Sunday's event on Burbage Moor reminded me of this perennial discussion regarding the variations in runnability on moor land and how we seem to tolerate this indeterminacy out in open but not when beneath the trees. I recall a discussion of the issue here, prompted by BOC on Brown Clee Hill http://forum.nopesport.com/viewtopic.php?f=1&t=14864&p=169754&hilit=rough+open#p169754.
ISOM17 describes rough open as the equivalent of runnable forest, runnability 80-100%. I assume it is envisaged that 'undergrowth' screens 407 and 409 be used to indicate areas where the runnability falls below that mark. However, this typically seems to be used where the obstacle is an invasive species such as bracken and not for deep heather or deep, grassy tussocks.
I can understand the reluctance. Time is one factor. Another is legibility. Undergrowth screens negatively impact legibility of the contour detail, though this applies to both open and forested land, which raises the question of why they more likely to be omitted on open land than in the forest. On the other hand, information on runnability is vital in route selection and its absence introduces a degree of luck/fairness/local knowledge. This is something a good map should seek to minimise.
Are there examples of maps where deep heather has been mapped? Off the top of my head, I can think of the NW corner of the Glen Feardar West map on S6D 2017. Any others since then?
up-date:
Let me clarify my purpose in starting this discussion.
I think it is an open secret that the runnability of rough open on orienteering maps can vary from very fast to very slow and that it is routinely less well-mapped in this respect than forest.
I am writing an article about this issue. The article is discursive rather than a complaint or a call for action. I opened the thread to invite responses to that opening statement. Perhaps it is wrong, for example, and there is as much indeterminacy in forest mapping as there is in rough open. Perhaps people believe it is something we must tolerate, or conversely that it should be mapped, given availability of base materials. Examples of terrain where it was a problem and proved to be unfair, or where it was well-mapped would be useful.
Thanks.
Rough Open Runnability
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Rough Open Runnability
Last edited by Parkino on Fri Mar 03, 2023 11:04 am, edited 2 times in total.
- Parkino
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Re: Rough Open Runnability
For Heather that you can run through without much difficulty, I'd think about mapping it with 404.001 Rough Open with Scattered bushes.
For more hard going stuff, then the vegetation screen or even use of 406/407 might be appropriate, depending on height.
Tussocks is a more difficult issue. If it's an extensive area, then use of 113 Broken ground or 114 very broken ground might be appropriate.
But I've yet to see any maps that do this.
For more hard going stuff, then the vegetation screen or even use of 406/407 might be appropriate, depending on height.
Tussocks is a more difficult issue. If it's an extensive area, then use of 113 Broken ground or 114 very broken ground might be appropriate.
But I've yet to see any maps that do this.
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Re: Rough Open Runnability
I suspect time/difficulty of mapping is a consideration - bracken is relatively easy to see and survey but heather can vary significantly and extent of deep areas harder to spot from aerial photos or on the ground.
The other problem with bracken (and brambles to a lesser extent) is that its seasonal - Burbage is mapped for the worst case summer runability and for much of the year its often more runnable than the heather which makes route choice even more unfair.
Some notes in the final details might have helped as would courses planned to avoid the worst of the heather.
The other problem with bracken (and brambles to a lesser extent) is that its seasonal - Burbage is mapped for the worst case summer runability and for much of the year its often more runnable than the heather which makes route choice even more unfair.
Some notes in the final details might have helped as would courses planned to avoid the worst of the heather.
To oblivion and beyond....
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Re: Rough Open Runnability
I'd have thought heather was easier to map than bracken.
It doesn't move/die off so much, nor spread so quickly.
I wouldn't expect a mapper to cover every single square metre on the map (although I do try), but having a good idea of generalised vegetation runnability at all points is part of the job.
The planner should be looking at this too.
Didn't run the event (still broken), so shouldn't really comment on whether this happened at burbage, but I have done other events where planners clearly haven't considered runnability. Particularly on the longer courses.
And whilst orienteering should be a physical challenge, I do sometimes get the feeling some planners throw in legs through deep heather or similar to make the courses "feel" hard.
Maybe I'm just being cynical again.
It doesn't move/die off so much, nor spread so quickly.
I wouldn't expect a mapper to cover every single square metre on the map (although I do try), but having a good idea of generalised vegetation runnability at all points is part of the job.
The planner should be looking at this too.
Didn't run the event (still broken), so shouldn't really comment on whether this happened at burbage, but I have done other events where planners clearly haven't considered runnability. Particularly on the longer courses.
And whilst orienteering should be a physical challenge, I do sometimes get the feeling some planners throw in legs through deep heather or similar to make the courses "feel" hard.
Maybe I'm just being cynical again.
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Re: Rough Open Runnability
buzz wrote:I suspect time/difficulty of mapping is a consideration - bracken is relatively easy to see and survey but heather can vary significantly and extent of deep areas harder to spot from aerial photos or on the ground.
Oh, I'm sure time is the principal factor and there's a time/value calculation to made. I was able to identify the deep heather on East Moor (behind Chatsworth) using LIDAR and it has been represented on the map as 407, further down the hill the slough of deep tussocks are sufficiently wet to be mapped as marsh.
On Burbage the bracken was often faster than the adjacent terrain, especially on the west side of the valley, but it was accurately mapped and useful for navigation. There was no way to avoid the deep heather in the NE.
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Re: Rough Open Runnability
I'd have thought heather was easier to map than bracken.
You can usually identify bracken on the moors from aerial photos and if you visit it's easy to determine the extent it will impede progress—without having to test it out. I'd guess that's why it gets mapped when heather does not.
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Re: Rough Open Runnability
But the point is that one is mapping the runnability not the species! So in the case of Burbage, the bracken should not have been mapped for a Febraury event as it is flat to the ground... if mapped, it should not have been as "slow" but rather as "fast".
The heather areas were defintely slow run (for 21s, walk for most!) but it didn't matter much that it wasn't mapped as there was no route choice and no way of avaoiding it. Why the planner sent almost all courses through it rather than using the excellent (in February) western area, I don't know. I think only 4 courses went west... I wish I'd done course 4.
If you put course 8 on route gadget and tick the box for all 13 routes added, you'll see how little route choice there was.... just a long line of old folk trudging/crawling through the heather.
(PS no one could cover every square metre of Burbage and survive!)
The heather areas were defintely slow run (for 21s, walk for most!) but it didn't matter much that it wasn't mapped as there was no route choice and no way of avaoiding it. Why the planner sent almost all courses through it rather than using the excellent (in February) western area, I don't know. I think only 4 courses went west... I wish I'd done course 4.
If you put course 8 on route gadget and tick the box for all 13 routes added, you'll see how little route choice there was.... just a long line of old folk trudging/crawling through the heather.
(PS no one could cover every square metre of Burbage and survive!)
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Re: Rough Open Runnability
Parkino wrote:I'd have thought heather was easier to map than bracken.
You can usually identify bracken on the moors from aerial photos and if you visit it's easy to determine the extent it will impede progress—without having to test it out. I'd guess that's why it gets mapped when heather does not.
Is this not heather seen on the google aerial image?
https://www.google.com/maps/@53.3392972 ... a=!3m1!1e3
Now it might not be strictly accurate, but you can get a good estimate of the extent and then estimate runnability on the ground survey?
But my terrain mapping experience is limited.
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Re: Rough Open Runnability
Now it might not be strictly accurate, but you can get a good estimate of the extent and then estimate runnability on the ground survey?
Yes, it is. You can identify the extend of heather cover easily enough, but not its depth and you'd really have to wade through it to determine its runnability, which is time-consuming and largely thankless. Bracken on the other hand can be assessed at distance, in my experience.
But does anyone have some good examples of rough open runnability mapping? I fear they tend to be too busy.
It's one of those things.
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Re: Rough Open Runnability
Parkino wrote:Yes, it is. You can identify the extend of heather cover easily enough, but not its depth and you'd really have to wade through it to determine its runnability, which is time-consuming and largely thankless. Bracken on the other hand can be assessed at distance, in my experience.
Sorry, not seeing the distinction.
You have to assess *all* vegetation on the ground.
You can't just rely on an estimate from aerial photography.
As I said earlier, I'd never expect anyone to cover every bit of ground, but you should be able to do rough generalised efforts.
Rather than leaving if off the map altogether?
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Re: Rough Open Runnability
rf_fozzy wrote:Parkino wrote:Yes, it is. You can identify the extend of heather cover easily enough, but not its depth and you'd really have to wade through it to determine its runnability, which is time-consuming and largely thankless. Bracken on the other hand can be assessed at distance, in my experience.
Sorry, not seeing the distinction.
You have to assess *all* vegetation on the ground.
You can't just rely on an estimate from aerial photography.
As I said earlier, I'd never expect anyone to cover every bit of ground, but you should be able to do rough generalised efforts.
Rather than leaving if off the map altogether?
The distinction is that bracken can reliably be assessed when standing at its the edge while heather cannot because the depth of heather tends to vary: you should only be mapping deep heather, where running pace is reduced to below 80% for an 'average elite runner' (which equates to something closer to 60% for the rest of us).
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Re: Rough Open Runnability
But the point is that one is mapping the runnability not the species! So in the case of Burbage, the bracken should not have been mapped for a Febraury event as it is flat to the ground... if mapped, it should not have been as "slow" but rather as "fast".
It was the reversal in runnability (from slow to fast) that was intriguing and highlighted the tendency to map bracken on rough open moorland but not heather, even though deep heather can impede progress as much as certainly below the designation of 'runnable forest' (see ISOM17-2 runnability chart).
Again I suppose at the height of the season areas of bracken become difficult to run for all athletes so there's something unequivocal about that, unequivocal but seasonal!
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Re: Rough Open Runnability
Parkino wrote:
The distinction is that bracken can reliably be assessed when standing at its the edge while heather cannot because the depth of heather tends to vary: you should only be mapping deep heather, where running pace is reduced to below 80% for an 'average elite runner' (which equates to something closer to 60% for the rest of us).
Nope, still not seeing the distinction.
I'd still be assessing it.
And I'd be assessing it the same as I did vegetation in woodland using walk undergrowth (60-80% of full speed), slow run undergrowth (20-60%) and fight (<20%) as necessary.
Obviously I'd generalise.
Bracken or heather I'd be following the same process - extents from Aerial photography if available, then ground based surveys.
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Re: Rough Open Runnability
Let me clarify my purpose in starting this discussion.
I think it is an open secret that the runnability of rough open on orienteering maps can vary from very fast to very slow and that it is routinely less well-mapped in this respect than forest.
I am writing an article about this issue. The article is discursive rather than a complaint or a call for action. I opened the thread to invite responses to that opening statement. Perhaps it is wrong, for example, and there is as much indeterminacy in forest mapping as there is in rough open. Perhaps people believe it is something we must tolerate, or conversely that it should be mapped, given availability of base materials. Examples of terrain where it was a problem and proved to be unfair, or where it was well-mapped would be useful.
One response has been 'I would map it all,' another noted the time constraints.
I attach the runnability chart from the specifications:
I think it is an open secret that the runnability of rough open on orienteering maps can vary from very fast to very slow and that it is routinely less well-mapped in this respect than forest.
I am writing an article about this issue. The article is discursive rather than a complaint or a call for action. I opened the thread to invite responses to that opening statement. Perhaps it is wrong, for example, and there is as much indeterminacy in forest mapping as there is in rough open. Perhaps people believe it is something we must tolerate, or conversely that it should be mapped, given availability of base materials. Examples of terrain where it was a problem and proved to be unfair, or where it was well-mapped would be useful.
One response has been 'I would map it all,' another noted the time constraints.
I attach the runnability chart from the specifications:
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Re: Rough Open Runnability
Nope, still not seeing the distinction.
The distinction is in what you need to do in order achieve a reliable assessment of the runnability: you need more information on depth of heather than you do on bracken (when in season). This distinction is not speculative or theoretical, but derived from experience.
But the thread was about why runnability of rough open is not mapped as thoroughly as forest.
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