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That's true but you can make some assumptions that greatly reduce the edge cases if you apply some basic rules. e.g. I can imagine self driving only lanes with

That's true but you can make some assumptions that greatly reduce the edge cases if you apply some basic rules. e.g. I can imagine self driving only lanes with high barriers on either side, at which 200+ mph speeds are achievable.

sqeaky 9y ago
I agree high speeds would be achievable but some fundamental aerodynamics must be solved to achieve that. Cars can catch a bit of and gain lift they are often airfoil shaped. Its not impossible, but the goals of an F1 car are directly at odds with a consumer sedan.
lorenzhs 9y ago
This "200+ mph self-driving cars" thing gets repeated a lot on HN but I've never seen anything to suggest that it would be remotely fuel-efficient. There is a reason why today's high-speed rail rarely exceeds 200mph / 320km/h, namely that around that value, wind resistance starts to exhibit cubic growth. Even with ultra-dense automated slipstream driving, I can't imagine this being very efficient. Some citations would be greatly appreciated. Tyres might be an even bigger problem. See the Bugatti Veyron: "It uses special Michelin PAX run-flat tyres, designed specifically to accommodate the Veyron's top speed [258mph / 415 km/h], and cost US$25,000 per set. The tyres can be mounted on the wheels only in France, a service which costs US$70,000" from https://en.wikipedia.org/wiki/Bugatti_Veyron https://en.wikipedia.org/wiki/Bugatti_Veyron
dpark 9y ago
So your vision of self driving cars involves dedicated roads being built for 200mph speed? So essentially you think the best use case for self driving cars is to replace rail between cities? Who do you imagine will vote for the many billions of dollars it would cost to build these self-driving Veyron tracks for the absurdly wealthy? The people who can afford 200+ mph cars can probably afford to employ drivers anyway.
- albertgoeswoof 9y ago
  It's part of the self driving vision. Veyron's could be as cheap as other high-end cars if mass produced. The point of self driving is not really about replacing drivers but making overall transportation more efficient. The advantage of lanes over trains is that a) it would be an order of magnitude cheaper to convert a car lane into a self driving lane than build an entire railway line b) self driving cars can still go on normal roads at lower speeds, so you solve the last mile problem
  - dpark 9y ago
    > Veyron's could be as cheap as other high-end cars if mass produced. Yeah, right. Lack of scale is definitely why the Veyron was so costly. It definitely isn't the difficult engineering with a W12 engine or the $75k tires to keep it from killing the passengers in the event of a flat. Also, most people don't drive "high end cars". I hope self driving eventually isn't something restricted to the wealthy. > The point of self driving is not really about replacing drivers but making overall transportation more efficient. Long haul between cities is not where cars are inefficient. Cars are inefficient in traffic. > it would be an order of magnitude cheaper to convert a car lane into a self driving lane than build an entire railway line Not really. You're stealing lanes from cars that can't self drive or can't drive 200mph, so you're making everything worse for everyone else if you do this. You also need to build on ramps and off ramps everywhere because your 200mph lane cannot safely use the same exits as the 70mph lane next to you. > self driving cars can still go on normal roads at lower speeds, so you solve the last mile problem The last mile is the real problem, though. Traveling between cities rapidly is not a real problem except for shipping.
- lorenzhs 9y ago
  Switzerland has a few car shuttle trains ("Autoverlad") to avoid mountain passes: https://en.wikipedia.org/wiki/Car_shuttle_train#Switzerland https://en.wikipedia.org/wiki/Car_shuttle_train#Switzerland - no advance booking required. The Eurotunnel shuttle between France and the UK is another great example (but has inflexible bookings). High-speed car shuttle trains might be the better solution, if you insist on using cars.

sqeaky 9y ago

I agree high speeds would be achievable but some fundamental aerodynamics must be solved to achieve that. Cars can catch a bit of and gain lift they are often airfoil shaped. Its not impossible, but the goals of an F1 car are directly at odds with a consumer sedan.

lorenzhs 9y ago

This "200+ mph self-driving cars" thing gets repeated a lot on HN but I've never seen anything to suggest that it would be remotely fuel-efficient. There is a reason why today's high-speed rail rarely exceeds 200mph / 320km/h, namely that around that value, wind resistance starts to exhibit cubic growth. Even with ultra-dense automated slipstream driving, I can't imagine this being very efficient. Some citations would be greatly appreciated. Tyres might be an even bigger problem. See the Bugatti Veyron: "It uses special Michelin PAX run-flat tyres, designed specifically to accommodate the Veyron's top speed [258mph / 415 km/h], and cost US$25,000 per set. The tyres can be mounted on the wheels only in France, a service which costs US$70,000" from https://en.wikipedia.org/wiki/Bugatti_Veyron https://en.wikipedia.org/wiki/Bugatti_Veyron

dpark 9y ago

So your vision of self driving cars involves dedicated roads being built for 200mph speed? So essentially you think the best use case for self driving cars is to replace rail between cities? Who do you imagine will vote for the many billions of dollars it would cost to build these self-driving Veyron tracks for the absurdly wealthy? The people who can afford 200+ mph cars can probably afford to employ drivers anyway.

albertgoeswoof 9y ago
It's part of the self driving vision. Veyron's could be as cheap as other high-end cars if mass produced. The point of self driving is not really about replacing drivers but making overall transportation more efficient. The advantage of lanes over trains is that a) it would be an order of magnitude cheaper to convert a car lane into a self driving lane than build an entire railway line b) self driving cars can still go on normal roads at lower speeds, so you solve the last mile problem
- dpark 9y ago
  > Veyron's could be as cheap as other high-end cars if mass produced. Yeah, right. Lack of scale is definitely why the Veyron was so costly. It definitely isn't the difficult engineering with a W12 engine or the $75k tires to keep it from killing the passengers in the event of a flat. Also, most people don't drive "high end cars". I hope self driving eventually isn't something restricted to the wealthy. > The point of self driving is not really about replacing drivers but making overall transportation more efficient. Long haul between cities is not where cars are inefficient. Cars are inefficient in traffic. > it would be an order of magnitude cheaper to convert a car lane into a self driving lane than build an entire railway line Not really. You're stealing lanes from cars that can't self drive or can't drive 200mph, so you're making everything worse for everyone else if you do this. You also need to build on ramps and off ramps everywhere because your 200mph lane cannot safely use the same exits as the 70mph lane next to you. > self driving cars can still go on normal roads at lower speeds, so you solve the last mile problem The last mile is the real problem, though. Traveling between cities rapidly is not a real problem except for shipping.
lorenzhs 9y ago
Switzerland has a few car shuttle trains ("Autoverlad") to avoid mountain passes: https://en.wikipedia.org/wiki/Car_shuttle_train#Switzerland https://en.wikipedia.org/wiki/Car_shuttle_train#Switzerland - no advance booking required. The Eurotunnel shuttle between France and the UK is another great example (but has inflexible bookings). High-speed car shuttle trains might be the better solution, if you insist on using cars.