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D System in Real Life

By Lou

Backcountry snowboarder Joel Levenberg recently sent this question (edited version below) about the D System. Working with this is a good illustration of how the D System functions, thanks Joel!

Taylor Glacier, Rocky Mountain National Park.

Taylor Glacier with complete glisse descent route marked. D System II D19 R3

“Lou, I’m curious about your opinion of what D rating would be assigned to Taylor Glacier in Rocky Mountain National Park. I snowboarded it many moons ago and did some slope measurements with a slope meter on the headwall that were beyond 60 degrees.

After the first two turns, the slope dropped down to mid to lower 50s and held that for about 400 vertical feet. There were cliffs to negotiate the entire way down. I’m including a pic a friend took recently after climbing it and a pic I took after my descent with my route painted on. Are you familiar with the route and if so what do you think? I’m proposing a II D19 R3. I’m just curious as to what your opinion is.”

Top section of Taylor Glacier, showing 60 degree crux section.

Joel, thanks for an excellent example of the D System in real life. Taylor illustrates the importance of the D Scale crux rating as part of the D System, modified by considering the length of the crux and other factors. The length of the route is rated by the roman numerals, and the “R” rating indicates the risk/danger. I’d say the grade II for length is close enough, and your R3 is reasonable as a danger rating. An R4 route would probably have items such as more objective hazards, longer steeps, or require skiing within inches of cliff edges. If the crux is usually as steep as you measured it, that places it in the D 18 or above range. Since the crux is so short I’d be conservative in the rating (a shorter crux is easier than a longer one), but if the difficult part of the route is exacerbated by terrain features you have to work around or over, then that would bump it up. Thus, I’d think saying it’s a D19 would be fine, though it could be a D18 due to how short the crux is. Subsequent descents will gradually refine the rating, as in rock climbing ratings.

Indeed, this shows how the D Scale of the D System works in similar fashion to rating a rock climbing route using the YDS system (e.g., 5.11, 5.12, etc.), since you rated a route D 19 based on the crux.

More, this example illustrates how difficult it is for any rating system to completely reflect the nature of a route. In the case of the D System, a D19 route requires skill with terrain in the realm of 60 degrees steep. BUT, there is a big difference between a Grade II ski route and a Grade V. Likewise between an R3 ski route and an R4. While one might have the technical skill to ski or snowboard a D19 crux, can they handle that type of terrain if it’s sustained for hundreds or even thousands of feet, as in the case of Mount Robson? What if they’ve been climbing for 12 hours before starting the descent? And what if the hazards of the route are causing extreme mental stress (otherwise known as fear?). Since the D System has a length and danger rating it addresses these concerns, but deciding whether to do a route or not will always require more than simply knowing a rating. As is the case with rock climbing. Thus, it’s important to include the length and danger rating along with the D Scale rating.

A while ago someone mentioned we should include the length of the crux in the D System rating. We felt that was getting too far over on the narrative side of things for a tight rating system. In other words, when does a rating become a guidebook description? Any rating system requires support from things like other people’s experience and guidebook descriptions. D System is intended to be tight and brief.

(Note, Taylor Glacier can be skied or snowboarded from lower down for a more moderate descent, and is frequently done that way. More, various starts are obvious in the photo and these could require different D Scale ratings if it’s common to pick between them.)

D System described here.

Posted by Lou on August 28, 2006 | Filed Under Trip Reports

Comments

18 Responses to “D System in Real Life”

BrianStory August 28th, 2006 9:30 am

I skied the right arm (curves behind cliffs in upper photo) of Taylor Glacier in March 2006 from above the cornice and found it to be more like 55 deg. – steep but not outrageous. And the angle dropped off 10 50 deg. after a few turns. Winter snowpack must have produced mellower slope angles for me? I’d suggest III D15/16 R3. Other than the exciting cornice entrance, I didn’t find anything much steeper than “cruxes” on N. face on N. Maroon Peak (IV D15 R4). There are at least two other superb ski lines in this cirque.
podenbeck August 28th, 2006 11:26 am

What if the D system had (a-d) or plus minus ratings as well much like the YDS. This would solve the length of a difficult section. Say a 60 degree section only lasted 20 yds that might be a D19- and another line was 60 degrees for 1/2 mile D19+. This might tighten the system up. I think that the less numbers the better.
Lou August 28th, 2006 12:12 pm

Hi, yeah, that’s one way of looking at it, but really, that’s 6 of one half dozen of the other, and we felt the numbers were cleaner. The divisions are the same. D16 is D15+

Remember that slope angle is only part of this. The rating is for how technically difficult it is to ski or snowboard. That includes how narrow the couloir is, how steep, how hard it is to do any required traverses, and more. Again, it’s like rock climbing. There is no one or two things that makes a route 5.11, ditto for D18.
Rune Kvist August 29th, 2006 12:32 am

Are you familiar with the adoption of a new rating system for ski-mountaineering in Europe – adopted from the american rockclimbing rating? (- i.e. divided into 5 classes each divided into three subclasse & the fifth grade ‘open’)

It strikes me as a very similar in approach – check the link (in french):
http://www.ffme.fr/ski-alpinisme/cotation/echelle-volo.htm

It’s still in its early stages and there’s quite a bit of disagreement (esp. in france) on finetuning the rating concerning the fifth degree (notably between chx and ecrins/volopress group)
Lou August 29th, 2006 5:31 am

Brian, it appears we would indeed rate several different descent routes for Taylor Glacier, and that you and Joel did two different ones? If so, how about we call one the headwall to looker’s left and one looker’s right?

The short cruxes definitely would cause the route to rate a bit lower on the D Scale.

I’m also thinking that when we add the Taylor looker’s left headwall to the D System examples, it would be better to rate it II or III, D18 R3.

Since the looker’s right has such a short crux, let’s go with D15 on that for now. The examples tell the story, remember that this is a linear rating scale and each route should fit in the scale in relation to the difficulty of other routes. Just like rock climbing rating. BUT, remember that the routes in the examples list are all subject to revision as to rating, I’d say many of them could go up or down a notch or two as we refine this. Ditto for the D Scale verbal descriptions, some of which might still have too much emphasis on slope angle.

Rune, I’m familiar with the Volo system you’re speaking of, and we give a lengthy opinion of it at the end of the D System page.
D System
Rune Kvist August 29th, 2006 6:28 am

Ups! Missed that ;-)
Alan Angelopulos November 17th, 2008 8:19 am

I recently viewed your ski descent ratings on this website. I noticed Mt Torreys has two descents rated: Dead Dog and the Tuning Fork. I’m wondering if the north face (you can see from I-70) has a rating.

We skied it back in June of ‘93. We skied the line that looks like a giant funnel for the first 700 feet or so, then spills into another colouir on skier’s left.
While skiing this line in 93 a guy from the summit followed us in- and ended up falling the first pitch and over the cliff at the bottom. Our epic descent turned into a rescue. He survived, and we were able to get him out by the afternoon. He fractured his hip and broke some bones in his face.

Anyway, I skied the Tuning Fork this year, and while on the summit I looked down the north face and wondered, “how would Lou rate this?”

Let me know if you have any thoughts on this,
Thanks- Alan
Lou November 17th, 2008 8:27 am

Alan, I’ve not skied that route (only so many times I can make that road trip…). How about you try rating it? If someone could fall down it and get hurt or killed then then it’s R3 or R4, in terms of length grade III, but the difficulty? Somewhere around D 11 or above?

The route you speak of is also called “Gunner’s” because it used to be fired on as a test slope by the avalanche howitzer crew, or so I’ve heard.
Alan Angelopulos November 17th, 2008 10:35 am

I would say D12 or D13 because it chokes down very narrow as it turns left into the other colouir. We had to straight line this section.
Anybody else have a rating for this line?
Rob A (in NJ) December 10th, 2008 9:58 pm

hey guys,
I like your system and I am wondering how it applies out here in the east.

I’ve made two pages on summitpost.org of two ski routes that I did this past winter. I gave them a D-System rating in hopes of getting some feed back from others on how the D-System works out here. Here are the link to the two route I’ve posted. I was wondering what you guys think about the ratings I gave the routes.

The Chute @ Tuckerman’s Ravine

Bennies Brook Slide, Lower Wolf Jaw, Adirondacks, NY

Thanks guys,

Have a good winter.

Rob
Lou December 11th, 2008 7:15 am

Rob, how about linking back to the D-System page somehow from the SummitPost route page? I’d appreciate that, and it would probably help users of the route description.
Pat February 16th, 2009 9:46 pm

Lou,
To help fill out the D-System examples, Steve Romeo has been doing a three-part series on the Hossack-MacGowan Couloir.

Might want to link ‘em.

I think it’s a useful system. I always try to compare what I’ve done to what I want to do. Helps me figure out how close (or far!) I am.
Stan Wagon June 24th, 2009 7:53 am

I can’t agree with the D7 on Democrat N Face. I remember that Lou called this “extreme” in his 14er book. I skied it yesterday for the third time. The face is wide and there is some route latitude. But there is a nasty choke at the bottom of the usual exit (can be avoided by going far left, but few do that). And it is quite steep at the very top and though it eases, it is still pretty steep. The “feel” of all this to me is much more gripping than other routes around here in the D7-8 range. I say D9.

Yesterday we did it, avoided the very bottom choke, which was not skiable, by traversing right so as to climb back to the Democrat-Cameron saddle, which makes the round trip much more compact than the other ways this is commonly done (5 hrs r.t.)
Lou June 24th, 2009 8:11 am

Hi Stan, thanks so much for the feedback. As with rock climbing, the D System works by consensus and opinion, so I’ll take a look at the rating.

And, like rock climbing, D System does allow for some sand bagging (grin).
Stan Wagon June 25th, 2009 10:06 am

Re the Torreys post from last fall:

Locals call that face on Torreys (the one on the N Face well east of the Tuning Forks) the Little Diamond.

I have also heard “Emperor Face”.

It gets skied quite a bit but I have not done it and so I cannot comment on the rating. But one accident was mentioned above and I recall another from a few years ago (different I think) where the fellow was very badly hurt and died after some months in a hospital . So this is clearly a line with some serious potential for mishap.

My list including D-ratings of many Summit County and nearby routes is at the bottom of the page.
Lou June 26th, 2009 1:56 pm

Locals? I didn’t know anyone lived in Bakerville.
Tony July 1st, 2009 8:06 pm

Were the rating examples rated by the skiers who skied them or based on your estimates? Upon submitting this rating system, I suggest limiting the list
Lou July 1st, 2009 8:21 pm

Hi Tony, it’s some of both.

What do you mean by “submitting this rating system” ?