Depends how either is implemented. I had to go to a town in east-central PA last weekend. Took the train. Outside of cities (per my phone’s GPS), the train was doing 110-120 mph, with not many stops. This wasn’t a “high speed train” — those were late 70s era rail cars being used between NYC and Pittsburgh.

No way a car (automated or not) being driven in a safe manner would beat that speed. Plus there’s something to be said for shared facilities, bathroom and bar car. Hard to do either in motion unless you’re in an RV.

Also, assuming CO2 is a concern, EVs are distance/charge-time limited, even more so in very hot or cold weather. Electric trains are basically unlimited-range EVs. Combining them with ZipCar type (autonomous) vehicles at the stations would yield an interesting transportation network.

And who says the trains themselves won’t be more heavily automated? If they don’t need a driver, it would be cheaper to run one or two car rail vehicles, 5x more frequently than we run five or ten car trains today.

[quote=AN]If every car is autonomous, I’m sure it would be safe for every car to be traveling at >100MPH, since they all will know where other cars around them are and where they’re going, so there would never be any surprise.[/quote]

It might be safe but it wouldn’t be efficient. Cars traveling at 100+ mph use up a a lot more fuel/energy than a car traveling at 55 to 65 mphs. Autonomous cars should be able to draft better though.

As for high speed rail. I like the idea of it but I don’t know that the cost of California’s project is worth it. Last I heard the project was going to be over $100 billion. That just doesn’t seem to be worth it.

[quote=spdrun]Autonomous cars will be unlikely to draft. The “cars following a foot from each other” thing is a myth. Any autonomous car would have to be as safe as possible for the manufacturer to avoid lawsuits. Even if you remove reaction time, braking distances vary significantly between vehicles, even vehicles of the same type (depending on load, tires, etc). Following distances might be slightly reduced, but not enough to draft.[/quote]

They are already testing platooning/drafting autonomous trucks in Europe. Maybe not drafting to the degree that is optimally efficient but enough to get some fuel/power saving efficiency.

http://bgr.com/2016/04/07/self-driving-trucks-platooning/

[quote=livinincali][quote=AN]If every car is autonomous, I’m sure it would be safe for every car to be traveling at >100MPH, since they all will know where other cars around them are and where they’re going, so there would never be any surprise.[/quote]

It might be safe but it wouldn’t be efficient. Cars traveling at 100+ mph use up a a lot more fuel/energy than a car traveling at 55 to 65 mphs. Autonomous cars should be able to draft better though.

As for high speed rail. I like the idea of it but I don’t know that the cost of California’s project is worth it. Last I heard the project was going to be over $100 billion. That just doesn’t seem to be worth it.[/quote]
What make you think it won’t be efficient? Keep in mind the current power output and gearing is specifically designed for good performance response @<80MPH. However, if everything is fully autonomous, then there's no need to worry about throttle response. Then the gearing can be much taller and engine tuning can gear toward higher low end torque. Which would greatly increase efficiency at the detriment of throttle response.

[quote=spdrun]Cars with 6, 7 speed transmissions or CVTs already have a tall top gear at detriment to throttle response. The issue isn’t gearing at this point — efficiency is limited by air, drivetrain, and road drag.

You might be able to gain efficiency by making cars lighter (lesser crash safety if they crash less), but above 80 mph, drag is mostly from air resistance. Frontal area isn’t going to change much unless you start building 4-person autonomous motorbikes.

And if anything, autonomous cars will be even more bloated since people will want to stand up, eat, go to the toilet. Think of an 80s VW Microbus except scaled up 25% in all directions for fatties.[/quote]
Average cars today still have drag co-efficient between .25-.35. They can totally reduce that to the high teens low 20s. Think Model 3. Regarding drive train, it’s not about the amount of gear but about the gear ratio of the overdrive gear. Then there’s the tuning of the engine. Think gas throttle response vs diesel gas mileage. If we no longer care about throttle response, then we can come up with engines like the turbo diesel that get awesome highway gas mileage at the detriment of throttle response.

Also keep in mind we’re talking about varying degrees of efficiency, not absolute in-efficiency. I would take slightly less efficiency for the convenience of autonomous car over train any day of the week and on Sunday.

The current HSR plan is incredible stupid, expensive, and already over budget & behind schedule.
The train between SF and LA is a 50 year project. At the moment they should focus on buying the right of way and doing the EIS for the the entire line. The focus should be on the following regional HSR.
1. LA-LV
2. LA-SD
3. LA-Bakersfield 3a. SF-Oakland-Sacramento
As population expands and the rail is actually used, then the line can be extended to other cities.

At the current cost, it is already the world’s most expensive rail program on a per mile basis, by a wide margin. It will likely be unsustainable and certainly won’t make a profit (maybe not even on a operating basis – not paying back debt).

But this project is about political power even if the money would be better spent on regional rail, like a major rail system out of LAX.