The 2-D Three Body Problem

January 10, 2024 2:11 AM

If we must have road-haulage, let it be efficient. One tractor with two trailers is more planet-kind than two tractors with one trailer each. Simple enough if the rig is going forward. Not so easy reversing a B-train round a corner into a narrow dock. This is the moment I knew it would work [8m50s].

I live rural, where kids learn to back a farm-tractor and trailer through a gateway before they leave primary school. Dirt Farmer Jay tells us It's all in the thumbs [9m15s]. Learning with Tonka Toys on a table is safer than out on the road. When learning how to back a B-double Don’t drive above yer own ability and don’t be a goose [9m40s]; and indeed Keep the rubber side down [8m50s].

Keeping your A-trains and B-trains [B-double, tandem rig] straight in your head. Trailers are 53 ft = 16 m long because 40 ft shipping container.

MetaPrev American Truck Simulator.

posted by BobTheScientist (30 comments total)

When was this skill first developed?

I would guess as far back as ox/mule/horse-carts, but I don't know for sure. Has it been passed down since like, Assyrian times? I would assume it's almost as old as the wheel, but maybe backing up isn't really a big thing before motor engines?

These people are wizards, I stopped playing ETS because I couldn't get the hang of this. Farming Simulator at least has more open space. Doing it IRL seems petrifying.
posted by Audreynachrome at 3:42 AM on January 10

The skill of backing into a tight space pre-dates marriage, for certain.
posted by PareidoliaticBoy at 4:11 AM on January 10

There is a downside to double trailers - they are much rougher on the roads - at least that’s one explanation for Michigan’s crappy roads I have heard
posted by pyramid termite at 5:36 AM on January 10

I can back up a regular trailer, but this seems insane. Reminded me that I have a copy of ETS, maybe I'll give it a go.
posted by Harald74 at 5:37 AM on January 10

Why not have a couple tractors just at the terminals for switching to a one tractor per trailer setup for backing up? (Aside from that the skill involved is impressive.) Get the advantages of both setups where you most need them. I am quite possibly wrong, since I don’t know much about this (yeah, aside from playing with multi-cat toy trains that weren’t on tracks, this approximating a multi-trailer setup, as a kid some decades ago), but I would think the space needed for an unhitching the second trailer and attaching it to one of the terminal’s tractors for terminal manoeuvering would be equivalent to or less than the space needed to back up a double trailer?
posted by eviemath at 5:49 AM on January 10

Every time Grumpybearbride and I go to Michigan we encounter those double-trailer FedEx trucks, and without fail they are weeble-wobbling around in a perilous fashion. 0/10 do not like.
posted by grumpybear69 at 5:52 AM on January 10 [1 favorite]

Why not have a couple tractors just at the terminals for switching

The video appears to be of the trucker delivering directly to a customer, a small hardware store with poor loading/unloading space, and even less likely to have the means of moving a semi trailer on its own. If he was delivering to a terminal, there'd be a path which wouldn't require any backing up at all.
posted by AzraelBrown at 6:29 AM on January 10

I watched someone back a double trailer down a long, narrow, and bendy driveway to a loading dock, and they did it incredibly smoothly and on the first try. They deserved a medal for that.

I can, with some trial and error, more or less back up a single small trailer. I used to work at a place where a lot of the guys had their CDLs and had spent time as semi truck drivers. They made trailer backing look incredibly easy, always making moves two steps ahead that ended up with the trailer in the exact right spot.
posted by Dip Flash at 6:35 AM on January 10 [2 favorites]

(missed my edit window, but there probably would be backing up, it'd be far more manageable and kept to a minimum than what's in the first video)
posted by AzraelBrown at 6:36 AM on January 10

My dad drove semis in the city for 25 years. His ability to back up any manner of trailer with any manner of vehicle was always awe-inspiring to me.
posted by adoarns at 7:41 AM on January 10 [3 favorites]

There is a downside to double trailers - they are much rougher on the roads

Road damage is proportional to the fourth power of axle loading. The same load carried in a double, especially an A train, does much less road damage than that load carried in a single trailer.
posted by Mitheral at 7:54 AM on January 10 [1 favorite]

Why not have a couple tractors just at the terminals for switching to a one tractor per trailer setup for backing up?
Indeed that's effectively the final bit of advice from The Master of Don’t Be a Goose . . . to side-step the head-shaking derision of 22 bludgers having smoko outside of the place where you have to make a tricky delivery: leave the pup-trailer [technical term] down the street; back up the main trailer, unload; leave that down the street; rinse, repeat.
posted by BobTheScientist at 7:59 AM on January 10

Some guys can turn it on a dime or turn it right downtown,
But I need 40 acres to turn this rig around.

--The Willis Brothers, 1964
posted by Pickman's Next Top Model at 8:07 AM on January 10 [1 favorite]

Indeed that's effectively the final bit of advice from The Master of Don’t Be a Goose . . . to side-step the head-shaking derision of 22 bludgers having smoko outside of the place where you have to make a tricky delivery: leave the pup-trailer [technical term] down the street; back up the main trailer, unload; leave that down the street; rinse, repeat.

I see people doing this every so often. But disconnecting/reconnecting/disconnecting/etc. is slower than simply backing in a double trailer rig, assuming the space is possible and you have the skill. So you would avoid derision and frustration, but you are spending longer in the load/unload process, which is usually unpaid time for truck drivers (who typically get paid only for moving mileage).
posted by Dip Flash at 8:16 AM on January 10 [1 favorite]

Look, I hate to be the one to say it, but... you know who's really good at calculating angles and equations of motion? You know who can have accurate eyes everywhere at once, instead of scowling at a beat-up rear view mirror? You know who can measure the position and speed of every part of this complex moving system, instantly? THAT'S RIGHT! IT'S YOUR FRIEND THE COMPUTER!

This sort of complex, low-speed, human-supervised maneuver is exactly what driving assistance systems (let's please not call them self-driving cars anymore, okay? deal? deal) are totally badass at. Please, please, let the computer do the work here. That guy probably burned through like a quarter gallon of fuel dragging that truck forward and backwards half a dozen times, and he was good at it. Efficiency is important. We do not need to John Henry this shit. This is the trucking equivalent of computing a complex spreadsheet. Let the computers do it.
posted by phooky at 8:53 AM on January 10 [5 favorites]

Not sure if it is still allowed, but at least down in Oregon, they used to allow triple trailers. Crazy to pass on a rainy night on I-5.
posted by Windopaene at 9:11 AM on January 10 [2 favorites]

I suppose it shouldn't surprise me that the motorcar-dominant US would develop a system whereby an exhausted motorist needs to balance two brooms atop a third one just to deliver a couple flatcars of goods. The fact that this task or skill is required at all is absolutely absurd.
posted by rum-soaked space hobo at 9:41 AM on January 10

I was on the farm when I was young. The foreman could back two wagons full of hay into a long storage barn with inches to spare on the door frame. I wouldn't believe it if I didn't see it with my own eyes.
posted by ovvl at 9:47 AM on January 10 [5 favorites]

Well, last week, I had to tow a UHaul trailer about 3600km - it was only the 2nd time in my life that I drove a trailer any distance. The first time I towed a trailer was a quarter or less distance and ended up in 'disaster'... it was a 27-foot RV rental, and I drove perfectly to the campground a province away and back without incident, only to hook the side of it on another trailer at the rental facility when I was returning it. (Narrator-voice... "Did he originally decline the insurance, assuming his CAA insurance would cover it?" "Why yes... yes he did...")

Needless to say, this time I was extra nervous. Planned all my stops with pull-through parking in mind. Only had to back it up twice - and it went ok. But... oh the gas... soooo much fuel... and my vehicle is only a 6-cylinder, so... I was giving it "premium" to keep it happy. Never above 90kph, as you could just watch the fuel gauge drop in real time...

But, outside of some fog from Calgary to Medicine Hat, then freezing rain outside of Portage la Prairie, the weather held and the trip and passengers and pets all got home ok.

(I have immense respect for truckers and people who can handle single trailers - let along doubles... I couldn't even imagine...)
posted by rozcakj at 11:33 AM on January 10

Lots of States, including Oregon, allow triples (3 short trailers). Rocky mountain doubles (one long and one short trailer) or turn pike doubles (two long trailers) are also options [pdf] in much of the west both US and Canada. Passing, or worse being passed by, a turnpike double being hauled by a conventional cab with a sleeper is quite the experience.
posted by Mitheral at 12:01 PM on January 10

I suppose it shouldn't surprise me that the motorcar-dominant US would develop a system whereby an exhausted motorist needs to balance two brooms atop a third one just to deliver a couple flatcars of goods. The fact that this task or skill is required at all is absolutely absurd.

Is this where someone needs to link the statistics of how much more freight is moved by railroad in the US, vs Europe where freight is almost entirely moved by road?

For serious examples of semis pulling multiple trailers, the Australian "road trains" are the biggest I've seen.
posted by Dip Flash at 12:11 PM on January 10 [1 favorite]

I84 Idaho speed limit for trucks is 70 MPH, which effectively means that if they can do 75, they will. Doubles and triples, weaving down the interstate with a 45 mph sidewind.
Fun times, you betcha.
posted by BlueHorse at 12:20 PM on January 10 [1 favorite]

Is this where someone needs to link the statistics of how much more freight is moved by railroad in the US, vs Europe where freight is almost entirely moved by road?

US domestic freight: 64% truck, 9.7% rail, 4.2% water

EU freight: 67.9% water (maritime), 24.6% truck, 5.4% rail
posted by grumpybear69 at 1:33 PM on January 10 [2 favorites]

I stand corrected, my memory of looking at those statistics a while back was quite different than those numbers.
posted by Dip Flash at 1:41 PM on January 10 [1 favorite]

It would take me a week to back up a truck like that... one day to back up the truck and six days to repair all the damage.
posted by Multicellular Exothermic at 1:42 PM on January 10 [1 favorite]

I stand corrected, my memory of looking at those statistics a while back was quite different than those numbers.

Had I not just read a whole thread on X about the prevalence of maritime shipping in the EU, I would have taken your comment at face value. It really is surprising! There's also the fact that the Freight / Passenger ratios for rail in the US and EU are inverted.
posted by grumpybear69 at 1:47 PM on January 10

To be clear, that EU freight: 67.9% water (maritime) total that Eurostat publishes is for ton-kilometres of freight moved through a country or its Exclusive Economic Zone, so for example, if you have the Ever Given sailing from Malaysia to The Netherlands with 100,000 tons of goods, then it sails from the Suez Canal into the Mediterranean, through Egypt's zone, then, say, 50km through Cyprus's EEZ, so 5 million ton-km, 500km across Greece's EEZ adding 50 million ton-km to Greece's total, and so on past Malta, Italy, Spain, Portugal, Spain, France and Belgium, until it arrives in The Netherlands.

I would guess intra-EU maritime freight is around twice that that's carried on the inland waterways, but that's just a guess. The Baltic sea ferries are important, but so also is the Great Lakes shipping industry to North America.

Anyway, this is by the by. Europe is definitely a roadfreight continent compared to the US's railfreight continent, hence Europe has the powerful sophisticated trucks, with the automatic gears and the manoeuvrability and visibility.
posted by ambrosen at 3:53 PM on January 10

> go to Michigan we encounter those double-trailer FedEx trucks, and without fail they are weeble-wobbling around in a perilous fashion

The FedEx units are A-trains, quite different (and worse than) the B-train setup. Smart Trucking explains it here, including the reason they wibble-wobble all over the road in a dangerous manner, whereas the B-train doesn't do so.

For those without the patience to watch: The A-train setup typically has just one axle in front and one in back. And the one in front typically does not have brakes. Loaders invariably pile all the weight in the front of the trailer (to ensure they can fit all the freight in) and taper off towards the back. So those rear pup trailers have two wobbly swivel points near the front, no brakes there, the majority of the weight in the pup trailer placed there, and the rear of the trailer where the brakes are, is very lightly weighted.

You can see how that adds up to wibble-wobbling all over the road - especially in poor conditions.

FWIW the A-train setup was banned in Canada due to the poor safety record - thanks to all the factors I outlined above. But it survived in the U.S. because FedEx & UPS put their thumbs on the scale hard when the safety was evaluated. (All per the linked video - I know exactly zero about this personally.)

In addition, the B-train is exponentially easier to back up - it has one less swivel point than the A-train. The A-train has three - and two of them very close together at the front of the pup trailer - whereas the B-train has just two.
posted by flug at 4:05 PM on January 10

The Chicago produce market's loading docks run along the front of buildings that are maybe three or four hundred yards long. When I drove cross country, box trailers were 45 feet long; with the tractor, the outfit was maybe 60 +/- feet long. Some spaces in that marked left only a few inches between trucks; the space between the buildings was maybe 80 feet. This meant the driver had to know how to jackknife the rig without hitting the rigs on his blind side while putting the trailer straight into the space, then rotating the cab perfectly in line with the trailer to get it against the dock.

Over-the-road drivers were notoriously poor at backing into close spaces, so some of the day workers hiring out as lumpers also became experts at hitting those slots the first time--they charged $20 to do this for drivers who didn't feel like they could handle it without clipping another rig or burning out their clutch.

The closest fits I had to make were at a dock in Portland, Oregon. The docks were in a brick building about 75 or 80 feet between the dock and the next building. I had to fit the back of the trailer square with the dock, put it straight back, and park it with the tractor at precisely right angles to the trailer so that other trucks could pass through while I was being unloaded. Fortunately, enough space between the trailers existed to get the trailer out without taking pieces of the next rig with me.

I drove a set of doubles when I hauled grapes to Gallo and Roma in Fresno, California. One of the other drivers knew how to back up a set of doubles. But he was a wizard sent down by the gods to keep the rest of us humble.

TANS truck driver story: I arrived at the dock at the Chicago produce market with 43,000 pounds of mixed produce. After opening and pinning my trailer doors back, I backed into the assigned slot, then hopped up on the pier and handed my manifest to the dock foreman, who sent three lumpers to move the boxes from the trailer onto pallets brought by the forklift driver. All was well for about ten minutes.

Then, I heard a commotion a few dozen yards down the dock. A handful of people were vigorously brawling--seriously flinging motherfuckers, fists, and kicks at one another. The dock foreman pulled open one side of his vest, reaching for a pistol he kept in a shoulder holster; he mumbled a heartfelt Oh shit when he realized the holster was empty.

I was done; I hopped off the dock, climbed into the cab, and left the dock, figuring I'd worry about closing the trailer doors later. When I pulled out onto the causeway toward the front gate, I saw a security cop car headed in my direction. I stopped to let them by, and the driver leaned out his window and asked what was happening. I yelled down at him that they were rioting in building nine (or whatever the building was). He yelled thanks back at me, and I took off for the gate. In my mirror, I saw him turn around. He beat me to the front gate by 400 yards.

My co-driver (the truck's owner) was awake by this time. She asked me what was going on, and I told her. When we left the gate, I stopped and went back to shut the trailer doors. I got one of them unpinned and closed when I heard someone in the front of the trailer yell hold on, hold on. All three lumpers had scurried across the top of the load and were hidingn under the reefer unit.
posted by mule98J at 4:44 PM on January 10 [3 favorites]

I had to look this up:
lumper: laborer who unloads cargo
reefer unit: refrigeration unit on a truck--usually at the top/front of the trailer over the cabin

posted by eye of newt at 1:00 AM on January 11