The Physics and Economics of Moving 44 Tonnes at 56mph(mikeayles.com) |
The Physics and Economics of Moving 44 Tonnes at 56mph(mikeayles.com) |
Braking distances, road damage (scales with the fourth power of axle weight), bridge limits, etc.
If the limit could safely and appropriately be 49 tons for diesel trucks right now, it probably would be.
THE ONE BEING OVERTAKEN COULD RELEASE THE THROTTTTTTLE...!!!
:)
And yet, electrical semis exist that come without 16 ton batteries. The fallacy here is that most of the diesel is used to heat the universe rather than move the truck. Truck engines are relatively efficient but it's still a combustion engine. EV trucks are now a reality.
Mercedes-Benz’s eActros 600, one of the flagship battery-electric long-haul trucks now in series production, uses *three 207 kWh LFP battery packs for a total of 621 kWh of installed capacity, and under realistic conditions can deliver about 500 km of range on a full charge with a 40-ton gross combination weight, with opportunity charging in driver breaks enabling well over 1 000 km of daily travel. That's 4-6 tons of battery, not 16.
Volvo Trucks’ current flagship, the FH Electric, has 360–540 kWh of batteries (four to six packs) and achieves up to ~300 km of range for typical heavy-duty operation, and its forthcoming FH Aero Electric long-haul variant is being announced with ~780 kWh battery capacity targeting ~600 km of range. That's around 3 tons of battery.
The weight goes at the cost of the useful load. Though the EU allows an extra 2 tons for new energy trucks. And of course a lot of trucks aren't fully loaded typically. Also, the weight limitations have a lot to do with safety issues related to diesel trucks and their brake systems that electrical trucks have much less. Regenerative braking and lots of torque at low speeds mean that they could move a lot more weight safely than currently allowed. And adding more axles to distribute the weight can address any road damage concerns.
With mandatory 45 minute breaks every 4.5 hours, trucks can just top up as needed. With normal truck driver hours that's 1 or 2 breaks in a working day. There's a growing amount of chargers all over Europe and these things routinely drive all over Europe from Scandinavia to Iberia to Balkans and everything in between. There are of course still many places where more/better chargers are needed but these ranges are usable and practical enough that you can get loads from A to B in most of Europe with only minimal delays relative to diesel trucks in terms of charging time losses. It's early days and charging infrastructure is rapidly being improved. But the point is, that electrical trucks work just fine today. There are no fundamental real load or distance limitations here. But of course more infrastructure is needed to scale.
Lighter batteries will make trucks slightly more efficient. But price and longevity matter much more. Sodium ion with its well over a million mile lifespan looks like it should revolutionize trucking over the next decade. LFP is commonly used today already. NMC is lighter but has a lower lifespan.
Are you happy for me to drop you an email to review a draft when I'm ready?
The article still never accounts for the fact that motors+inverters are ~2 tonnes lighter than an engine+transmission.
The driver gets there 5 minutes earlier in exchange for causing a 7-km tailback multiple times per day? That seems like exactly the kind of thing that should be regulated away: the truck in front is limited to 90 km/h, you're limited to 90 km/h, you should expect to travel in convoy with that truck even through manufacturing tolerances mean your limiter is actually set to 90.5.
If the 0.5 km/h is actually valuable to the trucking industry, they can invest in more precise limiters at scale.
From the article. Then goes on to show exactly how they're inconsiderate with maths. How they're not seeing it is baffling.
It's like when a big co says "now we care greatly about the environment" before going on to detail their plan for something that's laughably bad for it.
They see it. They just phrased the article that way because they don't want to catch hand wringing and hate comments from every idiot who does the exact same thing in their car with slightly different values for the variables outlined and without any of the physics/economics excuses to justify it.
Edit: I hope. I can't read minds, you may very well be right and they don't see it.
Yes, and the regulation should NOT be limiting passing or requiring the slower truck to brake
It should allow a "Push To Pass" button that allows a 10mph boost for enough seconds to make a pass in a reasonable amount of distance so as to not create problems for other traffic.
Current technology would allow these to be easily limited to X uses per hour/day and even geo-fence the usage for safe zones (use could even be limited to passing lanes so the truck being passed cannot start a drag race to stay ahead). They could even require connectivity and disable it in poor road conditions.
The real people being inconsiderate are not so much the truckers (particularly the slower trucker failing to yield and let the other one pass in a reasonable distance), as it is the regulators who created this mess.
This is regulated via "no overtaking by trucks" [1] signs on portions of road that are susceptible to formation of queues, or more dangerous road conditions.
P.S. To bundle some replies:
> but they only apply during busy hours
Don't remember ever seeing the time interval next to these signs. They are tied more to the location than the time. But that's not bad? The goal is to avoid the worst issues, not to force trucks to drive in an ordered line for 8h straight. Traffic lights also sometimes turn to intermittent yellow late in the night. Why spend a few minutes alone in the middle of the street for a red light?
> Does it still make sense for that to be "default allow?" Why doesn't the trucking industry lobby for every Truck Overtaking zone
The default should be the the one that applies most of the time. Today that's the "allow overtake". I'm allowed to very slowly overtake in my car. And I've seen this when I was driving right at the speed limit and someone else was overtaking at something like 1cm/s. It was painful to watch, at some point I just slowed down a bit to let him get in front and release the left lane.
If you ban truck overtakes and allow them only in specific zones, you'll quickly have kilometers long truck queues that never get drained. For an overtake that takes 1 min at 90km/h the trucks traveled 1500m. Many highways are 2 lanes so just one slow truck on the right lane and one slow car on the left lane screw the entire highway. Those costs go to you whether you're in your car or buying something those trucks deliver.
[1] https://media.gettyimages.com/id/1728143251/vector/no-overta...
Does it (still) make sense for this to be "default allow?" Why not have the trucking industry lobby for every Truck Overtaking zone, instead of making residents lobby for the opposite?
However, as with any traffic controls they're useless if they're not actually enforced. Which is a shame, because it'd be absolutely trivial to automate that detection with cameras.
https://trafficban.com/news.1590.html
There's an exception made for cases where there's a vehicle on the right lane going much slower than the speed limit for trucks.
The public broadly agrees that this move was beneficial, as the miniscule benefit of some trucks arriving 15min earlier overall was not worth slowing down everyone else, particularly light commercial vehicles.
People cut truckers a brake because due to the physics and rules they can only go so fast and only change speed so quickly.
The same cannot be said for the person camping the fast/passing lane because all the entering and exiting of the slow lane "is scary" or whatever. Their normal car can most definitely meet (and exceed) the expected norm for the lane they're traveling in.
I work in fleet fuel efficiency and wrote up the foundational mental model, covering why trucks weigh what they weigh, why they're all doing exactly 56mph, why diesel is so hard to replace, and why 1% fuel savings matters when you're burning 43,000 litres a year.
This is the first in a series, there's already a 2-part deep dive on hydrogen up as well. Tried to keep it accessible without dumbing it down.
I live in Latvia (in the EU) and see a significant part of our ARTICs on the roads go well past 90km/h daily. I presume their fleets do monitor the speed and alert the driver if speeding for a prolonged period of time but they are obviously not physically limited. Maybe the limits do come from the factory but get disabled? I really couldn't say.
A recent journalistic investigation uncovered a problem with the weight limit not being followed on a mass scale too. Specifically by our lumber industry whos drivers are incentivized to break the law. Even if you see a dangerous overloaded truck on the road and call the Police, it is likely no action will be taken because there only a couple of units in the country that are equipped to weigh a freight truck out in the field.
Sort of like the silly "boost buttons" on the Honda CR-Z [1] or the Elantra N [2], but just lifting the speed limiter for a bit...
[1] https://en.wikipedia.org/wiki/Honda_CR-Z#Powertrain
[2] https://en.wikipedia.org/wiki/Hyundai_Elantra#Elantra_N/Avan...
Lots of good info but it all feels a bit like it is being used to create a "just so story" to support whatever the current status quo is.
C=πD and all that.
Before around 1950x-1970x rail networks were more dense (at least in Europe) - any significant goods source/destination (like a warehouse, a factory e. t. c.) had a railway spur. Lots of rail tracks / spurs were abandoned /removed when it was widely believed that trucks are the future and railways are outdated.
If all these spurs were kept last mile problem would not be as bad for railways. Also electric trucks are well suited to solve this last mile problem.
> Distribution centres are built around motorway junctions (J24 of the M1, the Golden Triangle in the East Midlands) because that’s where road access is.
But they skip _why_ is that road access and motor junction there. It's there because the government decided building roads was something that was it's responsibility. I know this article is UK focused, but for the US if the government decided to build rails also, then they could put them in more convenient places. Instead they allow rail companies to decide which monopoly corridors the companies get to control.
The combination of higher efficiency, regenerative breaking, and some regulatory wiggle-room such as slightly higher allowable gross-weight (2000 lbs in the US, and 2000 kgs in the EU), together with reduced maintenance cost and time significantly affect the economics of trucking.
As regulatory frameworks price in more externalities of internal combustion engines, such as the climate and health effects of their emissions, burning diesel will no longer make economical sense. All road transport will end up being battery-electric. The declining cost of owning and operating electric vehicles compared to internal combustion ones will reach this point even without regulatory changes, just at a slower pace.
US gallons are 3.8l
As a naive non-trucker, I'm surprised to hear that the difference between the best and worst operator is this significant. I realize it's a bad look, and shows I thought this was a low-skill job, but I'll be honest and try to call out my own prejudice. It's cool that skill actually does have a large impact here.
Man, that's kindof scary -- if for some reason the truck legitimately needs to go faster (eg, escape a warzone, a flood, a wildfire), it cannot do so. I'm sure this was a calculated design decision, but on the surface I'd prefer if the speed was logged and then checked at regular intervals (perhaps with automated reader). That would also allow for easy updates to the limit, tighter restrictions in specific areas, etc. I wonder what all the factors going into this design decision were.
This is a tech site, just imagine what absolutely terrible things could be justified, 'just in case'
One thing I'd update is that early in the article you say that for switching from diesel to lithium-ion, "It's 16 tonnes of payload that disappears".
But then later you take engine efficiency into account and say it's "about 6.4 tonnes of battery".
So the claim that it would ever reduce payload by 16 tonnes seems incorrect, and not everyone is going to read both parts.
This misses the fact that the motor and transmission on an electric truck is lighter than the diesel. This doesn't completely negate the issue but it does help and is not mentioned.
The 15 liter diesel engine is about 3500 lbs and the transmission with many gears is another 700 lbs.
The Tesla Semi has 3 model S motors with single speed transmissions each one is about 300 lbs with inverter so there are at least 2-3000 lbs weight savings in the drivetrain to consider.
In the US Electric semis get an extra 2000 lbs payload allowance too too so they can be 82k lbs total rather than 80.
Let me paraphrase - a truck weighting 25 times more than a car burns only 4 times as much fuel per 100km at corresponding cruising speeds.
> At 0.25 kWh/kg, that’s still about 6.4 tonnes of battery — roughly 18 times heavier than the 350 kg diesel tank and fuel it replaces, and 6.4 tonnes of payload that disappears from every trip.
And how many tonnes of internal combustion engine, gearboxes and plumbing? It is not an insignificant matter
"UK speed limits for heavy vehicles are also more complex than most car drivers realise. Articulated trucks over 7.5 tonnes: 60 mph on dual carriageways, 50 mph on single carriageways, 56 mph (limiter) on motorways"
Not able to find a source that verifies that
But...speed limiters effectively limit all heavy vehicles to 56mph[1]
Note that speed limiter are mandatory above 3.5 tons, but the legal limits change at 7.5 tons.
[0]https://www.gov.uk/speed-limits [1]https://eptraining.co.uk/news/article/hgv-speed-restrictions...
Edit: Nope, despite the vehicles only being able to propel themselves to 90kmph, the speed limit is indeed 60mph (in England and Wales, Scotland is a more sensible 56mph)
Assuming my time and everyone else stuck behind them combined is far less valuable than the truck driver.
He even said the problem with trains is last mile. Last mile short haul trucks can be and are electric.
It's weird he laid the groundwork for this argument, but he isn't making this argument.
Fix the infrastructure issues that make transferring from rail to truck difficult. Yes, that's challenging and expensive. Guess what else is? The status quo, and the effects of climate change.
You could probably add a whole section of specifically learning to drive a car with trucks on the road to driver education programs and it would do wonders for traffic.
>Anti-idle ordinances exist in several US states and EU regulation is moving in this direction.
Yep, grab a sleeping bag or take your clothes off and use evaporation cooling on yourself. The good news is that car/van camping stuff can apply to trucking as well and that is fairly popular these days.
Another option is simply having places to sleep outside of the truck that are powered by solar/wind and don't cost anything to truckers, but that's only viable when we actually care about reducing emissions over profit.
>Every kilogram you add to the vehicle is a kilogram you can’t carry as freight.
You can save a bunch of weight by not having the sleeper cab if you can readily stop somewhere for a safe place to sleep. There's quite a bit of frontier savings you can do by externalizing costs of transporting stuff to other industries (aforementioned free hotel rooms) and getting tax payers to pay for it, which makes a ton of sense here since trucks are transporting all of the food we eat.
Talking about driver education, refrigerated trucks never get to turn off the engine until they unload the cargo. So it's not always for comfort.
> if you can readily stop somewhere for a safe place to sleep
That's the missing infrastructure. Drivers pull over to sleep when they hit their daily driving limit and in Europe most of the places to pull over are plain old parking lots maybe with some services like a gas station. Motels are relatively uncommon. I think losing some of the driving day and paying for a motel more than make up for the benefit of a lighter cab.
The refrigeration unit often runs on a separate unit powered by its own engine, not the engine powering the truck. Don’t get excited just yet, as those engines do not run clean. They do use less fuel than the truck’s engine, though.
The car's L/hr figure was wrong. At 45 mpg (imperial) and 70 mph cruise, a car burns ~7 L/hr, not 3. That makes the flow rate ratio ~4x, which is consistent with 5x per mile and the truck travelling 20% slower.
The ~3 L/hr I originally had is what you'd see as an average over a mixed driving cycle — ~30 mph mean across urban, suburban, and motorway. I was carelessly mixing the cars combined-cycle flow rate with the truck's cruise-only figure in the same row.
The truck doesn't have this problem because a long-haul artic genuinely spends most of its operating hours in that narrow 50-60 mph cruise band. "Average fuel burn rate" and "fuel burn rate at cruise" are nearly the same number. For a car they're very different, transient acceleration, idling in traffic, and low-speed urban driving all drag the average flow rate down well below the motorway figure.
But an RV is not a semi tractor-trailer setup. In fact, crosswind compensation is something I’ve only seen on RVs that don’t involve a trailer (Class A, Class C). And for a semi, how much is in the trailer? Seems a compensation system would need to know that.
> Every driver in the UK has experienced this. Most assume the truck driver is being inconsiderate.
But then go on to explain how that is exactly true. The truck driver is taking time from *all* drivers on "roughly 4.5 miles of dual carriageway", just so that they can end the day 5 miles ahead.
> The five minutes of inconvenience to you saves them meaningful time and money over the course of a day.
It's five minutes of inconvenience to *everyone* on that 4.5 mile stretch of highway that nets the truck 5 minutes (5 miles ahead at ~60 mph). That's a very selfish and inconsiderate outcome.
> Every kilogram you add to the vehicle is a kilogram you can’t carry as freight.
That is only relevant when hauling bulk loads, think ore, soil and the likes, or you're carrying a trailer full of IBC liquid containers. I worked in stage lighting stuff, our trailers were at least 3/4 foam by volume, they didn't even come close to maxing out their weight.
> A battery pack storing equivalent energy would weigh on the order of 16 tonnes at current lithium-ion energy densities.
You don't need to haul a fully equivalent battery. Drivers have to have their mandatory rest breaks of 30+15 minutes here in Germany - that's enough to charge 300-400km of range. Additionally, they can be charged at loading docks, provided the freight base or the customer have chargers set up.
> For a driver paid by the mile, or on a delivery schedule measured in minutes, that overtake is rational.
Payment by mileage is illegal in Germany, as a trucker you need to be paid by the hour and you need to be paid under German minimum wage law as long as you're physically on German roads. Trucker companies from Eastern Europe are infamous for evading that, but as our customs enforcement (who also do the road inspections for rest breaks and minimum wage) ramps up, it's getting better.
The remaining problem are the dispatchers, quite a few of them hand out routes to their drivers that are barely achievable when operating legally (i.e. trucks with working speed governors, drivers taking their rest breaks). Competition is fierce, there used to be talks about passing laws to force dispatchers to not give barely-legal orders but I'm not sure where these went following our government's collapse last year.
> An electric drivetrain achieves around 90%, so you only need roughly 1,600 kWh of battery capacity for equivalent range.
Yup, and most importantly, you mentioned regenerative braking cutting down on brake wear - but it's not just cutting down there, the truck can actually save a fair amount of energy as well, at least outside of highways where the truck is mostly just coasting along.
Trucks, given the right infrastructure, are also viable for running them electrically in the mid-range nowadays as a result.
I do think maybe with a hub & spoke model - big trucks move loads to hubs -- then smaller electrified trucks cover the less than 200 miles from hub to spoke. electrified smaller trucks and vans are already economical today.
you get to benefit from using diesel for long haul routes - while also - better economics on the electrified front i.e a hybrid model
This is why LTL shipments can be a significant fraction of just sending an entire container, and that's assuming they're still palletized.
That said, depending on the truck, there's fuses you can pull, ECU remaps and even for the older trucks with the magnetic sensor in the gearbox, the trick is/was to stick a magnet on the sensor (with a bit of string, so you can pull it off remotely if you get pulled over). All of these methods are becoming less feasible, as things like the aggregate wheel speed sensors used for ABS get used, you can't just fool one thing now.
As for the weight limit problem, that's a whole other rabbit hole!
Not every country is as thorough as Germany is in technical inspections, trucks from outside the EU don't need speed governors, and as long as you don't race your truck in Germany, France or Austria, chances are high no one will be bothered enough to pull your truck over for a detailed inspection on an examination wheel. Or you simply have two datalogger cards, that you swap out when going into one of these countries.
You cannot do that, because there will never be that many charging places around. Never. The situation is so bad now that there are barely enough places for trucks to get parking spots, let alone parking spots with electric charges. I'm talking about Europe, my brother is a truck driver (right now is on a ride to Morocco, he picked something up with his truck from Hungary), I know those stories about parking spots from him.
Your cargo may be reduced but your fuel costs will also be reduced. It’s quite a complicated calculation.
Are you hauling sand? Then you probably can’t spare a single kg of cargo limit. Doing LTL work? Then maybe you’re not totally filled anyways. It really depends. If you’re fine with a 35 ton limit you might be able to make good money with the fuel savings.
Assuming some amount of tesla over-hyping there, Tellus is doing 600kW chargers: https://chargedevs.com/features/inside-tellus-powers-600-kw-...
So _if_ your route had those, you could charge in somewhere around 1.25h. Not enough for break time, but you can imagine starting with, say, a 1.1MWh battery with one +500kWH boost mid-day being enough to get you to an overnight full recharge. Lots of "ifs" there, since you might not always be able to get full charge rate from the charger, might not time things perfectly, etc., but it doesn't seem completely out of scope for a few years from now.
(And who knows, perhaps tesla will come through with those megachargers. Seems more likely than, say, building an autonomous humanoid robot.)
And even if the company crunches the numbers and finds that tailgating saves a ton of fuel, they can't say "well ackshually guys, you can tailgate if it's another truck" to their drivers because society is full of dishonest jerks and we therefore can't have an adult discussion about just exactly how much diesel exhaust you have to save to make the marginal increase in semi trucks rear ending each other worth it.
Heck, the company probably can't even run that fuel vs braking analysis overtly because Pinto. Isn't progress great.
And as to passing, the closer the two vehicles are in speed the loooonger it takes one to pass the other. Unless you get down to an absurd accuracy, one driver will notice he's got a little bit of pace on the other guy and will try to pass. And even with 0.0001% accuracy and 100% uptime (not going to happen), there will still be passing issues as some trucks may have issues where they aren't quite up to speed, but just a few km/hr under, and you're right back to the long passes.
Either outlaw passing, or allow it to happen at a reasonable pace.
Nowadays you could apply a long-term trim using the GPS speed, including correcting for variations due to steering inputs and elevation.
Mandatory for new trucks and grandfather old ones, like how most new vehicle standards are adopted.
And you're right, it does seem that the systems are integrated. For example, Mercedes' system for the Sprinter applies the brakes on one side to compensate. Seems like something would need to tie into the CAN bus to pull that off. Not that aftermarket couldn't do the same, but is that functionality even available on a 43' pusher diesel?
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Which logs that the card has been swapped.
So, again, I very much doubt that there's a mass scale, country-level, tachograph fraud happening in Baltic states without anyone else noticing.
And having been part of EU business that does trucking, police REGULARLY pull over trucks for tachograph inspections (including rest and speeding) even in southern and eastern europe. Any truck business owner would be rather insane to risk the fines tachograph fraud gives at any consistent rate.
Do companies and drivers try to break the law? Yeah, I believe that. Do trucks systemically, constantly drive above speed limit in Baltic states and noone is checking that? BS.
Taking their foot off the gas for a second only hurts them
