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For people that don't watch the video (I don't even know if this is in the video): road wear is a function of axle weight to the fourth power. [0]

That means a 6,000lb escalade creates 3x the road wear than a 4,500 wagoneer from 1990.

[0]: https://en.wikipedia.org/wiki/Fourth_power_law

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The other key takeaway from the video is that carmakers are highly incentivized to sell SUVs because they're still classified as "non-passenger work vehicles", which have looser emission requirements making them cheaper to produce.

The bug in the law really seems to be that cars that really aren't intended as work vehicles are being treated like them.

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This model is the basis of the 1993 AASHTO guide on a flexible pavement design, which is not the state of the art, but is still commonly used. This is why pavement design is mostly controlled by commercial traffic. For estimation purposes, I would not even consider the load of passenger vehicles in a flexible, pavement design.
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You are incorrectly assuming the Esclade isn't on 32+" tires with 285+mm width and the Wagoneer isn't on pizza cutters. Tire size has increased greatly on SUV and light trucks, which exerts less ground pressure.

It's not realistic to do this on a heavy truck, which run 110+ PSI on heavy wall tires and why they cause the power law damage to roads.

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No way does the Escalade exert less ground pressure!

Firstly, a Wagoneer is never on pizza cutters. You can't put a 4500lb car on pizza cutters even in 1990! It came with 235/75R15 tires. They are big sidewall donuts, but no pizza cutters.

The Escalade runs 285/40R24 tires, that's wide and low-profile.

Widening a tire increases ground pressure, because low-profile tires have massive amount of reinforcement to prevent that wheel from cracking. This stiffness adds to the pressure the road feels.

Tire contact patch is a function of weight and tire pressure. A 205mm width tire has the same contact patch as a 285mm tire, given same weight and pressure. The only thing that changes is the shape of the contact patch, which becomes wide and short instead of narrow and long.

The 6000lb Escalade runs its 285/40R24's on 35 psi, the Wagoneer runs its 235's at 30 psi.

So assuming even weight distribution, the contact patch per tire is 6000lbs/4/35psi=42.8in^2 inches for the Escalade, and 4500lbs/4/30psi=37.5in^2. So the contact patch is only 14% larger on the Escalade, yet it carries 33% more weight!

If you look at the road wear formula, it's entirely a function of weight. So the width of the tires only impacts surface-level abrasion. And with the power law, that's still 3.16x of Wagoneer's wear (or 216% increase).

So the wider tires do virtually nothing to protect the road from the extra 1500 lbs weight.

In fact, the dynamic load when hitting potholes is greatly exacerbated by the 285/40R24 low profile tires, because instead of of absorbing the bumps within the tire, the stiff sidewall low-profile tires absorb way less.

The spring rate of the Wagoneer tires is ~1200-1500 lbs/in, the spring rate of the Escalade tires is ~2500-3500 lbs/in, so that's a 2x stiffer tire! As a result, it transmits twice as much force when hitting the same bump.

So as a result, an Escalade accelerates road cracking considerably worse than the Wagoneer, not even in the same league.

Yes, the heavy trucks wear the road outsizely, incomparably to the SUVs we are discussing. However, we have roads that do not allow trucks (parkways) or see little heavy truck traffic.

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The tire spring rate is not what is "felt" by the road every bump, there is forward motion and coilover suspensions in modern cars running low profile tires versus solid axles and leafs on the Wagoneer, but yes nearly every modern vehicle ships on low profile tires unfortunately.

We are talking a few hundred pounds of weight difference per tire, it simply doesn't matter in the real world. I maintain private roads and even if your parkway is placarded everything is subjected to vocational vehicles and HDTs whether signed or not, because work needs to be done and local deliveries are exempt from transit restrictions.

The road wear model is obviously simplified versus the real world, the power law accurately enough extrapolates to HDT axle loads. You can drive a vehicle above snow, or move million pound super loads without causing excessive wear by thinking in additional dimension.

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Keep this in mind next time some crank on Nextdoor dot com goes off about taxing bicycles. "Sure, as long as we're both paying according to the road wear and tear we cause".
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one garbage truck - 40,000 pounds wears road 2000x than escalade.
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We can't do without garbage trucks though
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- have less garbage

- collect garbage more frequently in smaller trucks

taiwan has very cute small garbage trucks and they have a ice-cream-truck like song signalling for people to bring whatever trashbags they have out to the truck, so you don't even have piles of garbage outside for days waiting for the weekly truck. quite nice.

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I only need the garbage truck to do a run for me and a couple hundred others once a week. My Escalade is transporting me and maybe 1 other person on average 7 days a week.
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I've heard that cars have negligible impact on roads. 99% damage comes from heavy haul trucks, especially those who violate weight restrictions.

By the way, I've never seen SCALES OPEN sign for the trucks, it's always SCALES CLOSED, or maybe I'm just extremely unlucky.

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I designed highways. This is correct, and this is why weight restrictions exist. Noncompliance is not that much of an issue, and there are occasional permitted loads anyway when there’s a need to haul industrial equipment or unusually large objects.

The most important thing to remember about flexible, pavement lifespan is that asphaltic pavements are not designed to last forever. The asphalt binder will eventually oxidize and become brittle even with no traffic. These surfaces are meant to be consumable bearing services that last for 10 or 20 years and then have to be removed and or overlaid.

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Thank you. What about concrete pavements? I assume they can last longer, but I often see badly cracked concrete. Regular (expansion?) cracks also don't increase riding comfort.
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Well there aren’t semis driving down your neighborhood cul de sac (at least I hope not). Heavy trucks cause more damage to interstates and warehouse districts, yes, but that is what those roads are designed for. Most city roads meanwhile were never built to accommodate 9000 lb hummer tanks.
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Most road damage here appears after events of the form "it rained and then the temperature crossed freezing twice a day for a week".
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I’ve done a lot of trips on I5 from Central Valley to San Diego and those stations were open most of the time and I usually did it near holidays in November/December/January. Enforcement probably depends highly on location and amount of traffic.
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The damage scales with weight. Cars cause less damage because they are lighter. Heavier cars still cause greater impact.
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Damage scales with the 4th power of weight.

From what I can find, the standard weight limit for a truck in 20 tons per axle (less when multiple axles are close together).

In contrast, the average weight for a car is a bit under 4 tons (even for SUVs). Even a pickup truck is under 5.4 tons. Since these have 2 axles, that comes out to every class except loaded freight trucks having under 2.7 tons per axle on average. So a freight truck acting at the legal limit (without tandem axles) would be over 7.4 times as heavy per axle as a passenger pickup truck. Applying the 4th power law, this means a single maximally loaded truck causes about 3000 times (300,000%) as much damage as an average pickup truck; and 10,000 times (1,000,000%) as much as an average SUV. In contrast, the difference in damage caused by an average SUV and an average sedan is only about 40%

https://www.autoinsurance.com/guide/average-car-weight/

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It’s extremely super linear, supposedly 4th power of axle weight. So it doesn’t make sense to argue over the relative size of mice when there are elephants around.
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I don’t think SUV vs car makes a meaningful difference when e.g. delivery vans and garbage trucks exist.
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Even if it were caused by passenger cars, the skyrocketing brightness of lights at sedan height probably push more people to buy large cars than this. In a just world, cars with ridiculously bright lights would be crushed in a monster car rally. Alas the cops don't even pull them over.
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The cops are some of the worst offenders. Drive past an accident and the blue lights are so bright you'll have after images for hours
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This is the sole reason I've always hated Teslas. Didn't care that they're EV and new and have stereotypes about the drivers, just that the lights are way brighter. Or sometimes pointed further up out of the factory for some reason.
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The one thing I noticed in NA is that it takes ages to rebuild a road. I have close to zero experience in road construction, but a bit weird to see how they can repave a km stretch of a road here in Tokyo within a week or two, but it took months in other cities i've lived in.

Maybe they do a lot of extra work over night over here in Tokyo, and it just goes faster? Or it's a very systematic thing and part of the maintenance schedules, so it doesn't really go that bad?

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Hmmm probably the only thing I’ve consistently noticed around the US is they can pave highways and roads very quickly. That’s the American skill: tons of sprawl and highways. You may have been confusing road repaving with gas or water pipe replacement
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People in cities generally want deliveries of goods, which requires heavy trucks.
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Heavy trucks aren't required for the vast majority of residential deliveries.

If you order anything in Bangkok, even say a refrigerator or a king size mattress, it will almost always be delivered by a modestly sized pickup truck (with a high roof covering the bed).

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How are we being forced to buy SUVs? There are plenty of regular cars for sale.
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I think another factor of road wear is better handling cars. People are able to drive more aggressively and accelerate more efficiently then ever before. Taking tight turns at high speeds or accelerating from dead stop does wear out roads more due to higher traction from driving behavior and characteristics…
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No one is "forcing" anyone to buy a "super heavy SUV. Make a better argument.
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Last time I bought a car, I was replacing my 2010 CRV. If I wanted to purchase a subcompact SUV or hatchback sedan that was smaller and more fuel efficient I would have needed to wait at least six months.

Economic realities do force decision making.

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Was this that one year when the whole auto market was completely screwed up? This is normally not an issue. Also why do you need a hatchback instead of just a regular car?
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That's not the full story. I presume it was some Toyota, which are in high demand. Plenty of small size alternatives are available from other brands with 0 wait time.
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This was spread across multiple makes and models. The car I wound up with is larger than I would like, but you're right, it was in stock. Because the dealers stock what people want and lead times (at the time) were atrocious.
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I could walk in to any number of dealers and purchase what you are describing tonight. I have an excellent electric SUV that I walked into a dealer an purchased.
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> Maybe roads would last longer if we weren't all being forced to buy super heavy SUVs

Maybe not.

Due to battery weight, EVs are super heavy even if they aren't SUVs, so are delivery trucks without which an urban community cannot and will not exist. Urban roads should be able to handle the weight even if everyone converted to EVs.

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This has little to do with EVs, and much more to do with the idea that whoever brings a heavier vehicle to collision, wins (and lives). Hence the propensity to drive truck-sized SUVs and actual F-150s with just the driver, and the light load, but the pleasant feeling of safety. Who's gonna survive in an incident of road rage gone bad, a Ford Explorer or a Fiat 500?

Coming back to the EVs, a small EV is a possibility, because it takes less power to move a lighter and smaller car. But would it sell on the US market?

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>it takes less power to move a lighter and smaller car

A smaller car has less space for battery than an SUV. Because batteries are extremely heavy, that smaller car needs to be overbuilt compared to its gasoline counterpart, which further reduces room for battery. Then, because safety standards are harder to meet with small cars, the smaller car needs to be overbuilt even more.

This means that you get cars that only have half the range a gasoline-powered car does, and the gas powered car recharges an order of magnitude faster than the EV does. Oh yeah, and the people who buy smaller cars like this tend to live in places where there's no charging other than going to a gas station anyway.

It wouldn't sell on the US market because better alternatives exist. It could sell on the Chinese market because there are no better alternatives.

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It takes less power to accelerate a lighter car, but about the same to keep it moving. And some of the energy is recouped during gen-braking.
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Even EV weight is tiny compared to haul trucks. Yes they have multiple axles (hence "18-wheelers"), but even then pressure on the road surface is much greater still.
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Typical meme. Passenger vehicles of any type cause negligible road wear. The weight of a sedan (say, 4000lbs) versus a light truck (say, 6000lbs) is just not significant, further the ground pressure will be close due to tire sizing (https://en.wikipedia.org/wiki/Ground_pressure)

Road wear is a power law, and heavy trucks cause the wear https://blog.ucs.org/dave-cooke/trucks-cause-the-lions-share...

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Correct, one of those “fun facts” of public policy is that (at least in the US) taxes and other fees, including on fuel, paid by heavy commercial trucks don’t come anywhere near paying for the damage they do to roads. The rest of us subsidize shipping-by-road with our taxes.

(Whether this is a good idea or not is debatable, but it’s the way things work right now and the fact that we subsidize truck shipping to the tune of a large amount of money is not widely known)

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The average American wants a big SUV/Truck
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This is not supported by good data, Car manufacturers are pushing to make bigger larger vehicles because they require very little additional manufacturing overhead over smaller vehicles and the manufacturers are able to sell them at higher prices.

What people want are Inexpensive vehicles, not necessarily larger ones. American car manufacturers have been actively suppressing cheaper smaller vehicles for their own benefit.

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Isn't "able to sell them at higher prices" a consequence of and an indicator of the demand by buyers?

Surely, if buyers didn't want these vehicles, makers couldn't sell them at high prices, right?

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That's where advertising comes in..
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> This is not supported by good data

It's supported by sales data.

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People buy SUV's because they want to avoid being injured in crashes (at the detriment of the other driver)
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This is definitely true. I do not currently know a single woman who DOESN'T drive an SUV and the answer I've heard more than once is just that they feel safer. The problem is, they're not wrong. But it's a spiraling problem - more big cars make the roads less safe which prompts more people to buy big cars...
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In Canada people also buy SUVs and trucks because they handle the bad winter weathers better.
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Yet per capita, US vehicle occupants are more likely to be injured in general while on the road than Europeans. Perhaps the driving standards are just far too different.
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Because US roads traffic control systems suck ALSO licenses are much easier to get, there is more of a tacit tolerance of drunk driving, and the lower rate of public transport makes more people forced to drive despite preferring not to, leading to less of a selective effect of drivers.

We've consequentially paved over the issues (no pun intended) via creating a socioeconomic hierarchy of insulation from traffic injuries. Giant SUV's have become the mainstay of the upwardly mobile 30s suburbanite, who is immunized from the road hazards, collisions and dangers that would cripple sedans.

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Two people crashing in big SUVs/trucks aren't really safer than two people crashing in smaller cars. As for the difference, my guess is the driving standards.
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Per capita isn’t meaningful, try per mile.
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In a discussion about city design, per capita matters.

That being said, EU is generally safer per km too.

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They also travel twice as much.
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Is that just because Americans spend a lot more time in their cars than Europeans do?
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No, per km Europeans are safer. Road design is safer, cars are safer.
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I'm not sure it is so simple. Some states have death rates in line with western/northern Europe (eg massachusetts has 4 deaths per billion km, similar to Germany), but road design and cars driven in massachusetts are highly similar to states with a larger death rate(south carolina, looking at you).
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A lot of EVs are heavier than SUVs... but don't let facts get in the way of your crusade.
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EVs tend to be about 10% heavier, like for like.
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Instead of assuming bad faith and resorting to insults, simply make the point. EVs can cause road damage too, yes.

I would reply that pound for pound EVs create far fewer issues in other categories than its weight-equivalent ICE vehicle, and that to an extent that weight is justified for the urban environment far more than a 2025 Chevy Duramax.

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"Forced"???
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