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The Physics and Economics of Moving 44 Tonnes at 56mph

mikeayles.com

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Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#101

Post by spaqin »

yabones wrote: post #82

Maybe they should give the trucks a "turbo boost" button that lets them increase speed by something like 5 KM/hr for 120s every 30 minutes. Just enough to allow truck drivers to pass now and then without causing these types of log-jams on the highways, without causing safety problems. I'm sure there's a more correct combination of speeds and times than this. Sort of like the silly "boost buttons" on the Honda CR-Z [1…

The incentive for the drivers would be to press the button every 30min, regardless of actual overtaking need. And when overtaking has to be done, the button would probably be in cooldown, solving nothing.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#102

Post by icegreentea2 »

testing22321 wrote: post #67
gerikson wrote: post #5

Argh the liberal admixture of different units (mpg, kg, L, hr) in the first table really brings home that this is a UK piece.

Also the mpg figures are almost certainly “metric gallons”, 4.5l. US gallons are 3.8l

UK uses "imperial gallons", which are no more metric than US customary gallons. Expanded to 3 decimals, a UK/imperial gallon is 4.546L, and a US customary gallon is 3.786, and a US gallon is close to 3.8L, than a imperial gallon is to 4.5L.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#103

Post by aziaziazi »

GeertB wrote: post #68

The article makes it sound like the Tesla Semi is physically infeasible. Yet, it is in active use on a sufficient number of long-haul routes that ignoring this proof of existence undercuts some of the central points the post tries to make. 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…

Is regenerative breaking signifiant on long routes? I barely brake on long distance but the gas pedal is used almost uninterrupted. My naïve guess is truckers optimize even more their acceleration/beaking.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#104

Post by wjnc »

tobinfricke wrote: post #86
JoachimS wrote: post #66

Earlier quoted context omitted.

Or just take the foot of the pedal for a while.

Seems like a game-theoretic problem Taking their foot off the gas for a second only hurts them

Nope, it cascades back to all those in the same lane who’ve not yet decided on overtaking. It’s multi player game theory. Easiest way out I can think of is punishing both those too slow and too fast to create equilibrium. Haven’t thought about what this would do to other traffic going from the left lane to the outbound right via a mass of trucks in exactly the same speed.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#106

Post by nielsole »

mikeayles wrote: post #24
NomadicDaggy wrote: post #11

> This isn’t advisory. It’s a physical limiter in the engine’s ECU. The truck cannot go faster. 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?…

Probably the first thing to consider is the trucks have their speed calibrated periodically to ensure the accuracy of their tachographs (in the UK at least) so a truck doing 90kmph may show as 100kmph+ in a passenger car, I know my Volvo is 7% out, and my Seat is closer to 10% out. 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 g…

Also I heard there's tricks like going to the calibration with underinflated tires to eek out marginal speed gains.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#107

Post by morsch »

jjk166 wrote: post #58
secult wrote: post #28

For people that want to make the calculation: A truck does not need a 15 ton battery. In Europe, we have mandatory breaks for truck drivers. So you need a battery pack for max 400km of range, let's say 500km. When you have a break, you charge. For this, you need like 1500kWh battery pack, which weigths like ... wait, 15 tons. But this is not entirely correct, the real values reported are between 120-150Kwh/100km, tha…

Those mandatory breaks are 45 minutes long. You're not charging 750 kWh in 45 minutes. With a fast charger 750 kWh is 2 to 7 hours. At the far more common level 2 chargers it's 18 hours. Either mandatory breaks need to be substantially longer, you need a substantially larger battery than just that required to go between breaks, or you need some sort of specialized technology for dramatically speeding up charging rate…

Charge full overnight, top up at 300-350 KW once a day for 45 minutes. 600 kWh lfp battery weighing 4.5t. This seemed to work out fine for a guy on YouTube documenting his experiences. SoC wasn't a big deal in itself, flexibility in (overnight) stops more so, but still less than I expected.

https://www.youtube.com/@elektrotrucker

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#108

Post by izacus »

mschuster91 wrote: post #74
izacus wrote: post #44

Earlier quoted context omitted.

Tachographs are mandatory and monitored across the EU so I very much doubt that's really happening.

Just because something is mandatory, doesn't mean it's enforced. You got 6 million trucks registered in the EU alone [1], plus fleets of trucks registered in adjacent states such as Turkey or Serbia, or old trucks out of the new Eastern European states that predate their EU membership and, with it, mandatory governors. And loggers can be manipulated as well, if you do it right there is no chance of finding that out w…

The enforcement and verification of tachographs grew significantly in last 20 years across whole EU, even in our eastern european countries.

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.

Re: The Physics and Economics of Moving 44 Tonnes at 56mph

#110

Post by cucumber3732842 »

noah_buddy wrote: post #100
RobotToaster wrote: post #23

Earlier quoted context omitted.

From a commercial perspective, you would think the fuel savings from slipstreaming would more than make up for those five minutes.

At proper breaking distance, it’s probably negligible.

It probably still does fleet wide. Remember, the other driver isn't gonna brake hard without reason because he has an electronic narc in the cab that will tell his boss every time he does. The flipside of this is that the driver in the back isn't gonna imperil their "stats" by tailgating to save fuel because their own electronic narc will report that to their boss.

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.

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