as wading through water, but it has added hazards from the depth being concealed. You'll be walking on a packed layer, and then wading through layers of fresher fluffier stuff.

Snow shoes are helpful for both kinds, but dramatically better for the deep fluffy stuff.

[Ultraviolet]

So, if you're already walking in/on snow - does it affect your walking speed if snow keeps falling?
I haven't trekked in severe snow, nor in any snow for quite a while. But it seems to me that falling snow is bad for visibility. And at walking speed this is less serious than for driving in a car at fair speed.
For walking I'd say the temperature and wind speed means more for walking speed than the amount of snow falling. If snow is whipped in your eyes it's difficult to see anything, and speed should be reduced. If the wind is in your back or flank visibility is less of an issue, but it still may be so cold your body takes a toll and tires quicker.

As for road versus off-road - if the snow is deep enough the difference becomes minor. If the road is even partially cleared or if the wind blows snow off the road, but it gathers on all bumps and vegetation off-road the difference is huge.

So in conclusion, I may apply both modifiers for terrain and weather under some circumstances but not all.

[Bruno]

Originally Posted by Ultraviolet

So, if you're already walking in/on snow - does it affect your walking speed if snow keeps falling?

It makes the snow you're trying to shuffle through deeper as you go, which just makes that situation worse. It prevents heavy foot traffic from clearing an area and can fall much faster than the wind can clear it. If there's sufficient wind blowing to "clear" it, this improvement will be a locallized phenomenon, because the snow blown away from one area doesn't "go away", goes somewhere else (often another road section), where it piles up even deeper.

In large open areas here, we put up "snow fences" at fairly regular intervals to catch blowing snow before it blows too far and accumulates too much at a natural barrier (such as a house, or for various reasons a road) and buries it or creates snow pack on it (which isn't as bad as hitting ice unexpectedly but it's still Real Bad at highway speeds).

"Blowing Snow" is a thing that gets reported on the weather here, and it's usually a sign you need to stay the heck off the highway.

As for visibility: it's just dangerous in a different way for a pedestrian; snow accumulation on paths quickly eradicate them, which means you're going cross country - this means if there's wilderness, you can walk right off a path in the middle of a blizzard and into the wilderness without realizing it. Even getting confused and ending up in a farmers field is bad - you don't have lights on you, and being a tiny human instead of a 2+ ton vehicle, you're hard for rescue teams to find.

They string ropes or chains between buildings in places prone to whiteout conditions so you can hang onto it and not end up walking off a cliff or out onto the tundra or something.

I have both walked and driven in some ridiculous blizzard conditions before, my sense of self-preservation in that regard is super defective. I really don't recommend it, it's a horrible experience.

[Stormcrow]

Blowing snow will certainly affect travel, but the text for both terrain and weather seem to dwell entirely on snow that is already on the ground. I wonder how applicable to the actual rules blowing snow is.

[Celjabba]

Yes, I would say apply either but not both for snow on the ground.
1/5 speed in deep fresh snow (exemple of generic rule for bad terrain), and from half to 1/4 or more in snowy weather (specific rule).
The 2 values don't contradict themselves, imho. The first one is just an applied exemple of the second.

For blowing snow, I would add penalties as for rain (low visibility, wet, cold).

As an aside, here are some anecdotic data :

I don't have any real experience hiking in really deep snow (more than 30 cm) but I have done a few hikes in Finland and low Switzerland in moderate snow condition :

In my limited experience, walking cross-country, the worst is fresh fluffy snow about 10-20 cm deep with a bit of wind.
It is deep enough that you only see an expense of flat pristine snow, but thin enough that your feet can and will trip on hidden holes, rocks, roots and whatever.
More snow, you need to wade in the snow, each step making a deep hole you need to get out of, but uneven ground is (mostly) no longer a factor. Slower but less dangerous imho.
Less snow, and you can spot (most) obstacles.
Harder snow (frozen, or earlier in the morning) is much easier - on flat ground. Ascending/descending on hardened snow : snow spikes are required !

I would imagine snow shoes would change everything, but I never tried those.

Distance wise:
I usually average about 18.6 km/day (GPS average over many years) on multiple day hikes on marked cross-country paths.
This is not representative of what a fit healthy hiker could do, obviously. I am overweight, unfit and have a quirk level limp due to a bad ankle, so don't use those number for anything except anecdotal data.

During this autumn 10 days cross-country hike in Northern Finland in October :
In 10-15 cm established snow, I averaged just under 9 km/day.
On the 1 day it was heavily snowing, I only walked less than 3 km, enough to reach a hard shelter, as I wasn't liking the idea of my tent under heavy snowfall. The lack of visibility was bad, much worse than fog or heavy rain, and in retrospect I would have been wiser to stay in place. An amazing experience, that said. Dangerous and tiring, but exhilarating.
On the following days where I had to walk into deeper, fresher snow, I dropped to slighty over 7 km/day, and it was rather more tiring than usual.

[Curmudgeon]

Originally Posted by Stormcrow

GURPS Campaign, p. 351. "Very bad" terrain includes deep snow and imposes a 20% limit to ideal daily mileage. The "snow" weather condition halves speed when ankle-length or quarters it or worse in deeper snow.

This seems to be double-dipping. I notice that in the third edition Basic Set, there was no "snow" weather condition, though "very bad" terrain still included deep snow.

Is deep snow supposed to be terrain or weather? Or is something else going on here?

P.S.: No need to talk about whether the travel rules are realistic. I've seen the other threads.

The two effects measure different things. The 0.2 factor determines the actual maximum distance you can travel. The ankle-deep and deeper penalties determine how long it takes you to cover that first distance.

Worked example:
ST 12 [20] (p. 14)
HT 14 [40] (p.15)
DX 12 [40] (p.15)
Increased Speed +.5 [10] (p. 17)
Increased Move +2 [10] (p. 17)
Enhanced Move (Ground x 1.5 [10] (p. 52)
Character is wearing a 30 lb. pack.
BL for ST 12 is 29 lb. Character’s encumbrance is more than BL (29 lb.) but less than 2 x BL (58 lb.), so Encumbrance is Light (1) and Move = Basic Move x 0.8 (p. 17).
Character has been wounded to 4 HP left. 4 < 14/3 = 4.7, so Move is halved (rounding up) (p. 419).
Character is also at 3 FP left. 3 < 12/3 = 4, so move is halved (rounding up) (p. 426).
Character is alone and does not have Hiking skill.

Thus:
Speed = (14 [HT] + 12 [ST])/4 + 0.5 [Increased Speed] = 26/4 + 0.5 = 6.5 + 0.5 =7.0
Move = 7 [Speed, less fractions] + 2 [Increased Move] = 9
Current Move = 9 x 0.8 (Encumbrance) x 0.5 (Injury) x 0.5 (Exhaustion) (round up) [note: FAQ for GURPS does not address whether or not Injury and Exhaustion penalties stack] = 7.2/4 (round up) = 1.8 (round up) = 2.

Ideal daily mileage = 10 x 2 (Move) x 1.5 (Enhanced Move) + 20% (no leadership roll required; default roll of (14 - 5) = 9-, rolled an 8 for success) = 30 + 6 = 36 miles.
Actual daily mileage = 36 miles (ideal daily mileage) x 0.2 (terrain modifier for deep snow) = 7.2 miles.

7.2 miles is as far as the character can get in one day in deep snow. How long does it take him to get there?
Ankle deep snow halves speed.
Anything deeper quarters speed.
[Anything less than ankle deep uses the penalty for the underlying terrain.]

In ankle deep snow, Move = 2 [Move]/2 = 1.
7.2 (actual daily mileage)/2 (2 x Move) [Time in hours = Distance in miles)/2*Move (in yards/sec.) derived from converting miles to yards and hours to seconds] = 3.6 hours = 3 hours 36 minutes.

In deeper snow, Move = 2 [Move]/4 = 0.5 [While it would be rounded up to 1 for Tactical Combat, I would retain the 0.5 for long-term, long distance travel).
Time to cover 7.2 miles = 7.2 hours = 7 hours 12 minutes

I would say that the worst snow is deep (cotch level or higher with an icy crust. It will just support you until you put your weight on it and then you drop through. If you don't back out to shallower snow, you're in for a long slow slog. It took me a bit over fifteen minutes to cover about 200 yards under those conditions(no snowshoes).

Snowshoes are tiring to wear as you need to take a wider, swinging step as well as a higher one. Snowshoes work best when the snow has some give to it but not too much (i.e. a bit less than knee-height give). Snowshoes are pretty much useless on compacted snow. They're not used in the High Arctic where the snow is deep but effectively like concrete. My experience is with prairie-style snowshoes (i.e., the traditional long snowshoe with a tail). Bearpaw snowshoes are almost tailless and much shorter. They're principally used in forested areas where they're more maneuverable than the prairie-style. They give good support as the snow isn't usually quite as deep. [I'm basing that on my sister's observations as a user.] I'd say you can ignore the snow penalty and treat the terrain as if the snow were equivalent ground when wearing snowshoes.

[Stormcrow]

I don't think that's how it works. Both terrain and weather allege to modify daily travel. Modifying your speed modifies your daily travel — if you can cut the time it takes to travel the maximum distance in half, you've just doubled the maximum distance.

Your example would be easier to follow without all the other modifiers.

Suppose we have the following character:

ST 10, DX 10, IQ 10, HT 10
Basic Speed 5, Basic Move 5
No encumbrance
Assume all Hiking rolls are failed.

What is the daily mileage of the character in the following situations? Assume "deep snow" weather always divides by 4.

Cross-country light forest in good weather: 50 miles
Cross-country light forest in deep snow: ?
Cross-country mountains in good weather: 10 miles
Cross-country mountains in deep snow: ?
Light forest road in deep snow: ?
Mountain road in deep snow: ?