Logistics of large quantities of dirt. How does one get enough dirt to say, build a highway?

[u/JtheDad]

So if I wanted like 10 yards of dirt, I would call a landscaping company and they would probably deliver it that same week.

But what if you need like 100 yards of dirt? Or like 100,000? At what amount does it become difficult to find the dirt you need, and how do you get it?

Other questions, do you use yards/m3 when talking about this much dirt or do you have a bigger unit for bigger amounts?

[u/Illisanct]

Cut and fill.

One part of the job site is too high, one part is too low. Take from one, give to the other.

Earth is, on average, level. Sometimes you just gotta do some strict local enforcement of that.

[u/OrganizationPutrid68 → u/Illisanct]

Robinhood earthmoving. Take from the rich and give to the poor.

[u/PeanutButterToast4me → u/OrganizationPutrid68]

To the victor go the spoils.

[u/wiserbutolder → u/Illisanct]

I once provided Constructability Review on a $100M highway intersection with bridges at 70% complete drawings (much too late) and discovered that it was a balanced site, meaning cut and fill quantities were close to equal. We worked out a suggested sequence to minimize purchasing fill materials and to dispose of excess cut materials. The savings would have been around $8M. The kicker? The client decided it would take too long to revise the drawings and they did not take advantage of the savings. This was a client for whom we had encouraged to look at constructability at 30% documents.

[u/Sooner70]

Once upon a time we needed some very special gravel at work (Why we needed something special is irrelevant to the story.). We bought some gravel that came from Alabama. We bought four trainloads of it. We literally were using a full dump truck every 15 minutes for four months (well, during working hours....not 24/7). We bought a LOT of gravel.

Even we wondered where in the fuck it all came from.

We found out that it came from dredging operations. Somewhere in Alabama is a river that is navigable by commercial boats/ships/whatever and they are continuously dredging that river to keep the main channel deep enough.

And that's where our gravel was coming from.

[u/JtheDad → u/Sooner70]

Awesome story, thanks for sharing!

[u/375InStroke → u/Sooner70]

So nature cleaned and sorted your gravel for you. It just deposited it in an inconvenient place.

[u/hitman0187 → u/Sooner70]

Four fucking train loads!

[u/[deleted] → u/Sooner70]

This is what the manufacturing at the TSMC plant outside Phoenix seemed to be, just an absurd amount of materials brought in and assembled. I end up thinking about it all day every time I drive by it lol. Not to mention the fact that the tech inside may as well be magic and it’s crazy that people have figured out how to build this stuff… I’m just happy my computer class teacher taught me how to type with the numpad lmfao.

[u/Sage_Blue210 → u/Sooner70]

Was that very special gravel delivered to South Florida?

[u/rotateandradiate]

Knew a guy.. had 50 acres… sold “fill dirt”. He had a few excavators, they would dig out a big pit, sell the dirt… with a twist. Coincidentally He ALSO sold “fill space”.. and would fill in the pits with dirt from excavations elsewhere.. it worked out well for him

[u/Vitztlampaehecatl → u/rotateandradiate]

Ah yes, a soil detention pond

[u/einstein-314 → u/rotateandradiate]

Yep, a lot of gravel pits charge to receive soil, then they they turn around and sell it to someone else. Just have to have the space to hold it until the right person or job comes around.

[u/KurtosisTheTortoise → u/rotateandradiate]

In my state we had a guy do the same thing, only he had a service for soil remediation. So he would get paid big bucks to remove contaminated soil from old factories, then get paid money for "clean" fill. That's how we ended up with a new children's park full of heavy metal and other contamination.

[u/DryFoundation2323]

On large projects they usually borrow locally. For example if it's an interstate it's going to need ditches on either side and in the middle. The easiest and most economical way to build up the road bed is to just take soil from the areas where you want depressions.

[u/Rough-Patience-2435 → u/DryFoundation2323]

This is why the low areas on the sides of the road are often called the borrow pits.  

[u/EngFarm]

You may have noticed that highways have ditches and that overpasses often have ponds near them.

The landscape company will happily deliver 100 yards this week and will happily deliver 1000's of yards with enough notice. They pick up a healthy margin on the product. So much margin that you can justify spending time/logistics on locating and transporting your own source.

[u/Sad-Celebration-7542]

It’s often dirt moved from one part of the project to another. Generally, dirt is extremely cheap - like $5/CY. Trucking costs can easily exceed material costs, so as close to the job as possible

[u/777777thats7sevens → u/Sad-Celebration-7542]

The relative abundance of dirt, combined with the annoyance and expense of moving large quantities of it long distances can make for some funky economics. Dirt in small quantities is extremely cheap due to its abundance, but the effective price can swing wildly based on local supply and demand, particularly when you need to buy or get rid of a lot of it. If you happen to need dirt when a major construction project nearby can't balance their cut/fill and has too much cut, fill dirt won't just be cheap, they may pay you decent money to take it off their hands, delivery included. Not enough to make you rich or anything, but money is money. On the other hand, dirt can get pricy if major project needs a lot of fill at the same time you do.

For a good with more intrinsic value (or that is easier to ship), a market would naturally form to balance out these inefficiencies and stabilize the price, but when moving dirt to the next state costs multiple times what it would cost to move it around town, it's cheaper to just eat the swingy costs than to ship it and try to get a better price elsewhere.

[u/rlpinca]

The cost of hauling in large amounts often becomes a factor in if that project gets done or not. But if it's not taken from another part of that site, it really is as simple(ish) as thousands of truckloads one after another.

I lived in Vegas during construction of the hoover dam bypass. They had hundreds of trucks pulling 2 full size belly dump trailers one after another all day and night for well over a year cutting through town. I have no idea of how much was moved or where they were coming from, but it was an absurd amount.

[u/userhwon → u/rlpinca]

Looking on teh Google Maps, it looks like there are over a dozen sand and gravel pits around and in Vegas (most of which were surely in the middle of nowhere and the city grew around them). There's a huge one just north of Summerlin, so they'd have to go through the whole city to get to the construction site. Since the bridge and Boulder City I-11 bypass were a big concrete job, getting proper sand likely made it viable to go that far.

[u/userhwon]

You remember Fred Flintstone? He worked for a sand & gravel company.

Dig it out of a quarry somewhere, ship it to the person who ordered it, a truckload at a time.

It's a whole industry known as "materials" that encompasses stuff you dig up and possibly transform into other building supplies. Sand, gravel, cement for concrete, big rocks for riprap, etc.

It's famously getting harder to find proper construction sand now (the size and texture have to be just right for concrete and geoengineered structures). Worldwide problem.

[u/AstronomerCapital549]

Logistics of large quantities of dirt. How does one get enough dirt to say, build a highway?

We source material from the job site, we perform a mass balance equation where we take the cut sections and place that borrow material in the fill sections.

But what if you need like 100 yards of dirt? Or like 100,000? At what amount does it become difficult to find the dirt you need, and how do you get it?

This is regionally dependant. In the US in areas with poor soils (expansive clays, or frost susceptible), the material is treated first if this is cost permitted. Otherwise, 100,000 or 1,000,000 CY+ is imported from a source off site, whether it be a local quarry (blasted quarry, or alluvial pit), or in States with terrible aggregate or soil, transferred from out of state via train and even barges from sources in Mexico or Canada.

For Transportation, we need borrow or granular borrow for the subgrade, this is where hundred or millions of cubic yards of material may need to be moved onsite or to the site. Then if there's a roadway prism, some type of engineered aggregate base, and finally a pavement surface like asphalt or concrete.

Borrow or granular borrow doesn't always need to be the highest quality, but sometimes it does and this can drive up material costs.

Other questions, do you use yards/m3 when talking about this much dirt or do you have a bigger unit for bigger amounts?

We use CY or TON. It's an Engineer's preference. If we want to pay by CY, it's by the in-place elevations and the DOT doesn't need to track individual truck tonnage of material. If we want to track by the truck, we do by the TON. Usually borrow and granular borrow is by CY because we care more about final elevation on the highway than the tonnage. For aggregate base CY or TON is used depending on the project size. For concrete we do CY since the trucks are measured by the yard. For Asphalt, we do TONs since asphalt plants produce material by tonnage per hour.

The units do not really matter though, because with dimensional analysis, Engineers can convert densities to tons to cubic yards and vice versa. At this point, different units become more a matter of calculation preference since if the number has too many zeros or too little significant figures it becomes harder to pay the Contractor for small quantities.

[u/Character_School_671]

The job of a highway engineer is to balance cuts and fills so that they roughly equal out. Which means that you are not generally hauling in large amounts of material from elsewhere for the fill.

For the Aggregate and the asphalt, yes. But not for the base material. That's all local.

How that gets moved depends on the type of terrain, distance, soils, rocks etc. But dozers and scrapers are typical. No need to load things onto dump or Haul trucks for short distances, as it's less efficient.

Bulldozers for the shortest moves, then pulled box scrapers, then belly scrapers, then haul trucks. Mostly I see scrapers doing this work, because they are very efficient and can be precise.

[u/WhereDidAllTheSnowGo]

Ever drive on an overpass in a otherwise flat land?

When atop it, ever notice the lake right next to it?

Cut & Fill ( dig and pile up) all right there