Building an entire truck isn't free from cost and environmental impact, nor is maintaining it.
Fuel usage also increases with more trucks.
There's also an overhead each truck has that scales differently from how much it lugs, based on fuel it needs to carry and space for its driver.
On the other hand, wouldn’t reducing the amount of cargo a single truck can carry makey individual truck driver less valuable?
The end result would probably depend on a lot of other factors, including the supply and demand curves for alternative forms of transportation (trains, boats, investment in autonomous solutions), as well as the supply and demand curves of the goods being transported (because if the cost goes up to pay for more truck drivers, maybe people will just stop buying that product).
My truck gets at least 6mpg, usually 7.5, sometimes 9, and I've seen 10 once.
However, an even more material-efficient solution would be to use railways instead.
You're absolutely quibbling though.
> So you should include in your calculations that the load is spread out over eighteen tires, as above.
The fourth power rule is specifically about axle load, not about wheel load. It's also an estimate / rule of thumb (which is why it's so useful), not a precision instrument.
But hey if you want more precision than the FPR we can do more precision: https://pavementinteractive.org/reference-desk/design/design...
As the link notes, road engineers usually work in LEF/ESAL (ratio to a standardised 18000lbs axle load), and provides some conversion tables.
Assuming a relatively large 4000lbs sedan this is 2000 lbs per axle, or 2x0.0003 LEF = 0.0006 LEF.
A fully loaded truck would be ~0.3 for the 12000lbs front axle, and 1.11 for each of the rear tandem axles, for a total of 2.52 LEF.
2.52 / 0.0006 = 4200. Which shows that the fourth power rule's 4096 was pretty close but if anything underselling it.
Misunderstood that, sorry.
But, there is also something called a "super single" that's a double wide single wheel/tire, with one on the end of an axle rather than two. I'm told they're cheaper and lighter total, as opposed to the more common two per end. I've pulled a few trailers that had them. I don't really know why one or the other, I just drive them.
Let's not forget the context of this discussion, however. Fourth power expressions are still fourth power expressions after multiplication by a constant factor. 4/18 is a constant factor.
I don't know if doubling tire counts really does this, but it's hard to see why twice as many axles would help but tires per axle would not. It's possible (the pressure underneath the tires is reduced, but the tires exerting pressure on the road are closer together) but counter intuitive to say the least.
And there's no proof in this thread that it doesn't help except for masklinn's misinterpretation of the original study.
Truck driver. Not quibbling, just adding nuance.
For your typical 40t scenario, allowed max weights are:
12,00 pounds on the front steering axle. It has one tire at each end.
34,000 pounds total on the two tandem "drive" axles on the truck. There are two tires at the end of each axle, so four per axle, eight total at the drive axles, and ten total on the truck.
34,000 pounds on the two tandem axles on the trailer, two tires at the end of each axle, eight total on the trailer axles, 18 total on the truck plus trailer rig.
34K + 34K + 12K = 80,000 pounds = 40t, if the trailer is fully loaded to max. It's about 35,000 pounds total if the trailer is empty.
So you should include in your calculations that the load is spread out over eighteen tires, as above.
There is also bridge loading to consider. https://en.wikipedia.org/wiki/Federal_Bridge_Gross_Weight_Fo...