"Realistic road speeds help wanted." Topic

OK so MG has reached its limit at 10k road distances as the rules may begining to be to be optermistic about road speeds for long distances (over 3km). A quick trawl through the manuals gives max speed for my sort of convoy of 25mph. That does not seem practical for most tracked vehicles. So guidance wanted on what speeds are representative on modest (not motorway) roads. As per the Terrain facts post road. The Jeb Stuart Memmorial Rally (the run to Bagdad Airport)was about 12km/hr.

I guess Roiad speeds of convoys is a big issue for the large games (battalion and above), the large scale gamers cannot possibly play realistical without this data so there may be some good well designed simple rules to help based on typical real world data.

Posted speed limit on the maintained dirt/gravel road to Orchard Training Area is 35mph for wheels and 25mph for tracks and heavy trucks. "Modern" vehicles like my 1994 Jeep Cherokee or a Humvee can easily do 45mph on it, at the cost of a lot of dust.

Humvees and the rest of the wheeled trucks can convoy on the Interstate highways at 65+mph, though usually do 55mph.

M113s, Bradleys, and Abrams can all maintain 25-35mph on a dirt road. Abrams can get stupid-fast if the mechanics disable the governor, and the Bradleys are supposed to be able to keep up with the Abrams.

But that's "route march", with no expected contact with trouble.

Once you start having to eyeball every single pile of garbage for IEDs, and every hilltop for RPG ambushers, well, I'd expect to slow waaaaay down.

REFERENCE DATA The Infantry School,Fort Benning, Georgia (1942) TABLE 2 – Rates of Movement
gives the following figures for average rates of march (mph) on road by day/on roads by night/across country by day/across country by night/ and miles per day on roads:
Foot troops 2½/2/1½/1/12-15 for division, 15-20 for smaller units
Artillery – Light and AA 25/25/8/5/175
Artillery – Medium and Howitzers/20/20/8/5/140
Artillery – Heavy (Trk) 15/15/85/100
Artillery – Heavy (Trac) 5/5/3/2/40
Tanks – L & M (under own power) 25/25/15/5/150
Trucks, motorised units 25/25/8/5/175
Cars, passenger 35/35/8/5/250
Cars, armoured or scout 35/35/10/5/200

Without lights at night on roads the average rate for vehicles is 10mph, except Artillery – Heavy (Trac), which averages 5mph.

Greater distances per day may be covered under forced march conditions – in one 24 hour period 35 miles, in one 48 hour period 60 miles, in one 72 hour period 83 miles. Forced marches of more than 72 hours duration are not considered likely, as it will almost invariably be possible to make motor transportation available (Table 3a).

For movement over mountainous terrain an additional allowance of 20 minutes should be made for each 1,000 feet of climb.

In Baghdad we usually rolled at ~ 45 mph, expecting contact in 4 vehicle Humvee column

25 MPH is surprisingly slow.

I think the post immediately above is probably very accurate, and realistic.

Probably depends upon the vehicle, and terrain, too.

I recently read that the cross-country speed of the M48 tank was about 8 – 10 MPH, due to its weight to power ratio.

Obviously, more modern tanks and IFVs/APCs/Scouts would be a bit more agile than that.

Divisional march rates tend to be rather less than the march rates of individual elements as you have to take account of the length of the columns (essentially you have to count the time it takes for the formation tail to pass the start line, which for a 40km long column takes quite a while). ergo, formation march rates are proportional to the number of parallel roads available as well as the mode of traction.

Staff tables cover that sort of thing too.

As for tracked vehicles, 25mph was about all that most WW2 tanks could do flat-out on an autobahn!

Those rates John posted sound generally pretty accurate to me … I'd go with those …

I am bit biased as I'm a grad from The US ARMY Infantry School, Ft. Benning, GA. Or as we used to called it, "The Benning School For Boys" … but that was 1979 not 1942 …

Bear in mind too that with any group of vehicles, you're going at the speed of the worst map reader combined by the worst driver in the column and modified by the single vehicle most likely to get stuck in a microscopic, yet fatal, hole in the ground :-)

By night time, multiply by the "I'm sure we've definitely followed the right path, its just a coincidence we haven't seen the rest of our column for 3 hours" factor.

There's some information in the following manual. Hope it helps!

PDF link

OK so MG has reached its limit at 10k road distances

What does MG stand for?

What does MG stand for?

Manoeuvre Group (wargames rules):
link
TMP link

Extra Cripy,
MG stands for Manueouve Group of which I am co-author.

link

The design parameters of MG did not envisage 10km road movements along essentialy straight roads with very large units (20 vehicles plus). It has worked up to 5Km OK but 10km may have been pushing it and it may represent too high a speed, and be significant. At shorter distances the time taken to deploy onto off the road dominates so any inaccuracies are negligable.

It may be, having read thesae excelent posts this that convoyes can happily maintain cohesion at 20 mph or more some the rules are not really broke. As a bound is 6 min it would only take a convoy 20min (just over 3 bound to cover 10k). in reality given this is the FEBZ in part convoys are likely to be only 5k so close enough to 1 bound in transit mode so no issues. Long off road marches are not prectical in a european theatre so no issues there.

May be in some desert terrains it could be an issue but the games we as the authors are playing are well beyond where we would expect most folk to play.

Remember a convoy can only go as fast as its slowest vehicle.
I could only get the M109 van (2 1/2 ton box bodied van) I drove in the US Army in the '80s up to 35 mph, top speed. Pulling a trailer, up hill, etc… I would really slow down.
pjm

Obtw, the Abrams were usually rolling even faster than our Humvee conveys on the MSRs in Baghdad. There was so much debris, trash, damage on the roads in eastern Baghdad that we were unable to effectively assess and mostly just ignored it. Off road we slowed down a lot (sidewalks, land fills, agricultural areas, etc.) Going as fast as we could and keep our teeth. That was in 2006/2007 reflecting an extremely hostile environment where speed was life and trying to avoid ambush sites abd traffic jams.

Old saying from the RANGER School at Benning … "Speed is Security" …

25 MPH is surprisingly slow.

Yup, but it's the posted speed limit on that road, which implies that the vehicles can (relatively easily) exceed that speed.

An invariable rule of convoy movement is that the lead vehicle motors along sedately at 15mph while the rear vehicle roars along at top speed in a cloud of Dust trying to keep contact.

A WW2 tank commander said that, and it is due to the compression and extension effects of group movement. Just look at queues of traffic on the motorway, and this stuff is indeed covered by the mathematics of queuing theory. The same thing happens with foot columns, even if everyone keeps step.

So column speeds need to be set somewhat less than the theoretical maximum speed of each element, or they break up.

Whether mounted or dismounted based on terrain, most columns of troops/vehicles will experience the "Accordion Effect". But I don't think it may be needed in most games based on scale.

BTW … Maneuver Group would be – M/Gp

MG = Machine Gun

Abbreviations don't work if not everyone understands them …

Well, as an unrepentant rules junkie I had never heard of them before, so interesting to discover a new title.

The blurb on wargame vault gives no clue as to ground scale though?

I'd say it would depend on the turn time/distance scale and table size. If your turn is a hour long and it is 1:1000 scale I'd say you need a real big table or cut down on turn length for a 25mph mover.

Also depends on size of moving force. Small forces almost always move faster than large forces, due to all the screw-ups mentioned above. The more troops/vehicles, the more chances for Murphy's Law to take effect.

BTW … Maneuver Group would be – M/Gp

MG = Machine Gun

Abbreviations don't work if not everyone understands them …

I agree, I just happened to know what UshCha meant by MG as he mentions them fairly frequently in his posts. If it had been someone else posting, I would have thought machine gun! :)

just a factoid

The Germans in WWII planned that a motorized division could make a road march of 250 km a day.

40 km a hour ten hours, with a couple to get on way and a couple to shake out after.

MG (M/Gp) runs at a scale of your chosing but we recommend 1mm = 1m or 1"=10m using 1/144 or 1/72 models respectively.

By using the board in interesting ways using 1/144 scale models we can get a decent representation of a 10k road on the board (see recent topic terrain facts) and
link

A German battalion is 48 vehicles so at about 50m spacing and a bit for the vehicle you get a column 2.6 km long. This may well have to be on table as the column won't want to deploy much further than 3km away from the enemy due to the difficult terrain off road. So it could easily get stretched with quite small but necessary speed limitations on sections of the road leading to potential problems. Certainly we would not need to put the obligatory 10min breaks in on such a short distance.
Hence how to set a speed that is reasonable without having to go to extremes is sensible. With a sharp bend then hell breaks lose but none of the roads a large convoy would want to travels would have such things if it could possibly be avoided.

LORDGHEE that is in line with current close colums (25 to 50m spaceing) limit speed 25 mph. Some things don't change that much!

I recall reading that in NW Europe the expectation was that a road convoy would advance by 12mph in friendly territory and 2mph into enemy territory.

hagenthedwarf # Thats the sort of info I was looking for. Any idea what the source was?

Here's another manual that I think is fairly recent. Its the Army manual on convoy movements.

link

If you scroll about a 3rd of the way down there's a table listing conditions and movement rates recommended. It also references road and weather conditions. Again, hope this helps!

50m spacing

That would last until the first big turn. Then 20-75m would be more like it.

Thats the sort of info I was looking for. Any idea what the source was?

Sadly not; probably in some memoirs.

The British army method or the one i followed was to "try" to keep in visual range of vehicle in front, the vehicle in front should if he lost visual of the vehicle behind, should slow down. Which usually resulted on a big line of wagons pulled over wondering what happened to the rear vehicle?

Picture the convoy as an 'accordion'…..spaced perfectly at one moment but compressed and then stretched out the next………I recall taking part in a 'loaded for war' road movement and the trucks could barely manage 20 mph in places flat out……caused some rethinking and planning of load outs and route march order……………

Yes, as I said, whether mounted or dismounted based on terrain, most columns of troops/vehicles will experience the "Accordion Effect". And no matter what the situation, you don't want a "break in contact" !

The "accordion effect" can be seen in action at any traffic intersection stoplight when the light turns green.

B

Load can make a huge difference. My M577 could unloaded on the flat desert do just a bit over 30mph wide open. Any rough terrain, me and the driver could not take the pounding.

Once we had all the ammo, and extra crap various senior people had us load up, including a bunch of sandbags, we could barely make 10 MPH.

As we started training, the m1s would roar across thedesert at 40-50 MPH or more leaving us way behind. but as we got closer to actualy kicking off the ground war, they got slower and slower, until we finaly settled on 15mph as the max the howitzers could sustain cross country. And I threw away junk we didnt need until we could keep up.

So it isnt just the speed the armor can go, but the speed the various support weapons can go. Going to feel kind of silly when red air rools in and you left the Vulcan back outside its range.

owen

The "accordion effect" can be seen in action at any traffic intersection stoplight when the light turns green.

Yes … but all those on the road are not usually going to the same locations, don't have to try to keep an interval, and may not be on a timeline with other convoys, etc., …

Load can make a huge difference. My M577 could unloaded on the flat desert do just a bit over 30mph wide open. Any rough terrain, me and the driver could not take the pounding.

Once we had all the ammo, and extra crap various senior people had us load up, including a bunch of sandbags, we could barely make 10 MPH.

Agreed … been there, done that … in the ROK, [West Germany, and in the US, etc., including the NTC …

In many cases the answer to the original post/question is – It depends on many variables … So for gaming purposes, to "generalize" may be the solution ? Again based on game scale …

Thanks for all the info. I'm just back from holday and have re read it all again.

It turns out that with only 10km to worry about the exsisting rules are still valid and I don't have to write any more. In the dark. blacked out and no FLIR it is a marginal issue at 5 mphas its about 1/2 to 1 hour to cover the board (we would notionaly call that 3 to 6 bounds). However in reality no vehicles will go that far as the game will have ended by definition. So not worth worrying about the odd bound, as getting into coloum and out again will be the lions share of the delay anyway and that is covered.

Thanks again for all your help.