Tractor, Truck or Car - heaviest per square inch?

[slowrev]

One thing to consider. If using R1 type tires then the pressure is more restricted to those narrow points whereas the truck weight is spread out evenly on the tires surface.
Not use which is causing the damage though, this is just a consideration.

 

[coveredbridge]

</font><font color="blue" class="small">( </font><font color="blueclass=small">( So what does more harm to the gravel road? Absolute weight or weight PSI?)</font>

PSI weight is what harms the gravel road... based on my limited experience accessing load carrying capacity of soil types. (once again in my limited experience, always expressed in PSI, not absolute weight) )</font>

Ok. I know less about this subject than anyone else here, I'm certain. So, somebody explain this to me like you would to a 4 year old, because it doesn't seem logical to me.

I found this on the web:

"The dozer is equipped with a diesel engine and is supported on the ground by a track assembly. The track assembly provides all-type-terrain versatility due to the low ground bearing pressure at the track. This lower ground bearing pressure, varying from 6 to 9 pounds per square inch, has a distinct flotation advantage over rubber-tired equipment ground bearing pressure that varies from 25 to 35 pounds per square inch."


It seems to me that at some point the area of the tire (or track in the case of a dozer) that is in contact with the ground needs to be accounted for. Common sense tells me that if I run a track dozer over a typical paved driveway, the track cleats are going to dig in to the asphalt, yet the track is only exerting 6 - 9 psi pressure on the pavement. Likewise, I've seen many posts on this site claiming that bar tires will tear up sod while turfs won't, but I think the psi in either is roughly the same. Same principle applies with tire chains or studs, I would think. So what am I missing here? /forums/images/graemlins/confused.gif

 

[Highbeam]

My opinion, as a civil engineer, is the high point loads from small tires do more damage than overall weight but both have a bearing on road life.

Reason being that the point loads actually cause the road base to deflect or yield under the pressure in a small place. This deflecting rolls like a wave away from the tire as it drives. This wave causes the base to squish around and slide against itself. We call it pumping and it's bad. Some deflection is elastic and the road goes back to normal, higher levels of deflection are plastic and the road does not return on its own. A rut/pothole is born.

Take this to extremes and run a 30,000 lb wide track (LGP for low ground pressure) bulldozer down a gravel road. The road will not deflect much at all and what little deflection occurs is very small and spread out like working dough with a rolling pin. Take a 30,000 lb concrete truck and the wheels from that truck will sink/pierce through the roadbed like a fork through your dough.

This is a single trip way of thinking. If you look at the number of trips method then it is certain that a heavier vehicle with the same psi loading on the road because of larger tires takes more life per trip out of a road than a lighter car with the same psi. If you take less trips per year with the heavier tractor than it can be a wash.

The official method is using ESALs or equivalent single axle loads. The single axle is a given weight over a given surface area. The larger weight of the tractor just means that it is equivalent to more ESALs rolling down the road. The life of a road is provided in ESALs so a vehicle with more ESALs takes more life out of the road per trip.

In my state, the grantor of the easement can not do anything to prevent the grantee from enjoying his easement across the grantor's property. The terms of the easement may dictate a maintenance agreement. Even if the majority votes to pave the road, there is no legal reason you would need to pay for it unless you signed an easement with such language.

 

[zbeckerd]

PSI does the damage. The US Forest Service did an experiment a dozen years ago on logging roads. Fully loaded log trucks (80,000 lbs) run at normal pressure 90-110 psi and took the pressure down to 20-38 psi on non-paved roads. Two things became apparent:
Lower pressure actually made the road better by getting rid of washboard.
No flat tires with the lower psi as it allowed the sidewall to flex around rocks.
Downside was having to air up before getting on pavement. This led to Central Tire Inflation systems which are now in use on many military and other off/on road vehicles.

 

[BillyP]

Bob, it looks to me like it would boil down to pounds per square inch. If you have one that weighs 10,000 lbs and one that weighs 4,000 lbs and each one were exerting the same PSI on the road, then what would be the diff? What would effect it more than anything else (this is me thinking) would be the road base and speed (shock load). Wider tires have a bigger footprint but affect more road surface.

 

[Bob_Skurka]

So is it pretty safe to say that for all this guys whining and complaining he is the cause of the potholes that he is blaming on the farmer?


zbeckerd . . . I would love to see some sources of the study by the forest service of the trucks on the logging roads, any clue if those are on the internet?


Highbeam . . . where can I find information about the stuff you posted? Specifically regarding this stuff: <font color="green"> The official method is using ESALs or equivalent single axle loads. The single axle is a given weight over a given surface area. The larger weight of the tractor just means that it is equivalent to more ESALs rolling down the road. The life of a road is provided in ESALs so a vehicle with more ESALs takes more life out of the road per trip </font>


Coveredbridge . . . what you wrote sure seems to be in sync with my question about the combine that crushes the wooden bridge. At some point the absolute weight has to be accounted for. But I can sure see how the PSI and its deflection issues as outined by Highbean can come into play too.


BillyP . . . you bring up an interesting point about the speed, shock load issue. Again, going up to Highbeams deflection issue, I would think that a high PSI tire going faster and hitting an uneven spot would then create more shock, and therefore more deflection, compounding the issue. So a slow moving tractor, combine, etc, while much heavier than a car, would have far less shock on an uneven surface than a faster moving car would and that doesn't even take into account the lower tire pressures.

 

[Henro]

Bob,

Regardless of the answer to your questions, in the end the neighbor will be sharing that easement with the farmer, and I would bet he will always find reasons to be unhappy about it.

I would suggest that he just define the edge of the esement, and run a new driveway that he has total control over along that edge. Mabye put up a fence of some kind to mark it.

Then it is his...he controls it...only he will damage it...etc, etc.

The easement was there when he bought the property. Accept it, live with it, avoid the stomach problems...if he were my neighbor that is what I would advise him to do.

Or course, a guy trying to get someone else to pay for something that will be of primary benifit to himself, probably will not want to hear such a thing... /forums/images/graemlins/frown.gif

 

[Bob_Skurka]

Ah Henro, your wisdom always cut through the junk, and in the end you are usually right. Your last sentence says it all.

As I live in a private neighborhood, and as I am president of the Property Owners Association, I am stuck in this whether I want to be or not. I've explained to this neighbor several times, as have others, what the reality is. He chooses not to hear it. And so he got himself elected to the board figuring he could change things.

He complained in written form, and I am doing due dillegence to be fair and honest. I obviously disagree, but I really didn't know the answer to the question that started this post, and that question is directly to the point of ONE of his MANY issues.

With P.O.A. board approval, I have also brought in my law firm to investigate "easements" and to provide a legal opinion for this neighbor. It will end up costing the neighborhood money, but far less than a driveway, and it should settle this issue once and for all. We had the EXACT same set of issues with the former homeowner who sold the house to the current guy 4 years ago. He's a nice guy otherwise and a nice family, but this one issue of easements simply is a thorn to him.

My advise to him, and to the former owner was exactly what you recommended. Put your personal driveway in a different spot, and if you choose, put up a fence where you have issues.

But this is an odd case because of the way the former owner situated the house on the lot when he built. It really takes great advantage of the easement and makes it an ideal driveway. The problem is, it is still an easement. The former owner not only wanted it paved for him, but also wanted us to plow the snow for him in the winter. Yeah, sure, we'll do that /forums/images/graemlins/wink.gif

Just a simple case of " I don't understand, but even if I'm wrong I'd still like it my way!!! "

I make enemies every time I get elected to the Board of Directors simply because I point out the rules. We have the ability to change the rules with a neighborhood meeting, but funny thing is every time someone wants to change a rule, it gets voted down in a landslide. Simply put, nobody wants to pay for things but they want everyone else to pay for them. Just doesn't seem to work that way. So I point things out in a nice, but blunt way. Sometimes it takes a 2x4 over the head. In this case, it may be a bit more than that because this problem KEEPS COMING UP year after year.

 

[hudr]

This thread makes me SO GLAD I live in the country with 1/4 mile of driveway (all mine) up to a dirt county road. The only two houses I can see from my yard are family (my parents and my sister) and they are at 1/4 mile away each. I am like the rest of the guys. It boils down to PSI. My dad has brought is Semi home (unloaded usually) for years with no apparent damage to our DIRT county road. We see more damage from speed (rubboards going into and out of corners) and ATVs than any of the farm equip we have run up and down the roads at low speeds.
It sounds to me like this guy needs reminding that this is just one of the trade offs for living in a semi-rural area. Why not just pack up and move into an apt where you don't have to worry about the driveway, yard or anything? I think we as a society are too quick to get our hackles up over little things.
Girly man needs another hobby.
Good luck

 

[jpm]

Ah the fun of urban vs rural life smacking into each other.The farmer has been there 100's of years ,the new guy say's this is
great, now get that farmer out of here! Bob if you cab solve that
quit your job,your on the road to world peace /forums/images/graemlins/smile.gif and road is the
subject , water is the cause of the pot holes. tell both the can't use
the road when wet .The farmer can live with that much eazier than
the neighbor .He may calm down,he may not good luck