You are so right, I think it doesn't even have to be electrified. With self driving tech soon emerging, probably it's a matter of time until lanes on the highway designated for self piloted cars will appear. There they can drive at higher speed and closer to the car in front, meaning higher capacity on the same highway. And you still have personal freedom, just get off the highway and go where you need to, when you need to.
The same with trucks. Designated lane for self driving trucks can be safer. Can you imagine a truck being able to go 16 hours straight, with the truck driving itself while the driver sleeps? Double road capacity right there with completely existing infrastructure and completely existing costs.
All this without having to build expensive new infrastructure for something that nobody really wants.
By the time self-driving tech becomes good enough, this project will be completely pointless and used for filming a Speed reboot.