Normandy: Immobilisations

[flamingknives]

I rather suspect that the earlier test was Russian vs. German on wet ground rather than checking for bogging on dry ground.

Unfortunately that was on an old computer and I can't be bothered

a) Finding it and all the requisite cables

Starting it up

c) finding the scenario and checking.

[undead reindeer cavalry]

But again, it's an apples to oranges comparison. You are comparing a statistic for a type of immobilization that CM doesn't actually bother to simulate. Specifically, in CM an immobilization that would last long enough to be noted in a unit status report isn't explicitly simulated. That means in CM there is no difference between an immobilization that took 1 hour to extract or (like in that Tiger Battalion report) 3 days. What you're doing is treating all immobilizations you see in CM as if they are all of the latter type and not even one of them of the former type. That simply doesn't work.

that is not what i am doing. i have one number that is historical number for type B. i have another number that is CM test result for type A. thus i have difference between two different types in given numbers, A:B. i am not suggeting that A should be B.

yes, i don't factor between 1 hour or 3 day extractions, like i don't factor in historical losses that would not show as CM immobilizations (damages that don't result in immobilization or "gun damage").

Immobilizations, however, do have an impact on the Campaign. You get most of your immobilized vehicles back for future battles.

cool

You are also, once again, forgetting that you are mixing road marches with off road use. You can not compare the average for an entire large period of time, which is disproportionally road marching, with a very small slice of non-road marching combat time. It is statistically impossible to take a large abstract set of data and compare it to a specific set when one of the most fundamental variables is completely skewed.

that is what Operational Research guys actually do. collect a huge dataset, generate numbers from it and then start looking for these fundamental variables by comparing details in differences.

at the moment, according to Vulture's test, we have data which would indicate that "combat conditions" is not a variable that matters (because no losses on paved roads). it would also seem that "random mechanical breakdowns" is not a variable that matters (because no losses on paved roads).

thus the variables are probably down to vehicles (differences between T-34 variants), vehicle crews (differences in quality of), HQs (quality of & wether in command or not), terrain tile types (difference between) and terrain and scenario settings (dry vs other, time of day, date etc...).

currently, accroding to Vulture's test, the differences in latter result in higher than the earlier 1:400 ratio. common sense would hint that most likely the differences come from terrain tile types, ground conditions, vehicle crew quality and T-34 variants. finding the weight of these variables should be relatively easy, considering the extreme difference in results.

To illustrate my point (since apparently you still don't understand it), here is what you could do to better figure out if those higher level numbers are proportionally similar to what CM simulates. Take a bunch of tanks and put them on roads in weather conditions similar to the report you're comparing to. Drive those tanks on roads in 2km increments. Do that a couple hundred times and then count how many vehicles became immobilized. Then take that number and divide by an arbitrary number like 5 or 10 to represent the number that could be fixed or unstuck within 24 hours.

i would naturally do my own tests if CMBB worked fully on my Vista computers. :\

Then, and only then, will you have a set of CM game data that is more-or-less approximating those higher level numbers. Still, it's a very dodgy comparison because we don't know how much of the higher level numbers had offroad combat included, nor do we know if they ran into some sort of local terrain that was better/worse than average. However, the resulting data from CM tests as I laid out would be radically more accurate than the small sample you're using from offroad driving.

of course. i could also collect all sort of data for all sort of conditions. but as long as there's stuff like 1:400 difference i don't see much need for. i have read enough low level stuff to know that the figure between road:cross country movement isn't 1:400+.

luckily Vulture did tests and we now know better where those high immobilization numbers come from; or rather we know that they don't apply to road movement on dry ground conditions.

They had some recovery and repair capabilities, although obviously not very good due to a host of factors. But their record keeping and honesty of numbers were also quite poor. So I'm not sure what early war Soviet stuff has to so with this discussion.

yeah, perhaps they just lied.

though if it's worth it, i could waste time by creating number from e.g. Ardennes that are cross country in real crappy terrain conditions with orders to abandon vehicles that become bogged or suffer mechanical problems. the problem for motivating myself to do that is that i am 99% certain the numbers won't be 1:400. i wouldn't be surprised if it was more like 2:1 in favour of cross country movement.

though, perhaps Germans lied as well.

what all this has to do with the discussion is that in those conditions many of those "1 hour extraction" cases were very likely to lead to marks in daily losses statistics.

[undead reindeer cavalry]

searched for other T-34 results. T-34 on damp ground, open terrain, 2-2.5% immobs per km. that potential wet ground test gives 2-3.3% immobs per km.

[Redwolf]

I see both test 1 and 3.

I mean why in the world did that test got reduced to these "safe" conditions?

[Battlefront.com]

dieseltaylor ,

Bocage - I am rather hurt that you see me as a lightweight in the bocage!

Well, you've established a rather strong position which I've never encountered in about 25 years of actively studying WW2. Therefore, I don't think you should be "hurt" that I asked you for sources.

If certain information is repeated often enough gets tobe taken as fact.

Sometimes information is repeated because it is fact

However relatively few people have actually described the "bocage" that they drove through.

Not true at all. I've seen very detailed reports and descriptions.

In CMAK the bocage/tall hedge is driven through with nary a stop - I think 15 seconds is the fastest. And curiously this probably is pretty much what the show for the Press and Generals demonstrated. The faster the tank the faster it goes through.

I don't think the latter part is accurate and I don't remember CMAK being relevant in any case. But whatever, CMBO's treatment of going through hedges was extremely abstract.

However to extrapolate that Show to 6ft banks with trees and bushes that have been growing there for several hundred years is lunacy. One might easily argue that rather like buildings bocage is a hugely variable and someone who is used to what passes for hedges and fences in the US may think a modest bocage is the be all and end all on the subject.

Well, that's just it. Bocage *is* extremely varied, similar to buildings. Not every building is built out of reinforced concrete, not every linear foot of every hedgerow has 6' banks with 4' diameter trees. Breaching has to be done where it is practical to get the tank into position, and a 6' berm of earth is not one of those places. Easily simulated in CM: Normandy so there definitely will be hedgerows which can't be breached.

At one stage I read a unit history - a US unit who was most instructive on the short size of the fields which meant repeated ramming was required and this was very bad for the tank. The tracks simply could not provide enough traction to force a way through. This was particularly true in damp conditions and also where a field was sloped to the side. By my reckoning he was on a medium bocage route.

Sure, it didn't always work. No question about it. But to conclude that was the norm, and therefore that the cutters were an imaginative PR invention, does not hold water. On topic to this thread that would be like reading about a tank that got bogged and concluded that all tanks got bogged when going into that particular type of terrain. Real life tends to be far more complex.

If you want to carry this conversation further please start up a unique thread for it because it's unproductive to have an off-topic side conversation going in this thread.

Steve

[Battlefront.com]

Back on topic.

Starting with Redwolf's question first:

I mean why in the world did that test got reduced to these "safe" conditions?

Because I suggested we start looking at apples to apples instead of apples to oranges. The statistics that URC brought into this discussion (the only statistics, in fact) were about road marches. Therefore, comparing road march statistics for hundreds of tanks to a small off-road test under unknown ground conditions is a very bad idea. And the results proved why it was because URC was originally showing a HUGE gap between the higher level road march numbers and the small off road sample with unknown conditions, but once things were made more comparable the gap disappeared. Obviously this doesn't surprise me at all

Now, I personally would have done the tests on dirt roads because that's the better condition to test because its a better match to the real world data from URC with the game. But overall we're now comparing one type of apples to another type of apples, instead of comparing apples to bananas... so while not perfect, we've now got a far better frame for the discussion than we had. If someone does dirt road tests we'll even be closer to a correct apples to apples comparison.

undead reindeer cavalry

it's a bit curious that in the linked thread someone's test gave 10% Tiger I losses for 4 km on open dry ground. i wonder if this stuff was fixed for some CMBB version after those tests.

This is why using a single player's "data" from 4 years ago without careful notations of the conditions isn't the best basis for a new discussion. Especially since the guy who did the original test is here in this thread and even he doesn't remember what the exact conditions were

so yeah, ignoring other things, 29th TC data set would imply a single immobilization for your test.

Good. We're finally getting somewhere

indeed. i find those linked earlier test results a bit puzzling in the light of your test. either something has been changed in CMBB, there's some setting detail that makes a huge difference or immobilization & bogging do not happen on road tiles (which would be very odd if it represent mechanical breakdowns as written earlier).

Immobilization/bogging is extremely rough because there is no good data to go from, plus the CMx1 terrain was quite primitive. So as far as Charles and I are concerned Bogging itself was just getting stuck, while Immobilization was getting stuck in a way that wasn't immediately recoverable. The reason for that could be purely based on terrain conditions, purely because of breaking something while trying to extract, or a combination. CMx1 nor CMx2 simulate non-movement and non-combat related breakdowns. It's something we don't feel we can simulate with even moderate amount of accuracy because of the massive variability. I'd take the a generally unreliable vehicle right out of a motor pool overhaul than the most reliable that has been out in combat conditions for a couple of weeks. Not that we have the sort of statistically relevant and complete data samples to even establish a baseline for each and every vehicle, because we don't.

that is not what i am doing. i have one number that is historical number for type B. i have another number that is CM test result for type A. thus i have difference between two different types in given numbers, A:B. i am not suggeting that A should be B.

No, but you're saying that B can be derived from A and I've made the case that you can not. You'd be better off accepting that and spending your energies looking at more relevant data now that someone else has taken the time to provide it. That data itself isn't perfect, but it is far more relevant than the sample you were using.

that is what Operational Research guys actually do. collect a huge dataset, generate numbers from it and then start looking for these fundamental variables by comparing details in differences.

So you REALLY want me to believe that the Soviets had guys walking around bothering field commanders in hot pursuit of the Germans "how many vehicles did you get stuck yesterday for 2 minutes? OK, how many for 5 minutes?". I highly doubt it. Instead what almost for sure happened is the commanders provided a form to higher command with the number of vehicles they had running at the time of the report. Since that really is all that is relevant, why on Earth would they document micro bogging that had already been cleared up? There's absolutely no military use for that data at the time and, arguably, no use for it at all. Unfortunately, that's the type of data we would love to have. But we don't have a war to fight and a country to liberate, so our motivations for statistics are a bit different

at the moment, according to Vulture's test, we have data which would indicate that "combat conditions" is not a variable that matters (because no losses on paved roads).

Incorrect. Combat is generally conducted off road, so combat conditions inherently means interacting with terrain other than roads. At least to a large extent (cities excepted, for example).

it would also seem that "random mechanical breakdowns" is not a variable that matters (because no losses on paved roads).

Correct. As explained above there is no explicit simulation of mechanical breakdowns because that's definitely not something we're comfortable simulating. Far too subjective and therefore we're more likely to make the game less realistic by assigning variables to vehicles based on personal guesses rather than solid information.

thus the variables are probably down to vehicles (differences between T-34 variants), vehicle crews (differences in quality of), HQs (quality of & wether in command or not), terrain tile types (difference between) and terrain and scenario settings (dry vs other, time of day, date etc...).

Terrain type, modified, crew experience, ground pressure, and speed are the primary values I can remember off the top of my head. I don't remember if power to weight ratio counted, nor if there was any special penalty/bonus for weight of the vehicle.

currently, accroding to Vulture's test, the differences in latter result in higher than the earlier 1:400 ratio. common sense would hint that most likely the differences come from terrain tile types, ground conditions, vehicle crew quality and T-34 variants. finding the weight of these variables should be relatively easy, considering the extreme difference in results.

of course. i could also collect all sort of data for all sort of conditions. but as long as there's stuff like 1:400 difference i don't see much need for. i have read enough low level stuff to know that the figure between road:cross country movement isn't 1:400+.

I disagree. Get better data that is more relevant first, then come to some conclusions. We're not even sure there is a 1:400 ratio since the data you used to come to that conclusion isn't properly documented. Since better data can be got from the game by anybody caring to get it I don't find it even remotely productive to continue using questionable data.

luckily Vulture did tests and we now know better where those high immobilization numbers come from; or rather we know that they don't apply to road movement on dry ground conditions.

Which I think I said on Page 2 of this thread Specifically, PaulAU kept mentioning it as if it happened all the time and eventually even he admitted that it was a strawman argument.

yeah, perhaps they just lied.

You're saying that if a T-34 got stuck, the second that happened the crews got out and walked away? There was no attempt to do anything, even simple things, like fix a broken track link or have another tank give it a push? I find that hard to believe so I find your absolute statement to be a mischaracterization of reality. Reality may be that Soviet recovery and repair capabilities were extremely poor, but they weren't absolutely non-existent.

what all this has to do with the discussion is that in those conditions many of those "1 hour extraction" cases were very likely to lead to marks in daily losses statistics.

It's an illogical position to reach. If you wish to continue pursuing this I challenge you to back it up with fact. Otherwise you're holding a position which is neither supported by anything.

Steve

[stikkypixie]

I mean why in the world did that test got reduced to these "safe" conditions?

Because of the 40% bogging rate claim. I actually understands Paul's frustration, don't even get me started on 80mm Stugs...

[Battlefront.com]

Before we start down the road of underdocumented sources, URC...

searched for other T-34 results. T-34 on damp ground, open terrain, 2-2.5% immobs per km. that potential wet ground test gives 2-3.3% immobs per km.

Please cite the source and as much information surrounding this data as possible. The first piece of information I want to know is what an "immobilization" is defined as.

To restate what should be obvious...

There is no such thing as a singular definition of "immobilization". It can represent a very large number of conditions or a very small subset of that range. When doing a statistical comparison of one set of data vs. another set of data it is critical, and I mean CRITICAL, to know that the conditions are similar for both. If you don't know what the historical data represents then you have to go with the most common historical use of that.

The most common historical use of "immobilization" depends on the context. Sometimes "immobilization" is due to combat action (like a shot to the tracks or hitting an AT mine), sometimes it is used to describe a mechanical breakdown. Higher level historical data almost always concerns itself with vehicles which aren't expected to be available for combat the next day. Really good reports have "immobilized" vehicles categorized by how serious the problem is. I've read plenty of German and American reports with such notations, but generally they include all forms of broken down vehicles (i.e. including combat damage) so they aren't useful for this discussion.

And that's the key thing. Put yourself in a higher level commander's shoes. What is it you care about? You care about how many vehicles you have that can be put into action against the enemy within a given period of time, correct? So why on Earth would the commander want to be bothered with statistical trivia about vehicles which are currently running? All he cares about is if it is running now and if it isn't how long until it can be. Everything else is absolutely not of a concern for him and therefore isn't collected on a regular basis.

Good commanders have a sense of how well units have done during the day based on their progress and commander's reports. If a Tank Company Commander had a really bad time getting bogged and unstuck the commander would describe that in words. "We made slower progress than planned due to ground conditions causing a large amount of bogging. We succeeded in finding alternative routes to the objective but arrived too late to complete occupation before the onset of night". That sort of thing. Having some sort of anal retentive and scientifically sound method of regularly and consistently noting minor flux in combat strength during the day simply has no point from a military standpoint. Which is what that sort of data doesn't exist no matter how much we would like it to

Steve

[dieseltaylor]

I thought bogging and immobilisations would be relevant to tanks who rammed earthen banks in CMx2 Normandy.

It is CMAK where the Stuarts go through in 20 seconds.

I will start a new thread as requested. However for those that do not follow to the new thread these excerpts were taken by someone from Doubler, and Ambroses work. One or other has inserted a very large lie in the following:

The American troops who fought in Normandy will remember fighting in the hedgerows or bocage. Stock raising and fruit growing are the main rural activities in this part of Normandy, and the field system is characterized by a patchwork layout of irregular fields varying from narrow ribbon-like strips to squared-shapes. These range in size from 10 or 15 to a 100 acres or more. The majority however, ranged from 50 to 75 acres. Some contained orchards of apple trees, more are used for pasture, and there are occasional patches of grain.

Boundaries between the fields follow north-northeast to south-southwest and west-northwest to east-southeast axes in the Omaha region, and they could not be counted to provide a safe direction-line for keeping an axis of advance (www.army.mil.com). The hedgerows form a natural fence and vary in shapes. Some are low bushes, five to six feet high, growing from the ground level of the field and not hard to break through. Others are thick, densely matted walls of tough and briery hedge, running up to 10 feet in height and interspersed with large and small trees. Many hedge embankments are not passable for tanks. Communication between fields is usually limited to small openings at the corners. Narrow trails or sunken roads, running between parallel hedgerows give access to fields far off the regular road net (www.army.mil.com).

: )

Both authors are the kind of people who will be quoted repeatedly.

[YankeeDog]

Er... I could be wrong about this as it's been a while since I fired it up, but to the best of my recollection, there is no "Bocage" in CMAK, just "Tall Hedges." And I seem to recall BFC specifically saying that Tall Hedges in CMAK were NOT intended to represent bocage, but rather just a generic Southern European line of bushes ~ 2m in height. IIRC, there were requests to model bocage in CMAK, but BFC did not include it because there wasn't anything like bocage in the theaters CMAK is intended to represent.

AFAIK, CMBO is the only one of the three CMx1 games that modeled bocage. So any information about how quickly Stuarts traversed hedges in CMAK is completely irrelevant.

Or perhaps I'm just confabulating all this... it's happened before.

Cheers,

YD

[dieseltaylor]

I have to report bocage or not tall hedges are only passable by Allied tanks only, after a certain date in 1944.

[Combatintman]

I hate to be negative but this is horrendously emotional - the more Steve has to answer this stuff the longer you guys will have to wait for 'Normandy'.

Just out of interest - how many of you so-called 'experts' have either commanded or crewed an armoured vehicle of the 1940s in bocage terrain or at any other time for that matter? The key things to remember here are the classic Von Moltke quote about no plan ever surviving contact with the enemy and another quote about the essence of war is friction. What about the infantry model - have you ever had scenarios where blokes get lost in the game? Happens a lot in real life but I don't see any gum bumping going on about turning on or off the facility that blokes turn up at the right place at the right time most of the time in the game.

The model in all of the CM-series games that I've played is pretty ok and I don't deny that I get urinated off when I get wagons that are bogged/immobilised but I can get over it .... so long as there are power-ups.

[TheVulture]

More in-game testing for the masochistically inclined.

Test 4: t-34s on dirt roads, damp conditions (same 4km drive x 30 tanks as before). 20 runs, 0 boggings. That's 30 t-34s driving 80km each with nary a glitch between them on damp dirt roads. That sounds better than what I'd expect in real life, not that I'm an expert.

Beginning to wonder if my copy of CMBB includes bogging at all (despite knowing damn well I've had it in the past).

Test 5: 30 x t-34 on dirt roads, wet conditions, and we finally have some action. After 5 sets of runs, I have a total of 10 bogs, 5 of which give immobilisations. For one tank, that is a bog every 60 km and an immobilistaion (in game terms) every 120 km. No idea how realistic that is.

At the other extreme, lets have some hot tiger action in the same wet conditions.

test 6: 30 x tiger on dirt roads, wet conditions. 5 sets of runs again (5 x 30 tigers x 4 km). Total of 47 bogs observed. 35 of those freed themselves, 12 became immobilised. That's a bog every 12.8 km for a tiger, and an immobilisation every 50 km.

[dieseltaylor]

Just out of interest - how many of you so-called 'experts' have either commanded or crewed an armoured vehicle of the 1940s in bocage terrain or at any other time for that matter?

Experts? As far as I am aware this site is populated by wargamers/historians. Who are you suggesting is calling themselves an expert? I trust you are not referring to Steve just because he has actively read books for 25 years.

[Combatintman]

Dieseltaylor - I'm not suggesting anybody is calling themselves an expert I'm trying to get this debate off the 'I read this book which says that in x condition y happened ergo it must be in the game because it supports my soap box subject/pet peeve'. For me - bottom line is that in my experience of playing the CM series I have had vehicles bog in/get immobilised and the average seems about right. At the end of the day this thread has banged on for 19 pages with what seems to me to be the object of giving the player a button that will turn off vehicle bog-ins/immobilisation. Given that the model already employed:

a. Isn't overly intrusive.

b. Reflects the fact that this happens.

c. Seems fairly balanced.

d. Will in all likelihood be retained.

It seems pretty pointless dragging up extremely selective quotes/examples trying to prove the point.

[Redwolf]

I hate to be negative but this is horrendously emotional - the more Steve has to answer this stuff the longer you guys will have to wait for 'Normandy'.

Just out of interest - how many of you so-called 'experts' have either commanded or crewed an armoured vehicle of the 1940s in bocage terrain or at any other time for that matter? The key things to remember here are the classic Von Moltke quote about no plan ever surviving contact with the enemy and another quote about the essence of war is friction. What about the infantry model - have you ever had scenarios where blokes get lost in the game? Happens a lot in real life but I don't see any gum bumping going on about turning on or off the facility that blokes turn up at the right place at the right time most of the time in the game.

The model in all of the CM-series games that I've played is pretty ok and I don't deny that I get urinated off when I get wagons that are bogged/immobilised but I can get over it .... so long as there are power-ups.

And which games are those?

Power-ups? You have the version with god mode?

[Sgt Joch]

More in-game testing for the masochistically inclined.

Test 4: t-34s on dirt roads, damp conditions (same 4km drive x 30 tanks as before). 20 runs, 0 boggings. That's 30 t-34s driving 80km each with nary a glitch between them on damp dirt roads. That sounds better than what I'd expect in real life, not that I'm an expert.

Beginning to wonder if my copy of CMBB includes bogging at all (despite knowing damn well I've had it in the past).

Test 5: 30 x t-34 on dirt roads, wet conditions, and we finally have some action. After 5 sets of runs, I have a total of 10 bogs, 5 of which give immobilisations. For one tank, that is a bog every 60 km and an immobilistaion (in game terms) every 120 km. No idea how realistic that is.

At the other extreme, lets have some hot tiger action in the same wet conditions.

test 6: 30 x tiger on dirt roads, wet conditions. 5 sets of runs again (5 x 30 tigers x 4 km). Total of 47 bogs observed. 35 of those freed themselves, 12 became immobilised. That's a bog every 12.8 km for a tiger, and an immobilisation every 50 km.

good work on the testing. If anything, that shows that the bogging/immobilization rate in CMBB is actually more favorable than real life.

I tracked down a report in Panzertruppen, vol 2. about a unit of 14 tigers which drove from Rome to Anzio and back in may 1944 (about 120 km total) and lost 12 tanks to complete mechanical breakdown. That is basically one immobilization every 10 km on dry, paved roads.

[pamak1970]

i think the following link can be useful (not the final answer) for the question of immobilisation.

It shows breakdown of UN casualties in Korea (including Sherman tanks) by all types of cause. It shows both total casualties and complete losses (write offs).

It includes statistics from the period when UN controlled battlefield and from the period of fast retreat against Chinese forces.

It has breakdowns (mechanical) by type of tanks (and type of mechanical failure ,table 2 page 285!) and "terrain casualties". The latter is relevant with the harsh terrain conditions in Korea.

You will notice that the percentage of recoveries for mech breakdowns and terrain casualties falls dramatically during the withdrawal cause of lack of time and equipment to recover those tanks.

The link is the following ( it is almost 27 MB download but it is worth waiting for it)

Go to

http://209.85.173.132/search?q=cache:HUgLtPJC5JYJ:www.koreanwar-educator.org/topics/reports/index.htm+the+employment+of+armor+in+korea+pdf&cd=1&hl=en&ct=clnk&gl=us

scroll down and select

"Employment of Armor in Korea, Vol 1, Operations Research Study (PDF File) "

[dieseltaylor]

Combatintman

I really don't think anyone expects BF to change their decision. The thread is now really on the concept of bogging and how real life! measures up to the games. We all bumble around looking for some enlightenment. I see above we may have some - even if it is 27MB.

SO all the palaver is not wasted. : )

[pamak1970]

From the above link

Trafficability

Movement of tanks was generally confined to the roads. The

roads are of rough but heavy construction and have crushed stone

bases. Roads, except in mountain areas are built from 5 to 20

feet above ground level and have 45 to 60 degree shoulders.

Mountain roads are narrow and winding,with many sharp curves and

steep grades, and have no guard rails or fences of any kind. In

many instances bridges of insufficient strength had to be bypassed

which was generally not difficult in the south. But bypassing

often presented formidable problems in the north, where ravines and

and gorges of considerable depth had to be crossed.

Unfrozen rice paddies could be crossed where there was a firm bottom a

foot or so below the sludge , provided that the tanks were not

steered in the paddies, but prior reoonnaissance on foot was necessary

to determine the depth of the sludge. Tanks could go from

one paddy to another if the intervening dikes were not more than

2 to 3 feet high; higher than this, the tanks would dig In, become

mired, and often throw their tracks. The rice paddies could

be traversed when frozen provided the tanks did not follow in each

others tracks, which might cause the solid surface to give away.

In an attack demonstration, one M26 managed to climb a 2,000-foot,

30.degree slope consisting of terraced unfrozen rice paddies, but

the tank threw both tracks making a slow turn near th8 top.

In the north, light snow and considerable ice were encountered;

these caused tanks much traction trouble. Tanks equipped with the

T81 and chevron-type, steel tracks had great difficulty with skidding

and sliding, particularly when trying to negotiate bends.

Tanks sometimes kept one track in the shallow ditches of the mountain

roads to insure staying on the road. Ths Tank Company of the

17th Infantry, in a road march from Chori to Pungsan, climbed

4,600 feet in 11 miles, with many deep bypasses of 50 to 500 feet.

The first tank took two and one-half days to make this trip. Another

platoon of the same company had to shovel ice and snow off

the road in order to negotiate a mountain pass.

The 3rd Reconnaissance Company,'with rubber-tracked M24's

found the performance of these

vehicles on ice and snow much better than steel tracked vehicles

such as the M39. All units had to be careful to prevent an accumulation

of frozen mud and snow behind the drive sprocket, which

caused many tracks to be thrown."

Under the above conditions and in a period of 4 months , X coprs armor units experienced

(Figures in parentheres indicate total losses)

Cause..................Prior to wonsan landing...............After Wonsan landing

Mech failure...........46(1)..............................................54(26)

Tank fire.................4(2)...............................................0

Infantry attack.........0...................................................3(3)

TERRAIN..................3(1)..............................................17(17)

Mines......................9(1)................................................1(1)

AT guns...................4(2)................................................3(3)

Mortars....................1(0)................................................0(0)

Tactical abandoment...0....................................................6

PS (tactical abandoment from other parts of the document seems it does not imply cases of bogging down)

Also in page 73 when there is a detailed break down of casualties by unit , it gives only one instance of "terrain casualty" as a result of "bridge failure".

From the same document

"These figures show the different conditions which confronted

tank units in the two areas. In south Korea, 10 percent of the

tank casualties became total losses;

In northeast Korea, 65 percent

were total losses. This was caused by lack of spare parts,

the great distances separating many tank units from their ordnance

supporting units , and the tactical situation. Many units could

have recovered, repaired, or evacuated tanks had sufficient time

been available. Many of the terrain losses, a large Item, could

likewise have been recovered. It is noteworthy that only one

mine casualty occurred in northeast Korea, and that only seven of

the losses resulted from direct enemy action. The 100 eases of

mechanical failure reported are broken down in Table II."

Of course it is quite likely that those types of reports do not capture the cases of mired vehicles recovered by other tanks for example of the organic unit. I assume those "terrain casualties" were of the type where it was nessesary to call special recovery vehicles which recorded the "job" and became available as a statistical number of studies like the one presented here.

Still , it gives an idea ( minimum thershold) of terrain casualties under the ciscumstances described above.

The way i see it, terrain casualties in this case is a big percentage.

mech failures appear in about 100 cases (and of course again we are talking most probably about serious enough mech failures which require special action outside of tank crew corrective actions).

terrain failures appears in 20 cases.

There are similar data for other units and that is why i pointed the link so that members can dig into it and try to establish a rough idea about trafficability and tank losses.

By the way, there is another link in a US (modern) manual which gives Probability of traverse of certain types of terrains. However it does not link this probability to factors like distance traveled). It basically treats the terrain as either negotiable or not depending on soil characteristics, moisture and so on. Since the measurement of such characteristics inserts a measurement error, this creates a probability (together with the vehicle characteristics) regarding the ability to traverse the terrain by the examined vehicle).

I did not post this link cause i do not think it is very helpful (although it appears at first glance to give the "ultimate answer").

However after close examination it is obvious that under this treatment the probability of traversing a certain type of terrain is the same regardless if the length of the path is 10 or 100 miles.

[pamak1970]

anyway, since i guess people would want to see the other link i mentioned before

go to

http://www.globalsecurity.org/military/library/policy/army/fm/5-430-00-1/CH7.htm

examine table 7-8 and the example where there is an attempt to determine trafficability based on the concept described in the chapter

"Fifty M60 tanks (102,000 lb) and 50 M923 trucks (32,500 lb) are to be moved from point X to point Y in the area shown in Figure 7-12. Movement must be cross-country because the roadnet is heavily mined......................... "

Notice there are numbers for "one pass and fifty passes" (like somebody mentioned here before about the deteriorating road conditions after the pass of multiple vehicles which can prohibit the rest of the vehicles to pass through the same terrain).

Notice however that this approach does not link adequately distance travelled to probability of traverse.

[pamak1970]

as a last comment , i know i have somewhere a file about an incident in the second gulf war relative to immobilisations.

It describes in detail ,hour by hour an incident of an ambush by insurgents of a support element. The element was basically composed by delayed combat units because of immobilisations and recovering vehicles which came to their assistance. The information was sufficient to calculate the percentage of initial combat vehicles which fell behind cause of terrain difficulties. It obviously includes ALL cases of immobilization occurred during the marching of a battalion strong combat force for a certain amount of miles in Iraq.

Maybe it is somewhat irrelevant for the specific terrain and historical data here plus it is just one event only , but it is still neat to read.

When i will have time i will try to find it and post it here.

[Aacooper]

I'm amazed Battlefront has basically answered the same questions more than the one time I'd have the patience to.

Bogging and immobilization will be adjusted by Battlefront until it feels right to them. It isn't going anywhere, and neither are some proportion of your tanks.

[Battlefront.com]

pamak1970,

Good sleuthing I particularly love this link of yours because it shows how massively complex bogging is. But nowhere in there did I see it say "if you drive down a road you'll never have a problem" or "commanders will note that if they memorize all of this data that they can completely avoid bogging".

BTW, there is a famous bit of footage of a Sherman in early winter 1944 sliding backwards and to the left down a very mild sloped road surface. Both tracks are at times going and not going, yet the tank keeps sliding anyway. Soldiers are seen running out of the way of the oncoming tank. My guess is that didn't get itself out of the situation it was in very easily. Based on my memory of the footage I would guess the driver would have gone backwards along whatever stopped his tank (IIRC a house) until it got to the place where it wasn't sliding. Then, after consultation with troops or (more likely) getting out and walking the ground, would drive in an alternative direction. Metal grousers on "hard ice" ice suck.

The information was sufficient to calculate the percentage of initial combat vehicles which fell behind cause of terrain difficulties. It obviously includes ALL cases of immobilization occurred during the marching of a battalion strong combat force for a certain amount of miles in Iraq.

Good point and it is one I made earlier. You can have a very low average for a large force, but for a tactical component there could be an unmitigated disaster. The battle of which you speak is one I did mention earlier, specifically the Marines in Nasiriya (aka "Ambush Alley"). If one took the number of immobilizations for that one battle and extrapolated it for the entire OIF campaign the theoretical numbers of bogged vehicles would have been massive. If instead someone took the higher level numbers and extrapolated them, they would indicate that such a situation could never have taken place based on statistical probability. Which is once again why I think taking very high level statistics and trying to approximate extremely dissimilar tactical circumstances is a waste of time.

Aacooper,

I'm amazed Battlefront has basically answered the same questions more than the one time I'd have the patience to.

Debate keeps us on our toes, so it's good to do every so often. But you are correct... if we had to experience a 20 page thread for every feature in CM we'd be releasing CMBO right about 2011

Steve

[MikeyD]

Way back in late 2001(!) I was tracking progress of the Marines at Camp Rhino Afghanistan through Marine corps news briefs. At one point a task force of Marine LAVs and Humvees set out on a cross country trek to cut the 'Route 2" highway to Helmand province. According to the press reports the journey was straight out of hell! Every vehicle in the group had to be unditched at least once. Helos had to swoop in to ferry spare shocks and tires and to lift out Humvees broken beyond repair. It took twelve long hours of driving like this just to reach their first basecamp along the route. So even with modern top-of-the-line equipment bogs and ditching over open ground can be a real tactical headache.