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Comment by peteretep | Hacker News Reader

When you have a fully automated motorway, with vehicles able to drive safely at any speed, I wonder what the cost and physical limitations of driving very very fast while still on the ground are, vs potentially flying.

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Why would you have an automated motorway? Why not have rail instead and get a self driving cab from the terminal to your final destination. Self driving cars make more sense for short distances.

Railroads are better than self-driving cars for most purposes -- more efficient, safer, simpler to maintain, and _much_ less complicated to create -- but the US apparently doesn't have the political will to build new ones anymore. It reminds me of the failed attempt to upgrade the air-traffic control system back in the '80s and '90s...

you could reduce some aerodynamic drive by putting the cars end to end. essentially your car knows its destination and moves to the appropriate lane, the further you need to travel the more likely you end up in a far lane where cars are kept at a higher pace and closer together.

think of it as a modern version of Chicago highways where the left lanes get sectioned off on occasion with less chances to exit all to keep people in lanes consistently to reduce accidents from moving lane to lane.

fully autonomous cars and lanes dedicated to them and similar buses will remove the need for rail with in city limits beyond what exist. with no need to transfer vehicles and dedicated lanes you don't need as much planning for changes in travel patterns. fixed rail is always trapped, worse you end up with periods where you have too much capacity or too little and the inflexibility of track means no one else can use it. dedicate roadways can use the same space and be entirely flexible with easier maintenance and lower overall costs

In Toronto we have the collector/express system for the 401, it is still a mess: https://upload.wikimedia.org/wikipedia/commons/f/f9/Highway_...

At a certain scale congestion is inevitable, whether automated or not, faster traffic will eventually need to merge with slower traffic...

You get a lot more drag close to the ground. So, it depends on how 'fast' you mean by fast.

Still, I think in and near city PRT will have a much larger impact. If you could average 40mph in and near city's that's a huge difference in peoples lives.

Anything over ~80-90mph is going to be extremely inefficient due to drag coefficient.

Flew to Orlando from PA. Drive time would be 15 hours. Flight time is 2.25 hours. Left for airport at 7:30 am arrived home 8:45 pm (Traffic and just getting there 1.5 hours early and a non-direct flight)

I saved 3.5 hours, but cost me hundreds of dollars. I think self-driving cars will change the way we travel to things on land that are 16 hours of driving or less.

That's an interesting point, and also seems to fit in to the supersonic jet narrative: people aren't willing to pay a (sufficient) premium to shave a few hours off a flight. In the same way, you might be willing to accept a couple of extra hours travel time to be in the comfort of your own vehicle.

Yeah, I think this gets especially fascinating if people don't own their own vehicles. Uber, etc., are pretty big now, but they're still employing people with regular off-the-shelf cars. I think eventually we could reach a tipping point where most people don't own their own vehicles and Uber, etc., get so large that it makes sense for them to start building/buying purpose-built vehicles that could be dispatched according to your particular task. Commuting solo? You get a super-fuel-efficient one-seater. Driving 16 hours? You get a car with a bed in it, and your trip will take place overnight. Go to sleep in PA, wake up in Orlando. And so forth.

See, that's the thing. These days you need to hurry up to get the to airport hours before your flight, then wait. Etc...

I do this a lot flying to Ottawa. Leave at 6am, get home at 10:00pm. I'd consider driving if the car was autonomous.

It costs ~300$ to drive 1,000 miles. So, I don't think a few hundred is for a ticket is actually more expensive.

Not for gas, not in the US right now, unless maybe you plan to travel in an old truck or some horribly inefficient sportscar. If you're factoring in wear and tear on your car, maybe... But highway driving isn't particularly hard on most vehicles either.

The time invested is probably the most expensive part of driving, and that's where flying has been losing its lead for years.

There is a wide range of costs, but 30c/mile of highway driving is actually fairly cheap if you include everything.

PS: "57.5 cents per mile for business miles driven, up from 56 cents in 2014"

"The standard mileage rate for business is based on an annual study of the fixed and variable costs of operating an automobile, including depreciation, insurance, repairs, tires, maintenance, gas and oil."

Where I live I can travel in a electric car for roughly 1/6 of the cost of petrol. Of course the calculation is more complicated than that, cost of the vehicle, service etc. My guess is that this will be competitive with this type of air travel.

What about a couple or a family though?

But during most of that time you could read, work on a laptop, etc. Not so when driving.

Just the two hours of flight time actually. Otherwise you're driving, waiting in line, walking, getting luggage, etc

With sufficiently networked cars, you can reduce the following distance between cars and significantly reduce the drag coefficient.

(Obviously there are safety issues, but we're playing the 'cars are smart enough to make everything perfectly safe' game)

Assuming we have fully electric cars and "solved" the electricity production problem, I don't see the inefficiency of going fast at ground level as being a significant problem. That's a big "if" though.

The problem is that at motorway driving speeds, where air resistance is dominant, the power required is proportional to the cube of the velocity. Driving at 100 mph instead of 80 mph will halve your range.

Cube? I was almost sure it was square

underground evacuated chamber?

Electric cars locally, hyperloop for greater distances, aircraft running on biofuels as a last resort.

At 200+ mph it becomes hard to stay on the ground. :)

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