Truckers measure their 0-60 times in minutes as opposed to seconds. To prevent slow trucks from holding up traffic (and getting rear ended by faster cars), many highways include climbing lanes. But things are changing. New electric trucks can offer far quicker acceleration. Tesla claims their Semi can get from 0-60 with a full 80,000 pound load in just 20 seconds. Surely this will mean better traffic flow in a lot of places?
Does accelerating that quickly drain the battery more?
That's really not fast, says the owner of a 128hp automobile.
Considering there's not going to be a majority switchover from ICE to electric trucks for at least 15-20 years, there's not much reason to change things to accommodate a few faster trucks.
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
If that's the case, then I imagine a lot of companies would instruct their drivers to not put the pedal to the metal.
Quote from: kphoger on October 28, 2022, 05:04:17 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
If that's the case, then I imagine a lot of companies would instruct their drivers to not put the pedal to the metal.
Or they'll be speed-limited as well as acceleration-limited.
Since when has 0-60 in twenty second been considered fast? That would have been horrifically slow even the Malaise Era.
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Quote from: Max Rockatansky on October 28, 2022, 05:21:09 PM
Since when has 0-60 in twenty second been considered fast? That would have been horrifically slow even the Malaise Era.
It's probably fast enough to not warrant separate truck climbing lanes.
Part of me feels like this could potentially affect how fast certain roads wear (maybe on-ramps will have to be repaved a little more often?), but honestly I don't think that it would affect it much.
Speed governors are going to become mandatory in more and more heavy vehicles (including EV cars). Too many idiots to handle going 0-60 in that short of a span with that kind of weight behind it. I foresee our rate of deaths per miles driven skyrocketing even more than it already is.
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Not all of it, unless you've invented perpetual motion.
Quote from: kernals12 on October 28, 2022, 05:43:55 PM
Quote from: Max Rockatansky on October 28, 2022, 05:21:09 PM
Since when has 0-60 in twenty second been considered fast? That would have been horrifically slow even the Malaise Era.
It's probably fast enough to not warrant separate truck climbing lanes.
Truck climbing lanes have nothing to do with acceleration...they exist because a truck's top speed is slower up a hill, not because trucks take longer to get to that top speed. Both are dependent on engine power, though, regardless of how that power is generated. So trucks might get to their (still slow) top speed on hills more quickly with an electric engine - doesn't mean they won't still be going slowly and be a danger to other traffic. Keep the truck lanes.
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
That doesn't affect whether it's more efficient to accelerate slowly or to have maximum acceleration. The energy recaptured with regenerative braking is the same regardless of whether the driver had the petal to the metal when accelerating earlier.
I'm curious how truckers will adapt to the additional acceleration. One of the safety impacts is that the potential need for panic braking during a full acceleration application causes a not insignificant increase in braking distance as the maximum acceleration rate increases, particularly downhill. Locomotive engineers need to be keenly aware of this when hauling "light freight", but I'm not sure how most truckers will adapt. In my world, we highly encourage (and sometimes require) that the electric traction control systems provide a [safe means] of limiting the acceleration when rate the motors and controllers are designed to be capable or more than required for [normal use].
Actual question, how are these E-trucks going to get down steep grades without the assist of a Jake Brake and traditional gear shifting?
Quote from: Max Rockatansky on October 29, 2022, 03:02:35 PM
Actual question, how are these E-trucks going to get down steep grades without the assist of a Jake Brake and traditional gear shifting?
Regenerative braking.
Electric motors apply torque instantaneously, so it's not surprising that a fully-loaded truck with an electric motor could get off to a (relatively) jackrabbit start. But on most congested highways, it's the governored trucks going 65 mph or less that are the problem.
Quote from: GaryV on October 28, 2022, 09:21:39 PM
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Not all of it, unless you've invented perpetual motion.
It's like Snowpiercer, but a truck...
Quote from: SectorZ on October 30, 2022, 08:17:21 AM
Quote from: GaryV on October 28, 2022, 09:21:39 PM
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Not all of it, unless you've invented perpetual motion.
It's like Snowpiercer, but a truck...
Even Snowpiercer started breaking down as the years wore on. That's why Winford (in the movie) kept harvesting kids from the caboose, some Engine Eternal.
Quote from: Road Hog on October 30, 2022, 02:04:36 AM
Electric motors apply torque instantaneously, so it's not surprising that a fully-loaded truck with an electric motor could get off to a (relatively) jackrabbit start.
This wasn't true until the suppliers of traction motor controllers switched over to variable frequency inverters in the late 1990s. Before then, the best controllers utilized diode choppers to modulate the voltage and allow tighter control of acceleration, jerk and snatch.
Quote from: Max Rockatansky on October 29, 2022, 03:02:35 PM
Actual question, how are these E-trucks going to get down steep grades without the assist of a Jake Brake and traditional gear shifting?
Quote from: kernals12 on October 29, 2022, 05:49:08 PM
Regenerative braking.
Regenerative braking is also useful in preserving the life of friction braking elements such as brake shoes, discs and drums. I still don't understand why diesel electric hybrid technology hasn't taken hold in the panel truck and service truck industry, because of the inherent cost savings related to the brake system. This cost savings won't apply to tractor-trailers, as the trailer still needs its friction brake applications coordinated with the big rig's brakes on the cab unit. But regenerative braking will still work quite well on big rig's, just like on railroad locomotives.
Quote from: Max Rockatansky on October 30, 2022, 10:25:55 AM
Quote from: SectorZ on October 30, 2022, 08:17:21 AM
Quote from: GaryV on October 28, 2022, 09:21:39 PM
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Not all of it, unless you've invented perpetual motion.
It's like Snowpiercer, but a truck...
Even Snowpiercer started breaking down as the years wore on. That's why Winford (in the movie) kept harvesting kids from the caboose, some Engine Eternal.
Ha ha I've never seen the movie. The show, now four seasons in, has gotten pretty ridiculous with the inconsistencies of how it operates (and that there was a main train and a second train). They pulled a "don't dwell too much on the science" routine with it.
Quote from: SectorZ on October 30, 2022, 05:58:21 PM
Quote from: Max Rockatansky on October 30, 2022, 10:25:55 AM
Quote from: SectorZ on October 30, 2022, 08:17:21 AM
Quote from: GaryV on October 28, 2022, 09:21:39 PM
Quote from: kernals12 on October 28, 2022, 05:43:19 PM
Quote from: JoePCool14 on October 28, 2022, 04:58:39 PM
Quote from: kphoger on October 28, 2022, 04:55:56 PM
Does accelerating that quickly drain the battery more?
I would assume it does. Just like accelerating faster in a car with an ICE uses more gas.
Unlike ICE cars, electric cars can then recapture the energy used during acceleration during braking.
Not all of it, unless you've invented perpetual motion.
It's like Snowpiercer, but a truck...
Even Snowpiercer started breaking down as the years wore on. That's why Winford (in the movie) kept harvesting kids from the caboose, some Engine Eternal.
Ha ha I've never seen the movie. The show, now four seasons in, has gotten pretty ridiculous with the inconsistencies of how it operates (and that there was a main train and a second train). They pulled a "don't dwell too much on the science" routine with it.
Conversely I've never seen the show. In the movie there was only one train and it crashes at the end. Presumably everyone dies even though there is indications the Earth is warming back up. The movie variant of Snowpiercer is over the top and reminds me of an 80s Robocop-style movie in the best way possible. It's definitely something I would recommend giving a watch.
Most current medium to heavy-duty truck EV applications employ governors to roughly mimic current diesel truck performance. It's generally a bad idea to have things like school buses and box trucks laying rubber from stoplights or power-on drifting around corners.
The last thing truck manufacturers want to see is their expensive new products suffering breakdowns and becoming roadway menaces at the hands of maniac drivers. They also have to keep the battery packs alive for at least 250,000+ miles.
While hooning Tesla semi trucks makes for great video, you'll never see that on a public roadway.
Quote from: Dirt Roads on October 30, 2022, 03:57:25 PM
Quote from: Road Hog on October 30, 2022, 02:04:36 AM
Electric motors apply torque instantaneously, so it's not surprising that a fully-loaded truck with an electric motor could get off to a (relatively) jackrabbit start.
This wasn't true until the suppliers of traction motor controllers switched over to variable frequency inverters in the late 1990s. Before then, the best controllers utilized diode choppers to modulate the voltage and allow tighter control of acceleration, jerk and snatch.
Quote from: Max Rockatansky on October 29, 2022, 03:02:35 PM
Actual question, how are these E-trucks going to get down steep grades without the assist of a Jake Brake and traditional gear shifting?
Quote from: kernals12 on October 29, 2022, 05:49:08 PM
Regenerative braking.
Regenerative braking is also useful in preserving the life of friction braking elements such as brake shoes, discs and drums. I still don't understand why diesel electric hybrid technology hasn't taken hold in the panel truck and service truck industry, because of the inherent cost savings related to the brake system. This cost savings won't apply to tractor-trailers, as the trailer still needs its friction brake applications coordinated with the big rig's brakes on the cab unit. But regenerative braking will still work quite well on big rig's, just like on railroad locomotives.
That's another thing: regenerative braking could eliminate the need for runaway truck lanes... and prevent a great number of gruesome accidents.
Quote from: Dirt Roads on October 30, 2022, 03:57:25 PM
Regenerative braking is also useful in preserving the life of friction braking elements such as brake shoes, discs and drums. I still don't understand why diesel electric hybrid technology hasn't taken hold in the panel truck and service truck industry, because of the inherent cost savings related to the brake system. This cost savings won't apply to tractor-trailers, as the trailer still needs its friction brake applications coordinated with the big rig's brakes on the cab unit. But regenerative braking will still work quite well on big rig's, just like on railroad locomotives.
Quote from: kernals12 on October 31, 2022, 01:24:07 PM
That's another thing: regenerative braking could eliminate the need for runaway truck lanes... and prevent a great number of gruesome accidents.
That's only correct for large trucks that are not pulling trailers. The big rigs still have a huge payload in the trailer that must be controlled with pneumatic-controlled friction brakes. Just like locomotives, regenerative braking in the cab can create a strong counterforce against downhill gravity, but this only interacts with the trailer as much as the [hitch] can distribute the force. On AAR-standard freight trains, that is a function of the drawbar strength of the couplers. Fifth-wheel hitches transfers this braking force through a vertical king pin, and I'm not so familiar how these regenerative braking forces interact with the trailer.
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen. I believe there are a few other circumstances where it can be disabled as well.
https://insideevs.com/news/619269/tesla-semi-effortless-acceleration/
Here's the Tesla semi in action and it looks pretty quick. Also, Tesla says that the truck can go at highway speed limits even at a 5% grade.
Where's that Cybertruck I've been hearing so much about? The fact that Tesla says this and not a more substantial automaker makes me doubt the technology is really that far along.
Over/under on deliveries actually taking place in December anyone?
Quote from: vdeane on November 01, 2022, 08:44:30 PM
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen.
Maybe they can mine Bitcoin with it. :-D
Quote from: Max Rockatansky on November 01, 2022, 09:43:17 PM
Where's that Cybertruck I've been hearing so much about? The fact that Tesla says this and not a more substantial automaker makes me doubt the technology is really that far along.
Over/under on deliveries actually taking place in December anyone?
I hope you didn't actually bet any money on that
https://www.axios.com/2022/12/02/tesla-semi-trucks
This great news for Connecticut's decades old plans to widen I-84 from Waterbury to the New York State line. Large portions of it already have an extra truck climbing lane going in one direction, so all they need to do is classify them as regular travel lanes and then add a lane in the other direction.
I was too busy wishing for global warming and tripping over sidewalks to make it to my bookie.
I'm glad you're here though, seems you have another junior futurist peer who is presently working on grapple hook technology:
https://www.aaroads.com/forum/index.php?topic=32429.msg2793478#new
They will have to take better care with wrapping pallets and loading the trailer, else load shifting will increase with additional acceleration. Trailer door latches better be verified to not be sketchy either. I can envision loads dumping out the back of older trailers otherwise.
Tesla has now officially delivered its first Tesla Semi Electric cab to Pepsico. The headline on one of last night's articles indicated that it was "3 years late", but I do not know whether that is a referring to a production delay or the actual delay from this procurement. I'm curious as to whether the lifecycle costs are really going to be achieved (they certainly will achieve them if truckers can get regular access to any free charging stations). But this will be our first look at "what happens when get fast" (ergo, accelerates rapidly when unloaded). Who knows, maybe NASCAR can start a new series of race truck.
https://www.msn.com/en-us/autos/news/tesla-delivers-first-semi-electric-truck-to-pepsi/ar-AA14OTpM
Quote from: kernals12 on December 01, 2022, 11:58:55 PM
Quote from: Max Rockatansky on November 01, 2022, 09:43:17 PM
Where's that Cybertruck I've been hearing so much about? The fact that Tesla says this and not a more substantial automaker makes me doubt the technology is really that far along.
Over/under on deliveries actually taking place in December anyone?
I hope you didn't actually bet any money on that
https://www.axios.com/2022/12/02/tesla-semi-trucks
This great news for Connecticut's decades old plans to widen I-84 from Waterbury to the New York State line. Large portions of it already have an extra truck climbing lane going in one direction, so all they need to do is classify them as regular travel lanes and then add a lane in the other direction.
Yes. Just "reclassify" climbing lanes.
*eyeroll*
Well MMM seems to want to develop electromagnets on helicopters and to implement graphing hooks to slow truck travel down.
No, roadman65, you're the only one who wants to implement graphing hooks. Four times now.
I really liked the game Bionic Commando.
Quote from: 1 on December 02, 2022, 01:50:20 PM
No, roadman65, you're the only one who wants to implement graphing hooks. Four times now.
What?
Quote from: roadman65 on December 02, 2022, 02:20:50 PM
Quote from: 1 on December 02, 2022, 01:50:20 PM
No, roadman65, you're the only one who wants to implement graphing hooks. Four times now.
What?
I'm not sure about the "four times" part, but you're the only one who has suggested graphing hooks. See my previous post.
I never suggested a crazy idea like that. I was maybe friendly sarcastic, but someone else has been coming up with ideas that are far out including a way to China through the center of the Earth and other stuff.
Just like someone else responding to a roller coaster thread claiming the PA Turnpike is a rollercoaster. According to you, he would be serious about that when in fact he was poking fun at the individual who created a thread that the PA Turnpike is unworthy of being a toll road because it's too winding.
Obviously you've been away from the forum a while, but we have a user who makes Fritz Owls ideas look good, as he's been posting several times a day crazy ideas from electromagnets to having I-80 go to Providence and just recently posted other crazy ideas yesterday in one thread.
Read MultiMillionMiler in One Thread and many other threads that have been locked lately.
Quote from: Rothman on December 02, 2022, 01:52:50 PM
I really liked the game Bionic Commando.
That game is the shit, one of my favorites since I was a kid. Lobbing a rocket into "not-Hitler's" face at the end is always incredibly satisfying.
Kpoger show me the post I came up with the so called idea to use graphing hooks to stop a runaway rig on I-70 or any idea so ridiculous. If you believe that I think a graphing hook could solve a runaway truck problem, then I got oceanfront property in Great Bend, KS to sell you.
Quote from: roadman65 on December 02, 2022, 02:36:58 PM
Kpoger show me the post I came up with the so called idea to use graphing hooks to stop a runaway rig on I-70 or any idea so ridiculous. If you believe that I think a graphing hook could solve a runaway truck problem, then I got oceanfront property in Great Bend, KS to sell you.
If you search this forum for the phrase "graphing hooks", the only posts that come up are from you or people responding to you.
Quote from: kphoger on December 02, 2022, 03:41:46 PM
Quote from: roadman65 on December 02, 2022, 02:36:58 PM
Kpoger show me the post I came up with the so called idea to use graphing hooks to stop a runaway rig on I-70 or any idea so ridiculous. If you believe that I think a graphing hook could solve a runaway truck problem, then I got oceanfront property in Great Bend, KS to sell you.
If you search this forum for the phrase "graphing hooks", the only posts that come up are from you or people responding to you.
I for one want to see Kernals vs MMM. I'll promote any fictional grapple hook technology no how absurd to make this happen.
WTF is a "graphing hook"? Isn't the device called a "grappling hook"?
We have a metric ton of nerds mathematicians here. Someone please show me an example of a graphing hook on a Cartesian plane.
Quote from: Road Hog on December 02, 2022, 08:52:22 PM
We have a metric ton of nerds mathematicians here.
When highway plans were metric in the late 1990s, that was referred to as a megagram.
Quote from: bulldog1979 on December 02, 2022, 08:47:27 PM
WTF is a "graphing hook"?
I have no idea what it is. I was just agreeing that |roadman65| is the one who brought them up.
This is one possible result of graphing HOOK:
(https://i.imgur.com/BaHejXq.png)
Quote from: Road Hog on December 02, 2022, 08:52:22 PM
We have a metric ton of nerds mathematicians here. Someone please show me an example of a graphing hook on a Cartesian plane.
I think you need non-Euclidian geometry to use a graphing hook.
Quote from: vdeane on November 01, 2022, 08:44:30 PM
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen. I believe there are a few other circumstances where it can be disabled as well.
Perhaps the current could be run through an electric heater. Build it like a radiator, with heating elements attached to cooling fins to dissipate the heat. Include a fan to increase cooling and burn more energy. On a big truck, this wouldn't replace the friction brakes, but it would reduce the need for them like the engine brake does.
Quote from: Road Hog on December 02, 2022, 08:52:22 PM
We have a metric ton of nerds mathematicians here. Someone please show me an example of a graphing hook on a Cartesian plane.
y = x
1/2 looks close, I would think. You reach in and snag the origin with it.
Quote from: wxfree on December 04, 2022, 01:23:36 AM
Quote from: vdeane on November 01, 2022, 08:44:30 PM
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen. I believe there are a few other circumstances where it can be disabled as well.
Perhaps the current could be run through an electric heater. Build it like a radiator, with heating elements attached to cooling fins to dissipate the heat. Include a fan to increase cooling and burn more energy. On a big truck, this wouldn't replace the friction brakes, but it would reduce the need for them like the engine brake does.
That's how diesel/electric locomotives brake on long descents. They use a resistive heating grid to provide a large load on the electric trucks running as generators on downhills. Semi's might consider something like this on a smaller scale for the edge cases where they start off full and then need to go downhill right off the bat, leaving not much battery capacity to provide the load to slow the vehicle with regen.
Quote from: Dirt Roads on December 02, 2022, 11:10:22 AM
Tesla has now officially delivered its first Tesla Semi Electric cab to Pepsico. The headline on one of last night's articles indicated that it was "3 years late", but I do not know whether that is a referring to a production delay or the actual delay from this procurement. I'm curious as to whether the lifecycle costs are really going to be achieved (they certainly will achieve them if truckers can get regular access to any free charging stations). But this will be our first look at "what happens when get fast" (ergo, accelerates rapidly when unloaded). Who knows, maybe NASCAR can start a new series of race truck.
https://www.msn.com/en-us/autos/news/tesla-delivers-first-semi-electric-truck-to-pepsi/ar-AA14OTpM
It would take quite a bit of subsidy for anyone to provide free charging using megawatt level chargers. I don't see that happening with current electrical prices as well as the amount of infrastructural changes required to get them setup in the first place. To have more than a handful in any one spot pretty much requires an electrical substation setup just to handle it, unless you're doing acres of solar with Tesla Megapacks, which also won't come cheaply.
Quote from: vdeane on November 01, 2022, 08:44:30 PM
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen. I believe there are a few other circumstances where it can be disabled as well.
Quote from: wxfree on December 04, 2022, 01:23:36 AM
Perhaps the current could be run through an electric heater. Build it like a radiator, with heating elements attached to cooling fins to dissipate the heat. Include a fan to increase cooling and burn more energy. On a big truck, this wouldn't replace the friction brakes, but it would reduce the need for them like the engine brake does.
Quote from: MikieTimT on December 05, 2022, 10:24:39 AM
That's how diesel/electric locomotives brake on long descents. They use a resistive heating grid to provide a large load on the electric trucks running as generators on downhills.
Regenerative braking often requires a large series of fans to dissipate the heat. One of the [many] reasons that locomotives turn off the regenerative braking below a certain speed is that they would need higher speed fans when the train speed (ergo, frontal wind speed) gets below a certain ability to move the necessary volume of air (in addition to the fans). Presumably, the same would be necessary for trucks with regenerative braking. It is interesting that many hybrid cars already employ regenerative braking, but those tend to be the ones with "mild hybrid" technology whereby the electric motor assist is not capable of full deceleration downgrade (or full acceleration upgrade, for that matter).
Quote from: Dirt Roads on December 05, 2022, 12:51:53 PM
Quote from: vdeane on November 01, 2022, 08:44:30 PM
Also: regenerative braking requires that there be somewhere for that energy to go. If the battery is full at a given moment, there isn't, so no regen. I believe there are a few other circumstances where it can be disabled as well.
Quote from: wxfree on December 04, 2022, 01:23:36 AM
Perhaps the current could be run through an electric heater. Build it like a radiator, with heating elements attached to cooling fins to dissipate the heat. Include a fan to increase cooling and burn more energy. On a big truck, this wouldn't replace the friction brakes, but it would reduce the need for them like the engine brake does.
Quote from: MikieTimT on December 05, 2022, 10:24:39 AM
That's how diesel/electric locomotives brake on long descents. They use a resistive heating grid to provide a large load on the electric trucks running as generators on downhills.
Regenerative braking often requires a large series of fans to dissipate the heat. One of the [many] reasons that locomotives turn off the regenerative braking below a certain speed is that they would need higher speed fans when the train speed (ergo, frontal wind speed) gets below a certain ability to move the necessary volume of air (in addition to the fans). Presumably, the same would be necessary for trucks with regenerative braking. It is interesting that many hybrid cars already employ regenerative braking, but those tend to be the ones with "mild hybrid" technology whereby the electric motor assist is not capable of full deceleration downgrade (or full acceleration upgrade, for that matter).
Actually, *all* hybrid cars have regenerative braking. Regenerative braking is an inherent feature of an electric motor; running it in reverse turns it into a generator.