Hacker News Reader

Comment by PLenz | Hacker News Reader

Trains are already crazy efficent both fuel and operational people wise - in fact this negates one of railroading great efficencies, slack (that 2 mile freight train already starts one car at a time). Also subtracting, cars are going to need to bunch up anyway at passing sidings to let cars go by opposite direction. Besides, the real cost is railroading is MOE and MOW (including land taxes here) and this solves neither of those issues. Could be interesting for locals and LCL traffic but those haven't been big parts of railroading in decades.

View on HN

Rail is insanely efficient over long distances but these seem to be optimized for shorter route with a 500 mile limit ignoring battery degradation. For rural lines that might see 10 trains a day increasing utilization via ultra short trains on local routes could be very profitable for a railroad as long is it doesn’t require people or interfere with existing traffic.

Basically if a tiny spur for loading and unloading doesn’t need to fit a full sized train they you can cheaply add a lot of stations.

I think the true value of this isn't replacing trains during the long haul portion, but rather the "last mile". The logistical infrastructure for getting freight from train depot to other depots is about as efficient as it can get BUT getting that freight to its final destination is still inefficient. A 2 mile long train needs to tediously be loaded onto trucks, which will all burn gasoline to get to where-ever they need to go.

In Switzerland a lot of factories and warehouses have train lines built into the infrastructure to try to solve this issue, but its not always feasible to a) build that infrastructure out, especially in the US, and b) use a train to transport a few containers to its destination.

If these electric train cars could be built to interface with normal train cars, they could still take advantage of the biggest efficiency of freight trains, while also helping solve the last mile problem by splitting off from the train to get closer to their final destination.

In large cities you could lay more tracks specifically for these cars to get closer to major industry areas. Land rights are an issue but you could lay track in roads. Chicago has some remnants of street running trains, but the biggest issue is a train that's ~200 yards long is a lot more disruptive to traffic than something that's the size of a semi truck.

That's what locals are, the last mile (or hundred mile) trains that get made up out of cars that have moved long distances already. Railroads hate thise trains. The money is in unit trains, all one commodity going from one place to one other place over a very long distance - the exact opposite profile of locals. Railroads started making this transition in the 60s and 70s as they shed branches and secondary mains and excellerated into the 80s and 90s by spining off shortlines that would focus on local traffic.

I can think of numerous political/social/business reasons for this to go wrong, but can't really think of any way in which this isn't more efficient than the status quo and so seems inevitable on some timescale.

Before, long train that has to move as one unit. After, long train that can optionally split and recombine at will with other long trains coming and going from different places.

You've essentially described the trucking industry, without the need to figure out linking or being limited to rail routes.

Without the train length, you lose the efficiency. The sum of added traction drivers and energy storage on each car exceeds any savings you might gain by autonomous operations or possibly getting rid of the traditional locomotives.

Convoy based self-driving tech on interstates is roughly mature enough as-is to operate as a drafting, self assembled train, if there was a desire/demand to implement it.

But that goes back to political/social/business reasons.

one of railroading great efficiencies, slack (that 2 mile freight train already starts one car at a time)

Is that right? Maybe before roller bearings, when overcoming starting friction was a huge problem.[1] But all US railroad cars in interchange have had roller bearings since about 1992.

Normal starting procedure is to move the engine very slowly until the end of train device reports motion, indicating all the slack has been taken out. Then apply power.

[1] https://www.youtube.com/watch?v=R-1EZ6K7bpQ

Exactly,slack is the space give to each car if the train to move before the next car has to. Starting cars rolling is the most energy expenssive thing the motive power has to do. So once you take the slack out on a single car it's pretty cheap to keep it rolling (Issac Newton to the rescue!) - then on to the next car. So a train starts rolling one car at a time as the slack gets taken out. Crazy efficent.

> Starting cars rolling is the most energy expenssive thing the motive power has to do.

Is it, really? It might require an not unconsiderable amount of force, but due to P = F x v, at low speeds even high forces don't require that much power. If anything, it's rather that you're friction-limited at that moment.

> Also subtracting, cars are going to need to bunch up anyway at passing sidings to let cars go by opposite direction.

Sounds like the cars are already “bunched up”:

> “We think our platoon sizes are ideally between ten and 50 cars,” Matt Soule, CEO of Parallel Systems, told Ars.

Edit: Also, you say:

> … [T]he real cost is railroading is MOE and MOW (including land taxes here) and this solves neither of those issues.

But the article mentions that the maximum utilization of a rail line is currently limited by how close trains can follow one another safely. If new technology can increase that limit, the capital costs of the rail line can be distributed across more units of freight.

But the article mentions that the maximum utilization of a rail line is currently limited by how close trains can follow one another safely.

Back in the 90's, Wisconsin Central was a major freight railroad in the midwest (I don't know if it still is), and was trying really hard to be allowed to automate most of its freight lines.

Part of the problem was that for legal reasons, it had to convince every little town along the way to buy into the idea of automated freight trains rolling through their towns. I went to a bunch of public hearings about it.

At the time, WC had already reduced its trains to one or two humans (I think just one), and it was really easy for local politicians to envision a voter's car being struck by a train at a crossing and dragged for 500 miles, since there was no engineer to see it happen.

WC's response was that it was already running automated freight trains in New Zealand with no problems because they had cameras on board.

It then mentioned that with automated trains, it could run more trains closer together. If you've ever lived near a railroad, whether small town or big city, stalled freight trains blocking grade crossings are a major problem. So the little towns didn't like hearing that automation meant more trains.

I don't know what the status is today, but by the time I left the midwest, WC had instead shelled out the money to upgrade the tracks and grade crossings through the little towns so that it could plow trains through without slowing down, achieving the efficiency it was looking for, without resorting to automation.

Wisconsin Central was my local railroad growing up, and they've since been bought out by Canadian National (in 2001). When I look at documentary footage from the 90s or before of trains coming through my town it's obvious how much effort they put into upgrading the tracks and removing as many grade crossings as they could. Driving a few extra blocks to get to a crossing was annoying when I lived on the other side of the tracks, but I can definitely appreciate the improved safety and increased speed of the trains compared to when Wisconsin Central originally took over the rickety old Chicago Nortwestern (/Fox River Valley RR) and Soo trackage. CN can speed trains through town at 35MPH so it's not usually too long of a wait.

How does this negate the efficiency from slack? Each bogie is sized to move one car and all the cars move independently. Isn’t that effectively slack? Unlike regular freight trains, it wouldn’t have the momentum of all cars in front helping to start any given car, but on the other hand, that momentum was still produced by the locomotive earlier in the starting of the train.

I think it's around like a ton of goods for 500 miles, per gallon of fuel.

is MOE maintenance of equipment and MOW maintenance of way?

I thought the big inefficiency of rail was not physics, but capitalism and competition.

the cost of starting a trucking company is negligible and a truck can immediately use the shared resource roadway.

Meanwhile use of a railway system is governed by a central authority and shipping is not subject to competition in the same way. Additionally long segments of single-rail prevent efficient use of routes

Would be interesting if there was a two-way (two or more tracks) railway system where trains could hop on and hop off on a first-come first-served basis...

Reply on news.ycombinator.com