Car Train/Platooning update

We’ve discussed this before but just a quick update on progress made

Trouble is, Sartre makes no provision for leaving the convoy.

The OP’s link says otherwise:

Huh, I was under the impression there was no exit procedure.

I just don’t understand why they are starting out with passenger vehicles. It seems to me that the natural first roll-out is for commercial long-haul trucking with drivers alternating in the lead.

Probably because the current limit on the length of a road train is legal, not technical. There’s not much point letting two trucks with two trailers each operate as a single vehicle if one truck with four trailers could do it just as well.

what’s in it for the driver of the lead vehicle? Eg why should they volunteer to be responsible for driving the 6-8 cars behind them?
And how does someone in the middle leave if it’s not a dual lane motorway?

Also considering the conduct of “professional drivers” here in Australia and the hours and fatigure they are exposed to the last thing I’d want to do is put my life in their hands.

There is no exit procedure: human must make their own exit procedure under Sartre :slight_smile:

Beaten to it. I was going to say if he was confusing exit with existentialism.

As for the car device, it is provably a solution that will have to compete with the coming autonomous vehicles, not sure if the fuel efficiency then will be enough to convince people to give control to other drivers even just temporarily.

I figured Xema would realize the whoosh sooner or later and I was just waiting for the d’oh!

Jokes aside, with the aging population I figure we’ll have more and more cases of old people causing fatal accidents and it’ll be the insurance companies refusing to cover them at any price that’ll be the impetus for automated cars or some hybrid solution as described in the OP’s link.

Can you point me to something about those legal limits?

The concept is a higher tech convoy, much how many truckers do it now but able to stay a bit closer to each other and to sleep or relax for prolonged shifts while the lead vehicle driver is fully alert driving for a shortish shift, yet still getiing off at their own destination points and proceeding more locally independently from there.

I’m going by Wikipedia, but it says that trucks in the U.S. are limited to two trailers with a maximum length of 63 feet. If the proponents of the car train focused on doing the same thing with trucks, there’s no guarantee that lawmakers wouldn’t simply treat the two+ trucks as a single vehicle if they’re all under the control of a single driver.

So … not only would the lead driver be responsible for his own passengers, but also for passengers in the 8 cars behind him? The insurance company would run screaming down the street.


  1. The initial roll-out is in Spain (with plans to roll-out over the EU), not the US.
  2. They are separate vehicles, each traveling under its own power, and each with its own driver inside. There is no guarantee that lawmakers wouldn’t treat them as trailers but none that they would either. I’d suspect that something like this would only happen in the US with Fed level involvement and likely initial subsidization for early adopters. The legal issues would of course be resolved before that.


Most analyses conclude that automated vehicle platooning would substantially increase safety. I suspect that insurance companies would end up providing discounts to those who participated in the program.

One time while hitchhiking, I got picked up by one of those huge trailer trucks carrying 20 brand new cars. I climbed up the side of the cab and opened the door. The guy said, “I don’t have much room up here, why don’t you get into one of the cars out back.” So I did. And he was really into picking people up because he picked up 19 more. We all had our own cars. Then he went 90 miles per hour and we all got speeding tickets.

-Stephen Wright

Doesn’t matter. The same sort of laws exist in Europe.

I disagree. Something made the lawmakers decide that long road trains needed to be prohibited, and I don’t think that platooning avoids that. And even if each has a “driver”, they aren’t actually controlling the vehicle. Only the front driver is.

Well then I again ask you to please direct me to what those laws are.

As to your other point … you have a conclusion about whether or not the reason for prohibiting multi-trailer trucks applies to platooning without knowing even what the reason for the law is? Just that there must be some reason and that it must also apply, even though platooning avoids having multi-trailer trucks getting on and off at ramps and through streets approaching and departing the highways and could form into smaller units as needed for various potential circumstances.

Well no arguing with that.

I would never join a road train that does not have a professional driver at the head. Even then. I donno. It’s different than an airplane. Presumably, any idiot driver could join and then ask to leave, and screw up the process or have their car fail or whatever. Not for me.

I think that a big problem with this idea is cars merging onto the highway. And passing the road train. Even in Kansas, it’s too long and might cause problems.

If I were an insurance company, I would be loath to cover a vehicle as part of a platoon, when I know nothing about the lead driver. I have information about the driver I’m insuring, and I’ve calculated his/her premium based upon that information. Insuring him/her within a platoon would be asking me to cover an unknown driver who has an unknown driving history (unknown to the company). I don’t think I’d do that.

enipla brings up good points. How would you be sure that the lead driver is qualified? That would concern me as a participant.

I found a little bit about the length limit:

From FHWA.

The U.S. Code seems to be based more on weight than length, although length figures into the formula:

Source: United States Code, Title 23 - Highways, Chapter 1—Federal-Aid Highways, Subchapter I—General Provisions.

Here’s something from Maine: