What Happened To Sweden’s Slot Car EV Road?

A grey car sits in the background out of focus, its front facing the camera. It sits over an asphalt roadway with a metal rail extending from the foreground to behind the car in the distance. The rail has a two parallel slots and screws surrounding the slots running down the rail.

Many EVs can charge 80% of their battery in a matter of minutes, but for some applications range anxiety and charge time are still a concern. One possible solution is an embedded electrical rail in the road like the [eRoadArlanda] that Sweden unveiled in 2016.

Overhead electrical wires like those used in trolleys have been around since the 1800s, and there have been some tests with inductive coils in the roadway, but the 2 km [eRoadArlanda] takes the concept of the slot car to the next level. The top of the rail is grounded while the live conductor is kept well underground beneath the two parallel slots. Power is only delivered when a vehicle passes over the rail with a retractable contactor, reducing danger for pedestrians, animals, and other vehicles.

One of the big advantages of this technology being in the road bed is that both passenger and commercial vehicles could use it unlike an overhead wire system that would require some seriously tall pantographs for your family car. Testing over several Swedish winters shows that the system can shed snow and ice as well as rain and other road debris.

Unfortunately, the project’s website has gone dark, and the project manager didn’t respond when we reached out for comment. If there are any readers in Sweden with an update, let us know in the comments!

We’ve covered both overhead wire and embedded inductive coil power systems here before if you’re interested in EV driving with (virtually) unlimited range.

[via New Atlas]

60 thoughts on “What Happened To Sweden’s Slot Car EV Road?

      1. Potholes aren’t common in Sweden. Outside of dirt roads I’ve yet to see one. They don’t salt roads and repairs are done quick. As well they replace the roads regularly (which drives me crazy because the rerouting is horrible here.

    1. Tell me you didn’t read the summary without telling me you didn’t read the summary:

      “Testing over several Swedish winters shows that the system can shed snow and ice as well as rain and other road debris.”

      Admittedly it doesn’t say how, but the issue is certainly addressed.

      1. It probably can, but not well enough. Eventually it’s going to get clogged up with simple dust and mud.

        And then there’s the melt season every spring. It does little good if the slot is simply flooded with water.

          1. Road dust is highly abrasive, so the pickups would wear out extremely quickly, and having a live wire flooded with water is obviously not going to work.

            Sweden has this thing called winter, where the roads ice over for months and they have to use ash and grit – or salt – to clear it. When the melt comes, if the slot is entirely packed with grit, it’s not going anywhere.

      2. Sounds like they didnt test it in regions where they sand the roads. Having driven in northern sweden one marvels at the sparse lightning of the roads there, would be a major undertaking to electrify that roadnet

  1. Yeah I’ll give you good odds that it just didn’t end up being robust enough to last seven years. They saw it didn’t hold up nearly as well as you’d like to describe it and shut it down. Remember solar freakin’ roadways? Yeah roads weather very hard, you can’t easily cram extra infrastructure into them.

    1. This. Solar freaking roadways had a reported solar panel efficiency degradation in the order of a frigging 70% Per Year, a French firm who did the same and managed to have Pete Butiegeg do a promotional video standing right next to all of the three square meters of solar panels that were installed *in the bicycle lane* (not the car lane) experienced a similar loss of around 50% p.a., which made them abandon the entire venture.

      1. I’ve always thought we should be covering the roads with awnings and putting solar panels on them. Panel efficiency is finally reaching a point where it’s a viable option.

        Freeways for example. If you figure a minimum right of way of 25 feet from the center of the road the average four lane freeway has a corridor of at least 180 to 200 feet depending on terrain. Assuming you could cover the entire right of way with an awning equipped solar panel array that would give you nearly 22 acres of solar panels per mile. They wouldn’t have to be that tall either, a bit higher than overpass height would be sufficient.

        Granted this would be a massive project costing hundreds of millions with a long term return on investment. It would have the advantages of economy of scale, standardized parts, linear infrastructure, and serve as a backbone for all kinds of other services. Cameras, sensors, communications hardware, and all kinds of other stuff could be hung from the underside of the awnings. Might save on road wear and tear when it comes to ice and snow too.

        1. No, no, no. First, by the time you install all that infrastructure, technology wii have advanced to the point it is no longer needed. Secondly, when I’m out on the road, I enjoy looking at the beautiful skies and would not appreciate looking at a bunch of awnings, cables, birds nest, etc. third, I doubt we could employee enough maintenance people to keep any reasonable length of the solar powered awnings functioning. Forth, how do you transmit that much collected power for use/storage?

          1. a) People enjoyed good horse ride before, we denied them this pleasure with our damn cars. Get over it.
            b) Population is rising and demand defines offer, so if there will be demand, enough workforce will be eventually provided
            c) Storage and transmission should be done on the local level. I don’t know about US ot Australia,
            but in Europe we have plenty of towns, villages and industrial objects along autobahns. You won’t need to go far away, electricity will be gladly consumed right there, in quite close vicinity.

            Other than that, awnings protects road and cars from elements. You can even use PVT panels in the vicinity of residential blocks to provide them with heating and cool pannels down. But that surely adds to complexity.
            And why are we so fixed on highways and autobahns? Surely, there are plenty of places in towns, where nice solar awning would be welcomed to provide shade and electricity.

          2. If you really love the open sky that much use the back roads…

            That said I don’t think you can really turn the major routes into solar power tunnels – its going to be dark underneath them which leads to a whole bunch safety issues with folks merging or leaving the road being effectively blinded by changing light levels at a really bad moment. Putting them down the centre divide and perhaps the side of the road with the odd overpass to join the whole system together is probably plausible on a safety front. It certainly makes sense from the point of view of getting power without having to take the bulldozer to nature a heap, and works well from the point of view of being able to get access for what little maintenance a solar panel can require (basically clean it every now and then should be enough most of the time)

          3. The potential for damaging debris comes into play here. If you want to put the awnings along the roadway, fine. But over? You do know how gravity works, right? And a few impacts would cause damage that would bring an entire roadway to a stop. No thanks.

            Now force awnings over new warehouse construction, along roadways…then you have something. Many roadways in the US have industrial areas adjacent to them.

  2. That video has written “scam”, “delusion” and “propaganda” written all over it. Instead of showing us some details we only get to see happy people having a good time, with a steadily moving cameras and big font slogans covering what could have been a glimpse of some technical detail.

    That said, we do get a few split seconds of the rail, and it looks incredibly flimsy (as does the photo above). Has anyone considered the forces in play should a car (or a frigging van) veer to one side or the other? That may very readily lead to Totally Unscheduled Rapid Disassembly of the collector, or parts of the car body.

    And yet again, we have a technology that was tried and true but just *had* to be thrown by the wayside at some point in the past, because now we have CARS. Underground conduits were a thing e.g. in London where they had doubledecker streetcars with underground conduits in the central and overhead catenaries in the outer parts of London. Everything ripped out and thrown onto the trash heap. But now of course we can do better, and we need no pesky rails, even though those pesky rails (combined with the moderate speeds of an inner urban transport service) were all the reason underground circuits were viable in the first place.

        1. The second segment sounds nice with the wireless charging (without getting into if it actually works, etc) but showing that bus tail-gating the he-double-hockey-sticks out of that car was really bad.

      1. Unfortunately thunderfoot has gone well off the deep end, making trivially disprovable claims in order to ‘debunk’ fully functioning systems (e.g. how Falcon 9’s powered landing is supposedly impossible).

    1. Yep, they actually have a test site for it on a public road here in Lund where I live. It is a few hundred meters or so. If I understand correctly, it builds on a safe handshaking procedure to output power only to a small part of the strip right under the vehicle.

    1. Currently the “80% in minutes” club is pretty small and it depends heavily on what the vehicle and charging station are capable of, but some of the more recent (i.e. last couple years) EVs that support level 3 fast charging can do it in low double digit minutes. If you can find a sufficiently powerful charging station the Hyundai Ioniq 5 can go from 10 to 80% in <20 minutes.

      1. Rapid charging is very hard on batteries and can only be done a limited amount of times.
        Also, it is not possible when the battery temperature is below 0°C because it causes lithium plating and destruction of the cells.

        1. FUD!

          No, there is no “limited amount of times” you can do it.

          EV batteries are actively cooled/heated. The EV vehicle always determines how fast the battery will be charged, so if it is fast charging, it has already determined it is OK to do so.
          When using the in-car routeplanner with charging stops, the EV actually prepares the battery to be ready (right temperature) for fast charging when arriving at the charging station.

          Yes, there is a slight increased degradation in battery capacity between exclusively fast and slow charging, which is ~4% in 50.000 miles / 80.000 km.
          This is less difference than the effect of different driving styles on the battery.

          1. I bet Musk told you that, from the same company who destroyed flash RAM by writing to it a million times (or trying to at least).
            The same guy who also a million times overstated projections and capabilities of all stuff he is involved with.
            So excuse me if I’m not convinved so easily.

        2. I just read a paper on asymmetric charging, with the battery charging at 60 degrees Celsius. They got impressive cycle life at 6C charge rates. Quickly getting the batteries to 60 degrees could probably be done by simply putting a heating wire in the core, but actually keeping it steady there at 6C charging would be a bit of a challenge.

          1. I just looked it up, and it’s certainly a neat trick. I doubt you would actually struggle to keep the battery’s temperature elevated once pumping 6C in continuously, since they’ll self-heat from their own internal resistance anyway. The practical problem seems to be that the cells quickly suffer from materials degradation at 60C, and so must be rapidly cooled afterward so their temperature is elevated only for the 10 minutes of active charging. That’s relatively easy in a lab when you’re experimenting with just one cell, but is incredibly gnarly when you have an 800KG battery pack. I work on high flight volume UAVs with battery packs that gradually heat up over the course of a mission, and it takes considerable active cooling just to get them cool enough for another flight cycle faster than it otherwise takes just to charge them again.

            A more practical technique that’s been in use for years is pulse charging. It gives a moderate gain in charge rate without impacting degradation, allowing you to i.e. achieve the equivalent of 1.2C for the same degradation as 1C. All it requires is brief periodic rest periods, such as 9 seconds on at 1.3C and 1 second off. I’ve implemented it myself for an EV project that used CHAdeMO chargers.

    2. Tesla’s site claims you add 200 miles of range in 15 minutes. That isn’t necessarily 80%, but it gives a pretty good idea that these things can charge fast. I was on a trip and went in for a bathroom break and snacks at a store. I didn’t time it but it finished charging before I came back. These charging rates also aren’t the fastest, with some cars having 800V systems that can be faster.

  3. So, I originally composed a snarky comment about how this idea was lame and probably only existed to unlock some sweet, sweet, research grant, just like hydrogen or the stupid solar road. I deleted it because I thought it was too harsh. Live and learn I guess.

  4. Trucks on trunk routes often dont/wont. And with all this technology the raod train could be built up with that in mind.
    Overhead lines make sense for bus and truck. For many UK ciities we had trolley buses as they were called until we ripped them out for the car to replace. But it’s a logical system for buses. Even if the bus has batteries then you dont need as many wires. Putting a massive amount of batteries into a bus is illogical. Espeically when you also need to consider HVAC and in sumer tons of heat to get rid of. overhead wires would help a lot.

  5. This is a junk technology that has little basis in practical reality. There is no AGW. Even NASA has posted satellite maps of some parts of the world greening thanks to human intervention. The energy inputs to build and maintain far exceed any alleged environmental benefits.

  6. I understand that no one’s mind will be changed on this issue, but someone still needs to state the counterpoints:
    * The article makes no claims about climate change. Even if you don’t believe oil causes climate change, surely you understand that it is a finite resource so mankind must have alternatives?
    * “parts of the world greening” doesn’t disprove climate change at all.
    * Anthropogenic global warming is accepted by an overwhelming majority of scientists. You can disagree with the consensus but you must acknowledge that people who do that are usually wrong.
    * If NASA is your standard, they are pretty clear on the issue: https://climate.nasa.gov/scientific-consensus/

    1. NASA has to toe a line to who is currently in office for funding. So I expect (and do) see more ‘environmental’ talk and initiatives there to keep the dough rolling in…. If you having been following the ‘content’ on their website over the last few years it has changed ‘radically’.

      1. While I actually agree with you, it is good to remember that the current fossil fuel system has an efficiency in the range of 10%-20%. It used to be half that (2x worse) . The world got along just fine. So an option that is somewhat less efficient but otherwise economic and convenient, is still quite feasible. And by the same token, something efficient, but prohibitively inconvenient does not get used.

  7. While everyone debate how great this technology is, it main point of the article is that the project has gone dark. That is not a sign that things went very well.

  8. The rail was removed and the road repaired in the summer of 2022. I bicycle on that road often in the summer and am selfishly glad as it’s not so nice to have any rails parallel to the direction of travel when riding on narrow bicycle tires.

  9. My guess: civilization continues to decay until it collapses onto itself. People live simple lives in scattered communities, spending their days farming and tending to their animals, but benefitting from the simple pleasure of viewing memories of a bygone era on the pile of smart phones and tablets that still barely work. In time, Kevin Costner’s descendants start delivering mail via horseback. A new federation of communities form and organize enough to fight off the cannibals for good. We go back to internal combustion engines.

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