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Author Topic: Maybe Trucks Don't Cause That Much Road Wear?  (Read 1708 times)

kernals12

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Maybe Trucks Don't Cause That Much Road Wear?
« on: April 28, 2022, 10:36:26 PM »

The American Truck Association has a refutation for the claim that one truck causes as much road wear as 10,000 cars.

They say that the 1962 study that claims originates from was taken out of context, and that the experiment used intentionally under-designed pavement to test how much weight roads could take and they quote a 1979 study by the National Academy of Sciences that concurs.

Your first thought is to dismiss this as trucking industry propaganda, but they make a good point: why do parkways that only allow passenger cars suffer from potholes if trucks do so much damage? For that matter, the asphalt sidewalks near where I live are in poor shape and it's certainly not because of traffic.
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Duke87

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #1 on: April 28, 2022, 11:23:24 PM »

why do parkways that only allow passenger cars suffer from potholes if trucks do so much damage? For that matter, the asphalt sidewalks near where I live are in poor shape and it's certainly not because of traffic.

Because the formation of potholes is driven primarily by freeze-thaw cycles, not by vehicle loading.

And pavement on parkways does last longer than pavement on freeways... if it is built to the same specs. Often, however, parkway pavement is thinner/weaker specifically because the lack of trucks means it doesn't need to be as tough.

Your local sidewalk, meanwhile, is probably just an inch or two of asphalt thrown directly on the ground with no subgrade or anything, i.e. far less robust than what an actual road is typically paved with - so of course it falls apart more easily in spite of not having to carry significant weight.
« Last Edit: April 28, 2022, 11:26:24 PM by Duke87 »
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Rothman

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #2 on: April 28, 2022, 11:38:26 PM »

At least I'm told that it's a pretty proven principle by the Highway Data Services Bureau at NYSDOT that pavement that is not subject to semis lasts much, much longer than pavement that is.  I believe their analysis of NYSDOT's historical pavement conditions over a truck industry group's cursory take.
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kernals12

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #3 on: April 29, 2022, 12:02:25 AM »

At least I'm told that it's a pretty proven principle by the Highway Data Services Bureau at NYSDOT that pavement that is not subject to semis lasts much, much longer than pavement that is.  I believe their analysis of NYSDOT's historical pavement conditions over a truck industry group's cursory take.

But is that due to semis that are below weight restrictions?
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Rothman

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #4 on: April 29, 2022, 12:22:43 AM »



At least I'm told that it's a pretty proven principle by the Highway Data Services Bureau at NYSDOT that pavement that is not subject to semis lasts much, much longer than pavement that is.  I believe their analysis of NYSDOT's historical pavement conditions over a truck industry group's cursory take.

But is that due to semis that are below weight restrictions?

I'd think it was pretty much based upon % truck traffic in their counts.
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kalvado

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #5 on: April 29, 2022, 08:27:26 AM »

At least I'm told that it's a pretty proven principle by the Highway Data Services Bureau at NYSDOT that pavement that is not subject to semis lasts much, much longer than pavement that is.  I believe their analysis of NYSDOT's historical pavement conditions over a truck industry group's cursory take.

But is that due to semis that are below weight restrictions?
That historical and disputed assessment is that damage goes as 4th power of axle load.
In other words, 10% overweight causes 50% more damage, 10% underweight is 35% less damage.
It is a matter of where to draw the line and  balance cost of extra traffic - including extra weight and cost of a truck cab, extra driver, and extra pavement to accommodate more vehicles vs still existing damage from weather patterns.
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vdeane

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #6 on: April 29, 2022, 12:39:08 PM »

Your local sidewalk, meanwhile, is probably just an inch or two of asphalt thrown directly on the ground with no subgrade or anything, i.e. far less robust than what an actual road is typically paved with - so of course it falls apart more easily in spite of not having to carry significant weight.
Plus most asphalt sidewalk (true sidewalk, not paths) that I've seen is just an inch or two slapped on already-deteriorated concrete because that's cheaper than replacing the concrete (the other one I can think of was a temporary one between two phases of a construction project).  It tends not to hold up well.
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triplemultiplex

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #7 on: May 01, 2022, 02:41:50 PM »

The trucking industry is wrong.  You don't even need a complicated study to understand that pavement wears out faster under heavy truck traffic.  Simply drive around this country.  Highways with more trucks need more maintenance that similar highways in the same areas with fewer trucks.

Also, if trucks didn't cause more wear and tear, then why would the National Center for Asphalt Technology test various mixes of asphalts by subjecting them to a barrage of trucks?
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kalvado

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #8 on: May 01, 2022, 02:56:09 PM »

The trucking industry is wrong.  You don't even need a complicated study to understand that pavement wears out faster under heavy truck traffic.  Simply drive around this country.  Highways with more trucks need more maintenance that similar highways in the same areas with fewer trucks.

Also, if trucks didn't cause more wear and tear, then why would the National Center for Asphalt Technology test various mixes of asphalts by subjecting them to a barrage of trucks?
IMHO the question is more about "fair" allocation of expenses. Trucks may cause significant west, but 5hey are more tolerant to defects. Bicycles and motorcycles cause almost no wear, but are way more sensitive to defects, including weather related.  Cars are 8n between, but they are numerous and require a lot of pavement.
Weight to the 4th power basically means that a single loaded 18-wheeler causes as much wear as entire car traffic of the day. But then weather is still going to be the dominant wear for 1 truck a day situation. Should weather related wear be allocated 50:50 in this scenario, for example?
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J N Winkler

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #9 on: May 01, 2022, 03:05:43 PM »

That historical and disputed assessment is that damage goes as 4th power of axle load.

In other words, 10% overweight causes 50% more damage, 10% underweight is 35% less damage.

It is a matter of where to draw the line and  balance cost of extra traffic - including extra weight and cost of a truck cab, extra driver, and extra pavement to accommodate more vehicles vs still existing damage from weather patterns.

There has been research since the AASHO Road Test that suggests the actual power law relationship can vary to some degree based on various factors such as subgrade type and degree of compaction, pavement type/thickness/service history, extent of usage by overweight vehicles, and so on--but the interval I've read of runs from power of three to power of five.

I think it's important to realize (as you suggest) that, whatever the specifics are for a given combination of subgrade, pavement, and usage pattern, it is important to understand the costs of catering to truck traffic and make appropriate provision, whether that involves revising engineering standards for new construction/full-depth reconstruction or somehow shaping the truck traffic through restrictions (e.g., banning trucks on certain roads, taking into account the degree to which such bans will be observed) or economic regulation (e.g., higher taxes or more stringent licensing for trucking-related activities).  It is a multi-parameter problem of optimizing consumer's surplus.

The ATA, being a trucking industry lobbyist, is going to be for trucks über alles, and thus has a vested interest in pointing out the fourth-power law does not hold with exactitude in all cases.
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kernals12

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #10 on: May 01, 2022, 10:15:57 PM »

The trucking industry is wrong.  You don't even need a complicated study to understand that pavement wears out faster under heavy truck traffic.  Simply drive around this country.  Highways with more trucks need more maintenance that similar highways in the same areas with fewer trucks.

Also, if trucks didn't cause more wear and tear, then why would the National Center for Asphalt Technology test various mixes of asphalts by subjecting them to a barrage of trucks?

But the question is does one truck really cause as much road wear as 10,000 cars?
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kalvado

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #11 on: May 02, 2022, 08:29:57 AM »

The trucking industry is wrong.  You don't even need a complicated study to understand that pavement wears out faster under heavy truck traffic.  Simply drive around this country.  Highways with more trucks need more maintenance that similar highways in the same areas with fewer trucks.

Also, if trucks didn't cause more wear and tear, then why would the National Center for Asphalt Technology test various mixes of asphalts by subjecting them to a barrage of trucks?

But the question is does one truck really cause as much road wear as 10,000 cars?
...and if they do, wouldn't weather still be a dominant factor?
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MikieTimT

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Re: Maybe Trucks Don't Cause That Much Road Wear?
« Reply #12 on: May 02, 2022, 03:46:37 PM »

Many asphalt intersections on roads with heavy truck traffic with traffic lights in my area disprove this theory.  There's a fair number that have standing water for dozens of feet in moderate to heavy rain near the intersection due to the weight of braking and accelerating semis.  Travel most 2 lanes in south Arkansas where there's a great many logging trucks and you'll find it difficult not to hydroplane in rainy weather.
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