7 ms·

The only industry to have produced truly driverless public transportation systems is the rail industry. Not aeronautics. Rail systems happens to be my business

by crocal 9y ago

The only industry to have produced truly driverless public transportation systems is the rail industry. Not aeronautics. Rail systems happens to be my business and what I read here makes me very worried. I don't think the majority understands what safety means in mass transportation. It's not about running miles and miles without accidents and basically saying "see"? It's about demonstrating /by design/ that the /complete/ system over its /complete/ lifetime will not kill anyone. In terms of probability of failure it translates in demonstrated hazard rates of less than 1E-9 /including the control systems/. This take very special techniques and if that could've been done using only vehicle sensors, it would have been adopted by us long ago. I am also sorry to report that doubling cameras and sensor fusion will not get you an acceptable safety level. We've tried that too, rookies. Is it "fair", to use Elon's argument? After all, isn't additional safety enough compared to existing situation. Ah but we have been there too! For driver assistance it is indeed better. Similar systems were deployed during the second half of 20th century (e.g. KVB, ASFA, etc). But the limit is clear. It only /improves/ driver's failure rate. It does not substitute for the driver. If you substitute, you have to do much much much better. Nobody will ride a driverless vehicle provided the explanation that it is, you know, "already an improvement when compared to a typical driver". Is it fair? Maybe not, but that's the whole point for entrusting lives to a machine.

tyrw 9y ago
It seems like you're taking your own opinion as a universal truth. There are many people (myself included) who will happily ride in a well-tested autonomous vehicle, particularly if the alternative is a taxi, uber, or bus driver who is just going through the motions. 5x safer is still an improvement in my eyes, even if it's still short of the gold standard for aviation.
- crocal 9y ago
  No personal opinion here. It's just facts from the only ones around who have done this before. Your argument is flawed. We have also been there. Here is the catch. You are willing to take the risk, but society as a whole will not. As soon as you release /total/ control to a machine, public authorities having authorized this become responsible for your life and those your car may threaten. Requirements for said authorities to accept such things will be staggering. In other words, it is you that is taking your own opinion for the universal truth. You reason in a model where the driver is the only responsible party for reckless driving.
  - network_ops 9y ago
    facts? Do you have sources?
    - crocal 9y ago
      The requirements for safety in railway are well defined in EN 50129, EN 50126 and EN 50128. You will be required to meet these standards for an ISA (independent safety authority) to give a positive report, and then for the applicable transportation authority to grant revenue service authorization. As you can imagine, the willingness of a given passenger to take a certain amount of risk is not part of the process described in these standards. EDIT: theses standards are applied worldwide, despite the EN prefix. EDIT: good reference site: http://en50126.blogspot.it/2008/07/velkommen.html?m=1 http://en50126.blogspot.it/2008/07/velkommen.html?m=1
  - tyrw 9y ago
    I'd disagree here too. Trains and planes have extremely catastrophic failure modes, while cars do not. Cars have the added benefit of being able to quickly come to a stop in most situations. An even bigger driving factor (pun intended) will be that the cost of a driver relative to operation is much, much higher in a car. A solution that is better on both safety and cost will be quickly adopted.
    - crocal 9y ago
      For the first paragraph, I don't understand the logic behind your comparison between a train failure mode and a car failure mode. However your assumption on braking capability is wrong and it is a crucial point. It does not matter how well your car can brake. Can your autonomous driving system guarantee it will always brake as hard and as fast as required when you will need it? Can you guarantee that the system will not have a bug the day it needs to brake? Trains brake very well. There are even rubber wheel metros that brake so well we have to limit them in order not to sent everyone flying in the wagons :). But in the safety calculations, standards like IEEE 1474 assumes degraded braking capability, and also considers that the preceding train is at stop. In other words, to be declared safe for mass usage, you can't assume average case. You must assume adverse case. You will not have a driver to notice that the car brakes poorly or to be confident enough to drive very close to the preceding car. For the second paragraph, again, this is certainly true for driving assistance, but will most likely not be enough for driverless, as it was / is not enough for trains. Of course you may disagree. EDIT: this is a good reference: https://www.linkedin.com/pulse/safe-braking-model-explained-naeem-ali-p-eng https://www.linkedin.com/pulse/safe-braking-model-explained-...
RoyTyrell 9y ago
I'm not saying you're wrong, because I have absolutely no authority in the subject, but apart from knowing some terminology how do we know you have any expertise either? > If you substitute, you have to do much much much better. Nobody will ride a driverless vehicle provided the explanation that it is, you know, "already an improvement when compared to a typical driver". Is it fair? Maybe not, but that's the whole point for entrusting lives to a machine. I've heard Elon mention this and while I don't know exactly it's measured, he claimed that fully autonomous cars would have to be 10x "better" at driving than a human before they would be allowed. I'm paraphrasing when I say "better" but I'm sure I could find the video of him talking about it. At any rate, your comment is interesting.
- crocal 9y ago
  You are correct. I will edit and add some supporting references. I don't know where Elon gets his numbers from, but according to EN 50126 practioners, human error is in the range of 2E-4 / 1E-3 whereas safety functions are classified at least SIL2 and that means 1E-6. In other word, the system must be x1000 better than a human. Here is a good reference: http://en50126.blogspot.it/2009/10/safety-integrity-levels-sil.html?m=1 http://en50126.blogspot.it/2009/10/safety-integrity-levels-s...
gervase 9y ago
I think the mapping between rail and motor vehicle transportation is not necessarily a direct one. Rail (excluding public transit like subway) is more infrastructural and largely unseen, and cars are basically a daily experience for the majority of the population; this fundamentally changes people's perceptions of each. > Nobody will ride a driverless vehicle provided the explanation that it is, you know, "already an improvement when compared to a typical driver". I don't necessarily think this is true (perhaps age-correlated?). Let's set aside the issue of whether or not we can do it, for now, and assume that we have a scenario where self-driving cars are safer than human drivers. In this context, I can easily imagine a political campaign à la "Think of the children!" that paints human drivers as fundamentally unsafe, advocating for a self-driving mandate in urban areas. Perhaps with a Cash-for-Clunkers type of deal to aid the transition. I am not saying this is desirable, merely plausible; it has all the elements of good politics: an easily-grasped bright-line dichotomy, emotional manipulation, and massive corporate benefits (for vehicle manufacturers, self-driving software vendors, and transportation providers like Uber).
- crocal 9y ago
  Driverless trains so far are only used in mass transit so... I am afraid these are daily experience. For the second part of your argument, there are multiple problems, again backed by examples in the railway world. First, a politician will think twice before casting a devilish image of drivers. Having all the professional drivers against you is essentially a political hara-kiri. There is a reason why it took 10 years to migrate Paris Line 1 to driverless, and it is not technology. Second, you would not believe how difficult it is to reach consensus on the fact that drivers are unsafe compared to a machine. Still today, even after decades of operations with no incident, there are still people in the industry that argue otherwise... The most telling example is the high speed derailment in Santiago de Compostela, essentially due to the fact that the driver is considered a good enough guarantee to drive a high speed passenger train up to 200 KPH... Sigh. EDIT: References [1] https://www.witpress.com/Secure/elibrary/papers/9781845644949/9781845644949006FU1.pdf https://www.witpress.com/Secure/elibrary/papers/978184564494... [2] https://en.m.wikipedia.org/wiki/Santiago_de_Compostela_derailment https://en.m.wikipedia.org/wiki/Santiago_de_Compostela_derai...
CodeWriter23 9y ago
All due respect to your experience with the rail industry and its impressively high bar for safety, in the auto industry, if they can get the death rate down to 48 people killed every day in the US, that will be twice as safe as we are currently.
- crocal 9y ago
  Sure, and this goal can be reached without driverless. I am really supportive of driver assistance. The point I try to make is that bringing driverless on top is a challenge that seems to be underestimated.
maxcan 9y ago
You think the rail industry understands what safety means? Trains have literally one degree of freedom in their controls - speed up and slow down. In spite of the simplicity we still see high fatality train crashes with regularity. Some how sticking people in a paper thin aluminum tube 6 miles up going 600mph can be done with zero fatalities but we can't get trains to stop killing people. I'm ranting here, but you're on an undeservedly high horse.
- crocal 9y ago
  No problem at all, I was half expecting such reaction. http://www.uitp.org/sites/default/files/Metro%20automation%20-%20facts%20and%20figures.pdf http://www.uitp.org/sites/default/files/Metro%20automation%2... There has been 1 accident in 30 years attributed to driverless rail mass transit control system, despite millions of kilometers travelled and a constant worldwide growth. Yes, rail has understood what driverless safety means. You may call it a high horse but driverless /is/ a high horse. That's my point. In a way, your comment confirms this success. You think it is easy because you are used to it at an instinctive level. And that is the goal, precisely. But it is not as simple as what you imagine. For instance, trains have multiple degree of freedoms. As an illustration, train builders calculate carefully the dynamic enveloppe of the cars (e.g. its worst lateral deformation due to bogie flexibility) and check against the tunnel walls geometry. http://www.railsystem.net/structure-gauge-and-kinematic-envelope/ http://www.railsystem.net/structure-gauge-and-kinematic-enve...
  - kerbalspacepro 9y ago
    Are we talking about metros or trains? Metros are built out of the way. They shouldn't kill people because there are a few stations of track that they can kill people. The second you put the train in the open air where other people are, where weather is, where nature is, those things kill people on the regular. Get out of your tunnel, and suddenly your "success" has nothing to do with the control system.
    - crocal 9y ago
      Metros are the only driverless systems in mass transit so far. There are some ongoing projects for driverless freight but I consider that it is not relevant to this particular discussion. I don't want to sound obnoxious but driverless metros routinely operate in the open air :). Tunnels are not a mandatory condition for such systems. They manage strong winds, strong rains with reduced adhesion conditions, etc. They manage the possibility for people or non-protected trains to intrude on the track. A lot of brain was put into automating decisions related to fire scenarios or emergency evacuations. Metro lines like Paris line 1 are extremely busy. There are plenty of ways to kill people, yet they don't. Just the "stuck hand-bag" scenario is a nightmare to manage. Yet. A driverless system is truly a massive piece of software. You guys should come in the tunnels and have fun with us!
oh_sigh 9y ago
> This take very special techniques and if that could've been done using only vehicle sensors, it would have been adopted by us long ago If human flight was possible, surely they would have done it hundreds or thousands of years ago. Your argument disregards not only advancement in theoretical knowledge, but also advancement engineering in the form of computational power and sensor sensitivity.
- crocal 9y ago
  You confuse technological advances and safety techniques. These are very different things. Safety techniques are theoretical principles that are used to keep technology safe. Typical examples of safety techniques in systems design are: readback, diversity, majority voting, coding of information. In the case of establishing the correct position of vehicles, whatever the technology used it will have an error of measurement. This error accumulates over time, especially if you are measuring displacement. You will need reference points to retain your positional uncertainty within an acceptable value. An autonomous vehicle uses a map containing features that can be used as reference points and triangulate its position based on that. A human brain does this constantly using its eyes, ears and memory. It is an example of diversity: you correlate the perceived displacement by your internal ear with what your eyes sees, using a reference learned in your brain about your surroundings and sensors' ability. To reach 1E-9, we cannot rely on such self-learned things: we can agree that the probability for the landscape to change is quite higher than 1E-9. In the case of trains, driverless trains use coded beacons / loops or GPS diversity. Such techniques imply that the infrastructure around your vehicle collaborates to the safety of the system. Hence my statement. This being said, the rail industry has been dreaming for long of a completely vehicle centric solution. There are high stakes for that: reduced costs, competitive advantage, etc. Last attempt here: http://www.alstom.com/products-services/product-catalogue/rail-systems/signalling/products/urbalis-fluence/ http://www.alstom.com/products-services/product-catalogue/ra...
cameldrv 9y ago
This is a good summary of modern risk culture. It has good sides and bad sides. On the good side, you have things like commercial aircraft and trains that, despite them being inherently dangerous, manage to achieve extremely low fatality rates. On the bad side, this risk culture destroys large scale innovation, and even safety in the long run. The problem is that we've adopted an attitude that safety is always first, meaning that it is immoral to do something in a less safe way, no matter what the other benefits might be. This means we get a regulatory, tort, and engineering culture that is willing to use existing systems, because they are grandfathered and therefore "reasonable", but will only adopt new systems if they can be shown to be perfectly safe. This culture is fairly new. I date it to sometime in the seventies. Ralph Nader and the Pinto were both symptoms and causes. You can see the transition in, for example, how America responded to the Apollo 1 fire vs. the Challenger accident. Since you're a a rail engineer, let's look at rail mass transit systems. The NYC subway has a limit of roughly 30 trains per hour, a two minute headways. All of the braking rates, margins of safety, and signaling systems do their job, and you never see two trains hitting each other. During rush hour though, trains are packed way over capacity, and this is mostly because of this headway limitation. If you were to imagine this on the freeway, you'd have to leave two miles between you and the next car. The cost for this level of safety is that about half a million people have to spend an hour every day in miserable conditions. Many of them choose to drive or take cabs instead, to avoid this. When they make this decision, none of them even give the slightest thought that driving is maybe 10x more dangerous than taking the train. They understand that safety for both is plenty good, and the way that they spend two hours of their day, 13% of their waking hours, is a lot more important than some tiny difference in their risk of dying on the way to work. Ultimately, while very well intentioned, this safety culture is inhuman. It's pessimistic. It says "nothing in your life could possibly be so important that it's worth any possibility of you being injured. " So, this is what we face now, over and over. With self driving cars, it's, "sure, the chance of you getting killed is half as much as if you had driven, plus you get all of that time back to have a nice conversation, read a book, or idly stare out the window, but since it doesn't meet our aviation/rail transit level of safety, you can't have it." You even see it with kids -- your twelve year old kids can't be allowed out of the sight of an adult, or you're a dangerous, neglectful parent. It does not matter that childhood is the process of learning how to be an adult, and that becoming an adult is a process of progressively mastering greater and greater freedoms -- the most important thing is that we are never seen to expose children to even the most minute level of risk. I really want us to have a real conversation about acceptable risk, informed consent, and human progress. We need it badly to regain our souls.

by crocal 9y ago

tyrw 9y ago

It seems like you're taking your own opinion as a universal truth. There are many people (myself included) who will happily ride in a well-tested autonomous vehicle, particularly if the alternative is a taxi, uber, or bus driver who is just going through the motions. 5x safer is still an improvement in my eyes, even if it's still short of the gold standard for aviation.

crocal 9y ago
No personal opinion here. It's just facts from the only ones around who have done this before. Your argument is flawed. We have also been there. Here is the catch. You are willing to take the risk, but society as a whole will not. As soon as you release /total/ control to a machine, public authorities having authorized this become responsible for your life and those your car may threaten. Requirements for said authorities to accept such things will be staggering. In other words, it is you that is taking your own opinion for the universal truth. You reason in a model where the driver is the only responsible party for reckless driving.
- network_ops 9y ago
  facts? Do you have sources?
  - crocal 9y ago
    The requirements for safety in railway are well defined in EN 50129, EN 50126 and EN 50128. You will be required to meet these standards for an ISA (independent safety authority) to give a positive report, and then for the applicable transportation authority to grant revenue service authorization. As you can imagine, the willingness of a given passenger to take a certain amount of risk is not part of the process described in these standards. EDIT: theses standards are applied worldwide, despite the EN prefix. EDIT: good reference site: http://en50126.blogspot.it/2008/07/velkommen.html?m=1 http://en50126.blogspot.it/2008/07/velkommen.html?m=1
- tyrw 9y ago
  I'd disagree here too. Trains and planes have extremely catastrophic failure modes, while cars do not. Cars have the added benefit of being able to quickly come to a stop in most situations. An even bigger driving factor (pun intended) will be that the cost of a driver relative to operation is much, much higher in a car. A solution that is better on both safety and cost will be quickly adopted.
  - crocal 9y ago
    For the first paragraph, I don't understand the logic behind your comparison between a train failure mode and a car failure mode. However your assumption on braking capability is wrong and it is a crucial point. It does not matter how well your car can brake. Can your autonomous driving system guarantee it will always brake as hard and as fast as required when you will need it? Can you guarantee that the system will not have a bug the day it needs to brake? Trains brake very well. There are even rubber wheel metros that brake so well we have to limit them in order not to sent everyone flying in the wagons :). But in the safety calculations, standards like IEEE 1474 assumes degraded braking capability, and also considers that the preceding train is at stop. In other words, to be declared safe for mass usage, you can't assume average case. You must assume adverse case. You will not have a driver to notice that the car brakes poorly or to be confident enough to drive very close to the preceding car. For the second paragraph, again, this is certainly true for driving assistance, but will most likely not be enough for driverless, as it was / is not enough for trains. Of course you may disagree. EDIT: this is a good reference: https://www.linkedin.com/pulse/safe-braking-model-explained-naeem-ali-p-eng https://www.linkedin.com/pulse/safe-braking-model-explained-...

RoyTyrell 9y ago

I'm not saying you're wrong, because I have absolutely no authority in the subject, but apart from knowing some terminology how do we know you have any expertise either? > If you substitute, you have to do much much much better. Nobody will ride a driverless vehicle provided the explanation that it is, you know, "already an improvement when compared to a typical driver". Is it fair? Maybe not, but that's the whole point for entrusting lives to a machine. I've heard Elon mention this and while I don't know exactly it's measured, he claimed that fully autonomous cars would have to be 10x "better" at driving than a human before they would be allowed. I'm paraphrasing when I say "better" but I'm sure I could find the video of him talking about it. At any rate, your comment is interesting.

crocal 9y ago
You are correct. I will edit and add some supporting references. I don't know where Elon gets his numbers from, but according to EN 50126 practioners, human error is in the range of 2E-4 / 1E-3 whereas safety functions are classified at least SIL2 and that means 1E-6. In other word, the system must be x1000 better than a human. Here is a good reference: http://en50126.blogspot.it/2009/10/safety-integrity-levels-sil.html?m=1 http://en50126.blogspot.it/2009/10/safety-integrity-levels-s...

gervase 9y ago

I think the mapping between rail and motor vehicle transportation is not necessarily a direct one. Rail (excluding public transit like subway) is more infrastructural and largely unseen, and cars are basically a daily experience for the majority of the population; this fundamentally changes people's perceptions of each. > Nobody will ride a driverless vehicle provided the explanation that it is, you know, "already an improvement when compared to a typical driver". I don't necessarily think this is true (perhaps age-correlated?). Let's set aside the issue of whether or not we can do it, for now, and assume that we have a scenario where self-driving cars are safer than human drivers. In this context, I can easily imagine a political campaign à la "Think of the children!" that paints human drivers as fundamentally unsafe, advocating for a self-driving mandate in urban areas. Perhaps with a Cash-for-Clunkers type of deal to aid the transition. I am not saying this is desirable, merely plausible; it has all the elements of good politics: an easily-grasped bright-line dichotomy, emotional manipulation, and massive corporate benefits (for vehicle manufacturers, self-driving software vendors, and transportation providers like Uber).

crocal 9y ago
Driverless trains so far are only used in mass transit so... I am afraid these are daily experience. For the second part of your argument, there are multiple problems, again backed by examples in the railway world. First, a politician will think twice before casting a devilish image of drivers. Having all the professional drivers against you is essentially a political hara-kiri. There is a reason why it took 10 years to migrate Paris Line 1 to driverless, and it is not technology. Second, you would not believe how difficult it is to reach consensus on the fact that drivers are unsafe compared to a machine. Still today, even after decades of operations with no incident, there are still people in the industry that argue otherwise... The most telling example is the high speed derailment in Santiago de Compostela, essentially due to the fact that the driver is considered a good enough guarantee to drive a high speed passenger train up to 200 KPH... Sigh. EDIT: References [1] https://www.witpress.com/Secure/elibrary/papers/9781845644949/9781845644949006FU1.pdf https://www.witpress.com/Secure/elibrary/papers/978184564494... [2] https://en.m.wikipedia.org/wiki/Santiago_de_Compostela_derailment https://en.m.wikipedia.org/wiki/Santiago_de_Compostela_derai...

CodeWriter23 9y ago

All due respect to your experience with the rail industry and its impressively high bar for safety, in the auto industry, if they can get the death rate down to 48 people killed every day in the US, that will be twice as safe as we are currently.

crocal 9y ago
Sure, and this goal can be reached without driverless. I am really supportive of driver assistance. The point I try to make is that bringing driverless on top is a challenge that seems to be underestimated.

maxcan 9y ago

You think the rail industry understands what safety means? Trains have literally one degree of freedom in their controls - speed up and slow down. In spite of the simplicity we still see high fatality train crashes with regularity. Some how sticking people in a paper thin aluminum tube 6 miles up going 600mph can be done with zero fatalities but we can't get trains to stop killing people. I'm ranting here, but you're on an undeservedly high horse.

crocal 9y ago
No problem at all, I was half expecting such reaction. http://www.uitp.org/sites/default/files/Metro%20automation%20-%20facts%20and%20figures.pdf http://www.uitp.org/sites/default/files/Metro%20automation%2... There has been 1 accident in 30 years attributed to driverless rail mass transit control system, despite millions of kilometers travelled and a constant worldwide growth. Yes, rail has understood what driverless safety means. You may call it a high horse but driverless /is/ a high horse. That's my point. In a way, your comment confirms this success. You think it is easy because you are used to it at an instinctive level. And that is the goal, precisely. But it is not as simple as what you imagine. For instance, trains have multiple degree of freedoms. As an illustration, train builders calculate carefully the dynamic enveloppe of the cars (e.g. its worst lateral deformation due to bogie flexibility) and check against the tunnel walls geometry. http://www.railsystem.net/structure-gauge-and-kinematic-envelope/ http://www.railsystem.net/structure-gauge-and-kinematic-enve...
- kerbalspacepro 9y ago
  Are we talking about metros or trains? Metros are built out of the way. They shouldn't kill people because there are a few stations of track that they can kill people. The second you put the train in the open air where other people are, where weather is, where nature is, those things kill people on the regular. Get out of your tunnel, and suddenly your "success" has nothing to do with the control system.
  - crocal 9y ago
    Metros are the only driverless systems in mass transit so far. There are some ongoing projects for driverless freight but I consider that it is not relevant to this particular discussion. I don't want to sound obnoxious but driverless metros routinely operate in the open air :). Tunnels are not a mandatory condition for such systems. They manage strong winds, strong rains with reduced adhesion conditions, etc. They manage the possibility for people or non-protected trains to intrude on the track. A lot of brain was put into automating decisions related to fire scenarios or emergency evacuations. Metro lines like Paris line 1 are extremely busy. There are plenty of ways to kill people, yet they don't. Just the "stuck hand-bag" scenario is a nightmare to manage. Yet. A driverless system is truly a massive piece of software. You guys should come in the tunnels and have fun with us!

oh_sigh 9y ago

> This take very special techniques and if that could've been done using only vehicle sensors, it would have been adopted by us long ago If human flight was possible, surely they would have done it hundreds or thousands of years ago. Your argument disregards not only advancement in theoretical knowledge, but also advancement engineering in the form of computational power and sensor sensitivity.

crocal 9y ago
You confuse technological advances and safety techniques. These are very different things. Safety techniques are theoretical principles that are used to keep technology safe. Typical examples of safety techniques in systems design are: readback, diversity, majority voting, coding of information. In the case of establishing the correct position of vehicles, whatever the technology used it will have an error of measurement. This error accumulates over time, especially if you are measuring displacement. You will need reference points to retain your positional uncertainty within an acceptable value. An autonomous vehicle uses a map containing features that can be used as reference points and triangulate its position based on that. A human brain does this constantly using its eyes, ears and memory. It is an example of diversity: you correlate the perceived displacement by your internal ear with what your eyes sees, using a reference learned in your brain about your surroundings and sensors' ability. To reach 1E-9, we cannot rely on such self-learned things: we can agree that the probability for the landscape to change is quite higher than 1E-9. In the case of trains, driverless trains use coded beacons / loops or GPS diversity. Such techniques imply that the infrastructure around your vehicle collaborates to the safety of the system. Hence my statement. This being said, the rail industry has been dreaming for long of a completely vehicle centric solution. There are high stakes for that: reduced costs, competitive advantage, etc. Last attempt here: http://www.alstom.com/products-services/product-catalogue/rail-systems/signalling/products/urbalis-fluence/ http://www.alstom.com/products-services/product-catalogue/ra...

cameldrv 9y ago

This is a good summary of modern risk culture. It has good sides and bad sides. On the good side, you have things like commercial aircraft and trains that, despite them being inherently dangerous, manage to achieve extremely low fatality rates. On the bad side, this risk culture destroys large scale innovation, and even safety in the long run. The problem is that we've adopted an attitude that safety is always first, meaning that it is immoral to do something in a less safe way, no matter what the other benefits might be. This means we get a regulatory, tort, and engineering culture that is willing to use existing systems, because they are grandfathered and therefore "reasonable", but will only adopt new systems if they can be shown to be perfectly safe. This culture is fairly new. I date it to sometime in the seventies. Ralph Nader and the Pinto were both symptoms and causes. You can see the transition in, for example, how America responded to the Apollo 1 fire vs. the Challenger accident. Since you're a a rail engineer, let's look at rail mass transit systems. The NYC subway has a limit of roughly 30 trains per hour, a two minute headways. All of the braking rates, margins of safety, and signaling systems do their job, and you never see two trains hitting each other. During rush hour though, trains are packed way over capacity, and this is mostly because of this headway limitation. If you were to imagine this on the freeway, you'd have to leave two miles between you and the next car. The cost for this level of safety is that about half a million people have to spend an hour every day in miserable conditions. Many of them choose to drive or take cabs instead, to avoid this. When they make this decision, none of them even give the slightest thought that driving is maybe 10x more dangerous than taking the train. They understand that safety for both is plenty good, and the way that they spend two hours of their day, 13% of their waking hours, is a lot more important than some tiny difference in their risk of dying on the way to work. Ultimately, while very well intentioned, this safety culture is inhuman. It's pessimistic. It says "nothing in your life could possibly be so important that it's worth any possibility of you being injured. " So, this is what we face now, over and over. With self driving cars, it's, "sure, the chance of you getting killed is half as much as if you had driven, plus you get all of that time back to have a nice conversation, read a book, or idly stare out the window, but since it doesn't meet our aviation/rail transit level of safety, you can't have it." You even see it with kids -- your twelve year old kids can't be allowed out of the sight of an adult, or you're a dangerous, neglectful parent. It does not matter that childhood is the process of learning how to be an adult, and that becoming an adult is a process of progressively mastering greater and greater freedoms -- the most important thing is that we are never seen to expose children to even the most minute level of risk. I really want us to have a real conversation about acceptable risk, informed consent, and human progress. We need it badly to regain our souls.