Don't understand

[Johno02]

Dear Daughter (OTR Semi Driver) called to ask me what part of "CLOSED to High Profile, light-weight vehicles" do RVers not understand?? So far today she has seen four RVs rolled off the road (I-80 in Nebraska) today.

[drsteve]

colliehauler wrote:

valhalla360 wrote:

colliehauler wrote:


No where did I say that RV'S blow over at a higher rate, in fact just the opposite.

I don't know if the facts support your statement or not but if it's the opposite, that would imply truckers are more of a danger in high winds if they are going over at a greater rate.

PS: While trucks tend to be heavier, that's not the only factor. They also tend to have a higher center of gravity and wind resistance (generally). Your average semi is around 13' high and the floor is 4-5' off the ground. Bumper pull TT the floor is rarely more than 3' off the ground and even big 5ers are lower than a semi. Most RV's are under 11'. That gives the wind both additional area and leverage to flip the commercial truck. It could negate a good deal of the weight difference. Particularly for a commercial truck running empty.

Semi's box trucks running empty have a lot of surface area without much weight . Living within 30 miles of I-70 you hear on the news of truck blow-overs. There is another neat video of a trucker that saved it from a blow-over. The truck was about to go over when he turned in the direction it was going went through a ditch and fence into a feild and saved it.

Truckers tend to drive no matter what, while RVers generally have the option to say "screw this" and park it until the weather improves.

[colliehauler]

valhalla360 wrote:

colliehauler wrote:


No where did I say that RV'S blow over at a higher rate, in fact just the opposite.

I don't know if the facts support your statement or not but if it's the opposite, that would imply truckers are more of a danger in high winds if they are going over at a greater rate.

PS: While trucks tend to be heavier, that's not the only factor. They also tend to have a higher center of gravity and wind resistance (generally). Your average semi is around 13' high and the floor is 4-5' off the ground. Bumper pull TT the floor is rarely more than 3' off the ground and even big 5ers are lower than a semi. Most RV's are under 11'. That gives the wind both additional area and leverage to flip the commercial truck. It could negate a good deal of the weight difference. Particularly for a commercial truck running empty.

Semi's box trucks running empty have a lot of surface area without much weight . Living within 30 miles of I-70 you hear on the news of truck blow-overs. There is another neat video of a trucker that saved it from a blow-over. The truck was about to go over when he turned in the direction it was going went through a ditch and fence into a feild and saved it.

[valhalla360]

colliehauler wrote:


No where did I say that RV'S blow over at a higher rate, in fact just the opposite.

I don't know if the facts support your statement or not but if it's the opposite, that would imply truckers are more of a danger in high winds if they are going over at a greater rate.

PS: While trucks tend to be heavier, that's not the only factor. They also tend to have a higher center of gravity and wind resistance (generally). Your average semi is around 13' high and the floor is 4-5' off the ground. Bumper pull TT the floor is rarely more than 3' off the ground and even big 5ers are lower than a semi. Most RV's are under 11'. That gives the wind both additional area and leverage to flip the commercial truck. It could negate a good deal of the weight difference. Particularly for a commercial truck running empty.

[d3500ram]

Chum, Lovely! I will not second guess your numbers... like it that you end with a conclusion! That reply certainly does take me back to my days of DE and physics classes! Love it when folk analyze stuff like this (seriously)... but now-a-days I only enjoy the discussion and subsequent theses as I get another snifter of brandy. I am happy now to design and then pass on to our engineers to make it work. Awesome stuff and kudos to the engineers who make stuff happen!

[Veebyes]

Chum Lee, We will all keep that formula in our heads.

These days if breezy, even well below 30mph forecasted I travel with full water, 100 gal, & keep an eye out for flags, water surface of ponds, trees, even tall grass for wind direction & speed.

Experiencing a blow over is no fun & not quickly forgotten. Had we been a class A we might not be here today.

[Chum_lee]

"All RVs are basically boxes of air. Nothing to them. They have a huge amount of windage. Traveling in still air at 60mph is no problem however if a 60mph gust of wind hits them broadside then there is a huge problem."

Crosswinds are an equal opportunity destroyer. They don't care what vehicle is being driven. The physics are generally the same.

The general formula to determine the wind load on a flat surface is

L = 0.00256 x A x W^2

L = the overturning wind load in lbs.
A = the loaded surface area of the vehicle in square feet (usually the side of the MH)
W = the crosswind wind speed in miles per hour

This is a greatly simplified equation for static conditions. Rollover forces are always dynamic, change rapidly, and are much more complex.

So what does this mean?

Suppose you have a 30 foot class A MH. The side area is approx.

9' high x 30' long or A = 270 square feet.

If you have a 40 mph crosswind the force on the side of the MH is

L = 0.00256 x 270 x (40)^2 = 1106 lbs.

Now what happens if you hit a sudden crosswind gust of say 70 mph? Since the wind speed is squared, the force is now

L = .00256 x 270 x (70)^2 = 3387 lbs. (more than triple)

It may seem inconsequential, but when combined with driver inputs, road conditions, suspension dynamics, and a few other things, it can be enough to put you on your side, or, in a ditch, very quickly. It's usually the crosswind GUSTS that get you. Not the constant steady crosswinds.

Chum lee

[MrWizard]

unless new and being delivered
most RVs have stuff in them, food ,water, LP, clothes, gear etc..

a semi that dropped his last load, could be empty and moving on to pickup the next load

that makes for a TT very easy to turn over in high winds

hundreds of trucks go by and one gets flipped
could be good chance that one is empty or near empty

my old man drove for many years, but he carried heavy loads of equipment on a Low-Boy, never pulled a box trailer

[Veebyes]

All RVs are basically boxes of air. Nothing to them. They have a huge amount of windage. Travelling in still air at 60mph is no problem however if a 60mph gust of wind hits them broadside then there is a huge problem.

There is not much one can do to make the RV more stable. Be aware of weight & where it is. Lots of RVs are far from balanced with all kinds of heavy stuff on one side & light on the other. About the only thing that can be done on windy days is to travel with the water tank full. The more weight down low the better. Best to get off & stay off the road till the wind drops.

Wind warning signs are not always lit. We drive along, windows rolled up, oblivious to what is going on outside, especially on the open lands of the western states.

Some 5ers tow so well that there is no sign of exceeding limits till it is too late. Happened to us in 2009 on I80, WY, Elk Mtn. Got caught in a huge sustained gust broadside & over the 5er went. Tore itself right out of the hitch & rolled down a 50' embankment. Totalled.

I maintain that the extra stability of the dually saved our backsides that day. The truck stayed upright & on the highway shoulder.

[colliehauler]

valhalla360 wrote:

colliehauler wrote:
I think it has more to do with truck drivers have to be at a destination at a certain time and push the limits and the number of trucks on the road compared to RV'S.

So if they are on a schedule, the laws of physics don't apply?

These are "professionals" who have much more experience and training knowing what their rigs can handle...but they still fairly regularly blow over.

I've seen no evidence that RV's blow over in at a higher rate (not absolute number) than commercial trucks.

Not what I said at all.

I see more trucks blown over because a lot of times there pushed to delevering their loads on time and drive in conditions that are less then optimal. RV'ERS usually have the luxury to wait it out.

Fact there are more Semi's on the road then RV'S. I attribute both of these to why I see more Semi's blown over the RV'S in Kansas on I-70.

No where did I say that RV'S blow over at a higher rate, in fact just the opposite.

There was a good video a few years ago of a semi being followed by a truck pulling a travel trailer. The car behind both vehicles had a dash cam that caught the semi being blown over while the travel trailer remained upright. I seen the video on the weather channel. Probably some where on YouTube as well.

[73guna]

BarabooBob wrote:
Did you ever think that more trucks turn over because there are thousands more trucks on the road?

This^^

[4x4van]

Johno02 wrote:
Dear Daughter (OTR Semi Driver) called to ask me what part of "CLOSED to High Profile, light-weight vehicles" do RVers not understand?? So far today she has seen four RVs rolled off the road (I-80 in Nebraska) today.

Ummmmmm...wouldn't that warning also apply to your Dear Daughter?;)

[wa8yxm]

ken56 wrote:
Since when did people start reading signs on the highway? Speed limit, lane closed ahead, merge. Common sense isn't all that common. I won't tow if winds get over 40mph, and that is bad enough.

You have a point.. I recall years ago. I mean YEARS ago.. I was riding shotgun in a F-350 Custom (10K straight truck) as we went down the highway.. Our plan was to pass the closed entrance ramp to the freeway turn left and go about a quarter mile to the next ramp (about 1/2 mile total) Radio had reported closure of ramp as had TV news. Multiple signs going back about a mile said "RAMP CLOSED AHEAD USE 11 MILE RAMP" (Which was our plan) Two women in a convertible to our right had the most amazing "When did they put up that barricade" look on their faces.

[JaxDad]

Johno02 wrote:
Dear Daughter (OTR Semi Driver) called to ask me what part of "CLOSED to High Profile, light-weight vehicles" do RVers not understand?? So far today she has seen four RVs rolled off the road (I-80 in Nebraska) today.

“Light-weight” is a very relative term, a 7,500 pound RV is a heavy vehicle to someone driving a 1/2 ton pickup, to someone driving an 75,000 pound semi it’s not.

[valhalla360]

colliehauler wrote:
I think it has more to do with truck drivers have to be at a destination at a certain time and push the limits and the number of trucks on the road compared to RV'S.

So if they are on a schedule, the laws of physics don't apply?

These are "professionals" who have much more experience and training knowing what their rigs can handle...but they still fairly regularly blow over.

I've seen no evidence that RV's blow over in at a higher rate (not absolute number) than commercial trucks.