5 ms·

Anyone able to comment on why 30km hour was targeted for the high capacity lanes? Given system is automated, would think higher speeds would be targeted, espec

Anyone able to comment on why 30km hour was targeted for the high capacity lanes? Given system is automated, would think higher speeds would be targeted, especially given the system is within tunnels. Simple math without knowing more would suggest 60km would be 2x more, 120km 4x more. __ Edit: Here are prior HN comments 57-days ago on a different article: https://news.ycombinator.com/item?id=31204168 https://news.ycombinator.com/item?id=31204168 __ Edit-2: Here’s a map to that provides a idea of how the population is spread out in the country: https://upload.wikimedia.org/wikipedia/commons/9/9b/Städtischen_Bevölkerung_Schweiz_2019_de.png https://upload.wikimedia.org/wikipedia/commons/9/9b/Städtisc...

imtringued 4y ago
That is not simple math, that is lying by omission. Trucks only drive 80km/h so talking about 120km/h either makes you sound like an elementary schooler or an Elon Musk fanboy.
genocidicbunny 4y ago
Just a guess, but maybe it's just a good starting point. 30kmh is pretty quick for moving goods (if you factor in all the downtime that goods spend in warehouses) and is also not terribly hard to deal with in terms of designing the system and the traction engines. When you combine this with the fact that the density can be higher than with human drivers, 30kmh doesn't seem so bad. Plus I would think they could gradually increase the speed as the system proves itself more. There are so many other challenges with getting this done, that maybe making the system go as fast as possible took a backburner.
- caseyf7 4y ago
  There will also be significant elevation changes
  - genocidicbunny 4y ago
    There will be, but seeing as this is a tunnel system, those elevation changes can be spread out a lot more than they would be if this was overland. I'm sure it's _a_ factor, but not likely to be the biggest factor in the max speed.
  - _nalply 4y ago
    Bern is at 550 m (1800 feet) and Basel at 260 m (850 feet). I don't think that elevation changes matter a lot.
- config_yml 4y ago
  Maybe also packing efficiency. Cargo has to be less rigid and secured, more diverse load types etc.
colmmacc 4y ago
I know nothing about this project and probably shouldn't comment but from previous logistics projects I've worked on I've learned that maintenance costs from wear and tear all seem to increase non-linearly with mechanical speed. An everyday example is that some buildings choose to run their elevators at slower speeds for this reason, but the speeds of industrial and logistical conveyor belts are carefully chosen with this in mind too. Of course air resistance also goes up non-linearly with speed, and that might be a factor here.
cperciva 4y ago
They're probably optimizing for consistent throughout rather than latency. Faster vehicles would reduce latency but increases the risk that a breakdown would knock out some of the capacity. (And with an underground network it's not so easy to pull off onto a side street!)
devoutsalsa 4y ago
Is there any benefit to going faster? 30km/hour gets you anywhere in Switzerland in less than 24 hours.
- jjallen 4y ago
  More throughput would be a benefit. Not saying they should; just responding directly to this question.
  - bobthepanda 4y ago
    Yes and no. Safe deceleration must be accounted for in these projects. It‘s a lot faster to safely decelerate at 30kph than say 80kph.
  - prmoustache 4y ago
    More throughput means more storage space needed at destination or faster loading / offloading speed and more local delivery rotation which won't be possible in final destination.
ahi 4y ago
From some googling, average freight speed in the US is under 40km hour. And that includes huge stretches of track without a curve or a mole hill. The capacity limitations end up at the depots anyway so going faster just means hurry up and wait.
- O__________O 4y ago
  Systems are not comparable. US systems are to my knowledge: all above ground; long trains, which require longer stopping distances; require manual loading; coupling of trains is manual; driven by humans; distances traveled are completely different; one-way, single direction, per use; breakdown cannot be routed around; etc.
sandworm101 4y ago
Its all about energy. Accelerating the cars up to speed is one thing, but slowing them down and negotiating corners is another. Whether you use batteries or diesel, speed always takes more energy. As for throughput, we need to know the safe distance between these things at various speeds. Just like on roadways, they need to be able to stop if the car/train ahead of them stops. So slower cars, closer together, probably result in more cars passing per second than at higher speeds with greater stopping distances between cars. Exactly the same as with roads. Anyone who thinks that because these things are automated that they can safely travel bumper-to-bumper at high speeds hasn't worked with vehicles underground before. Any pileup in a tunnel is a nightmare. Something burning, especially something high-energy like butter or flour, turns the tunnel into a blast furnace. Safety distances will always be required. https://en.wikipedia.org/wiki/Mont_Blanc_tunnel_fire https://en.wikipedia.org/wiki/Mont_Blanc_tunnel_fire >>On the morning of 24 March 1999, 39 people died when a Belgian transport truck carrying flour and margarine, which had entered the French-side portal, caught fire in the tunnel.
- jakear 4y ago
  > So slower cars, closer together, probably result in more cars passing per second than at higher speeds with greater stopping distances between cars. Exactly the same as with roads. I hear this from time to time but it doesn’t pass the sniff test. If we assume the vehicles are points, their flow is precisely determined by stopping distance (as measured in seconds). If on the other hand we assume the vehicles are very long, their flow is determined by speed. Thus flow at minimum does not change with respect to speed, but in practice increases with respect to speed, assuming time-constant stopping distances (i.e. you pass X point Y seconds after the vehicle in front of you does)
  - Retric 4y ago
    First friction limited stopping distance is a function of Velocity squared. Trains running on rails are longer, but the reason they use rails is rails have lower friction. Which is why real world freight trains have stopping distances at 65MPh of over a mile. This is also one of the reasons they can’t climb seemingly mild inclines. Limiting the underground freight trains to say 1/10th a mile and maximum throughput is probably close to 30mph.
jjallen 4y ago
I was also suprised they couldn't go faster. Maybe energy efficiency? That is the only reason you would go slower. Maybe they are trying to make this thing hyper-efficient energy wise. But this project is awesome for two reasons: one, I've always wondered why this sort of thing isn't automated. We could even have humans moving small packages intra-city underground on conveyor belts. And two, I live in Zurich, so being close to what I believe is the first project of this type ever, is super cool.
- bobthepanda 4y ago
  There used to be pneumatic (compressed air) tubes for mail, but it became kind of irrelevant when fax and email obviated the need to send small letters.
  - semi-extrinsic 4y ago
    They're still popular in hospitals AFAIK, where they are useful for sending e.g. blood samples and medicines around.
- thematrixturtle 4y ago
  First after the Alameda-Weehawken Burrito Tunnel, of course. https://idlewords.com/2007/04/the_alameda_weehawken_burrito_tunnel.htm https://idlewords.com/2007/04/the_alameda_weehawken_burrito_...
vegai_ 4y ago
Based on my extensive experience on factory building games I would suggest that perhaps also in real world wreight transfer, latency doesn't matter, only throughput.
tonfa 4y ago
It seems to be last mile distribution from logistical centers, so targeting rather short distances given the size of the country and distribution of large cities. First segment is between on of the biggest logistical hub and Zurich (largest city), which are 70km apart.
komposit 4y ago
Given this is goods and not people the more relevant metric is not the average speed of the carts but the volumetric flow rate at each of the nodes in this system.
_nalply 4y ago
Imagine you ordered something from Amazon. It will take about 24 hours till it is at your doorstep. If all that time was spent travelling at 30 km/h, it could have come from 720 km or 450 miles. In Switzerland, the distance from Geneva to St. Gall is around 360 km. Container ships travel typically at 16 to 25 knots (between 30 and 36 km/h), and they do this traveling very long distances. In other words, low speed does not really matter for many goods, especially in small countries.
- aenis 4y ago
  Also, its the average speed that counts. I doubt the avg speed of a freight truck running between two relatively close swiss cities exceeds 50km/h. Avg speeds drop sharply with any stops or slowdowns.
adhesive_wombat 4y ago
The total throughout (in cars/hour) is given by speed divided by effective length. Effective length is the length of a carriage plus its share of the distance between trains, which is something like quadratic in speed (since kinetic energy also is) So the total result is something (caution, probably there are other factors here, such as non-carrying cars like locomotives) like: v TP = ---------- Kv^2 L + ---- N Where TP is throughput, v is speed, L is car length, N is cars per train and K is some constant that determines the head between trains. To maximise throughput, you can't just crank up speed as you start to dominate the line with space between trains (as kV^2 grows). There will be a sweet spot when it is optimum. This applies as long as the braking distance of a train is super-linear, actually, so even if the distance is not quadratic in speed, say it was Kv^1.5, it still holds. You can make trains longer (increase N) to reduce the number of spaces between trains. But this has its own practical issues. You can also decrease K with better brakes or sensors that allow to brake earlier. But I imagine there's either a practical limit like forces on the tracks or trains, cost too much, or trains have what they have and can't be upgraded. You can also make cars hold more per unit length, but that's also difficult in a fixed guage in tunnels. Finally, if you're running trains as close as you can, there's no point running faster then the slowest train in the system. If a train at any point has to slow to 30kph, say for a corner or climb, that's the speed of the whole line.
ur-whale 4y ago
> Anyone able to comment on why 30km hour was targeted for the high capacity lanes? Maybe because it's a good start? And what matters for a project like this is throughput, of which speed is but a single component, uninterrupted flow and volume being others.

imtringued 4y ago

That is not simple math, that is lying by omission. Trucks only drive 80km/h so talking about 120km/h either makes you sound like an elementary schooler or an Elon Musk fanboy.

genocidicbunny 4y ago

Just a guess, but maybe it's just a good starting point. 30kmh is pretty quick for moving goods (if you factor in all the downtime that goods spend in warehouses) and is also not terribly hard to deal with in terms of designing the system and the traction engines. When you combine this with the fact that the density can be higher than with human drivers, 30kmh doesn't seem so bad. Plus I would think they could gradually increase the speed as the system proves itself more. There are so many other challenges with getting this done, that maybe making the system go as fast as possible took a backburner.

caseyf7 4y ago
There will also be significant elevation changes
- genocidicbunny 4y ago
  There will be, but seeing as this is a tunnel system, those elevation changes can be spread out a lot more than they would be if this was overland. I'm sure it's _a_ factor, but not likely to be the biggest factor in the max speed.
- _nalply 4y ago
  Bern is at 550 m (1800 feet) and Basel at 260 m (850 feet). I don't think that elevation changes matter a lot.
config_yml 4y ago
Maybe also packing efficiency. Cargo has to be less rigid and secured, more diverse load types etc.

colmmacc 4y ago

I know nothing about this project and probably shouldn't comment but from previous logistics projects I've worked on I've learned that maintenance costs from wear and tear all seem to increase non-linearly with mechanical speed. An everyday example is that some buildings choose to run their elevators at slower speeds for this reason, but the speeds of industrial and logistical conveyor belts are carefully chosen with this in mind too. Of course air resistance also goes up non-linearly with speed, and that might be a factor here.

cperciva 4y ago

They're probably optimizing for consistent throughout rather than latency. Faster vehicles would reduce latency but increases the risk that a breakdown would knock out some of the capacity. (And with an underground network it's not so easy to pull off onto a side street!)

devoutsalsa 4y ago

Is there any benefit to going faster? 30km/hour gets you anywhere in Switzerland in less than 24 hours.

jjallen 4y ago
More throughput would be a benefit. Not saying they should; just responding directly to this question.
- bobthepanda 4y ago
  Yes and no. Safe deceleration must be accounted for in these projects. It‘s a lot faster to safely decelerate at 30kph than say 80kph.
- prmoustache 4y ago
  More throughput means more storage space needed at destination or faster loading / offloading speed and more local delivery rotation which won't be possible in final destination.

ahi 4y ago

From some googling, average freight speed in the US is under 40km hour. And that includes huge stretches of track without a curve or a mole hill. The capacity limitations end up at the depots anyway so going faster just means hurry up and wait.

O__________O 4y ago
Systems are not comparable. US systems are to my knowledge: all above ground; long trains, which require longer stopping distances; require manual loading; coupling of trains is manual; driven by humans; distances traveled are completely different; one-way, single direction, per use; breakdown cannot be routed around; etc.

sandworm101 4y ago

Its all about energy. Accelerating the cars up to speed is one thing, but slowing them down and negotiating corners is another. Whether you use batteries or diesel, speed always takes more energy. As for throughput, we need to know the safe distance between these things at various speeds. Just like on roadways, they need to be able to stop if the car/train ahead of them stops. So slower cars, closer together, probably result in more cars passing per second than at higher speeds with greater stopping distances between cars. Exactly the same as with roads. Anyone who thinks that because these things are automated that they can safely travel bumper-to-bumper at high speeds hasn't worked with vehicles underground before. Any pileup in a tunnel is a nightmare. Something burning, especially something high-energy like butter or flour, turns the tunnel into a blast furnace. Safety distances will always be required. https://en.wikipedia.org/wiki/Mont_Blanc_tunnel_fire https://en.wikipedia.org/wiki/Mont_Blanc_tunnel_fire >>On the morning of 24 March 1999, 39 people died when a Belgian transport truck carrying flour and margarine, which had entered the French-side portal, caught fire in the tunnel.

jakear 4y ago
> So slower cars, closer together, probably result in more cars passing per second than at higher speeds with greater stopping distances between cars. Exactly the same as with roads. I hear this from time to time but it doesn’t pass the sniff test. If we assume the vehicles are points, their flow is precisely determined by stopping distance (as measured in seconds). If on the other hand we assume the vehicles are very long, their flow is determined by speed. Thus flow at minimum does not change with respect to speed, but in practice increases with respect to speed, assuming time-constant stopping distances (i.e. you pass X point Y seconds after the vehicle in front of you does)
- Retric 4y ago
  First friction limited stopping distance is a function of Velocity squared. Trains running on rails are longer, but the reason they use rails is rails have lower friction. Which is why real world freight trains have stopping distances at 65MPh of over a mile. This is also one of the reasons they can’t climb seemingly mild inclines. Limiting the underground freight trains to say 1/10th a mile and maximum throughput is probably close to 30mph.

jjallen 4y ago

I was also suprised they couldn't go faster. Maybe energy efficiency? That is the only reason you would go slower. Maybe they are trying to make this thing hyper-efficient energy wise. But this project is awesome for two reasons: one, I've always wondered why this sort of thing isn't automated. We could even have humans moving small packages intra-city underground on conveyor belts. And two, I live in Zurich, so being close to what I believe is the first project of this type ever, is super cool.

bobthepanda 4y ago
There used to be pneumatic (compressed air) tubes for mail, but it became kind of irrelevant when fax and email obviated the need to send small letters.
- semi-extrinsic 4y ago
  They're still popular in hospitals AFAIK, where they are useful for sending e.g. blood samples and medicines around.
thematrixturtle 4y ago
First after the Alameda-Weehawken Burrito Tunnel, of course. https://idlewords.com/2007/04/the_alameda_weehawken_burrito_tunnel.htm https://idlewords.com/2007/04/the_alameda_weehawken_burrito_...

vegai_ 4y ago

Based on my extensive experience on factory building games I would suggest that perhaps also in real world wreight transfer, latency doesn't matter, only throughput.

tonfa 4y ago

It seems to be last mile distribution from logistical centers, so targeting rather short distances given the size of the country and distribution of large cities. First segment is between on of the biggest logistical hub and Zurich (largest city), which are 70km apart.

komposit 4y ago

Given this is goods and not people the more relevant metric is not the average speed of the carts but the volumetric flow rate at each of the nodes in this system.

_nalply 4y ago

Imagine you ordered something from Amazon. It will take about 24 hours till it is at your doorstep. If all that time was spent travelling at 30 km/h, it could have come from 720 km or 450 miles. In Switzerland, the distance from Geneva to St. Gall is around 360 km. Container ships travel typically at 16 to 25 knots (between 30 and 36 km/h), and they do this traveling very long distances. In other words, low speed does not really matter for many goods, especially in small countries.

aenis 4y ago
Also, its the average speed that counts. I doubt the avg speed of a freight truck running between two relatively close swiss cities exceeds 50km/h. Avg speeds drop sharply with any stops or slowdowns.

adhesive_wombat 4y ago

The total throughout (in cars/hour) is given by speed divided by effective length. Effective length is the length of a carriage plus its share of the distance between trains, which is something like quadratic in speed (since kinetic energy also is) So the total result is something (caution, probably there are other factors here, such as non-carrying cars like locomotives) like: v TP = ---------- Kv^2 L + ---- N Where TP is throughput, v is speed, L is car length, N is cars per train and K is some constant that determines the head between trains. To maximise throughput, you can't just crank up speed as you start to dominate the line with space between trains (as kV^2 grows). There will be a sweet spot when it is optimum. This applies as long as the braking distance of a train is super-linear, actually, so even if the distance is not quadratic in speed, say it was Kv^1.5, it still holds. You can make trains longer (increase N) to reduce the number of spaces between trains. But this has its own practical issues. You can also decrease K with better brakes or sensors that allow to brake earlier. But I imagine there's either a practical limit like forces on the tracks or trains, cost too much, or trains have what they have and can't be upgraded. You can also make cars hold more per unit length, but that's also difficult in a fixed guage in tunnels. Finally, if you're running trains as close as you can, there's no point running faster then the slowest train in the system. If a train at any point has to slow to 30kph, say for a corner or climb, that's the speed of the whole line.

ur-whale 4y ago

> Anyone able to comment on why 30km hour was targeted for the high capacity lanes? Maybe because it's a good start? And what matters for a project like this is throughput, of which speed is but a single component, uninterrupted flow and volume being others.