What would that do to the suspensions of ordinary vehicles? Concrete has joints, and around here they tend to be unforgivingly bumpy.

Isn't the resulting invention called a "train"?

Did the study consider the tyres? Surely this would be a simpler way to reduce the rolling resistance?

Ok a mile of road costs about 1-3 million dollars to build.
Adding 10% Carbon Nanotubes by weight - seriously? I love researchers who come up with practical and usable suggestions!
So let's see, a gram of carbon nanotubes costs USD 100. So their suggestion would change the cost of 1mile road to go from millions to billions!! Awesome let's do that so we can increase the fuel efficieny of a truck by 10%. Also the cost to fix harder roads are exponentially higher.

Sure why don't we just also make it mandatory for the trucks to have steel wheels which being much harder than typical truck tires won't have all that nasty friction to deal with. Of course, slip n slide on water and ice might be a problems and the road damage per mile would be astounding. Nice try but not gonna happen in America it's too cheap. America won't build it's Interstates like Germany's Autobahns.

Is this not a reason why freeways are concrete ?- Much stiffer than an asphalt over compacted roadbase - as per regional roads.

"if 10 percent of US road surfaces were annually made stiffer over the next 50 years", the carbon footprint of the massive reconstruction work would far surpass any incremental savings, not to even mention the exorbitant financial outlay. Stiffening a road takes much more than just stripping the existing asphalt and repaving, and that's costly enough already. But to make a road stiffer, you need to replace the layers under the asphalt---practically rebuild the road. And BTW the math is wrong: 10 percent annually over 50 years is 500% altogether. I don't suppose the authors are proposing stripping and rebuilding all the roads in the US five times over, so I assumed the word "annually" is an error---the concept is preposterous enough even without it.

What a great, futuristic idea. We could even make dedicated roads for freight out of steel, and the rolling efficiency would be so great that we could string multiple containers together in long chains, pulled by a single engine!

Hard truckin' truth, thanks. Forgot what it felt like to move a rig. Gonna be amazed if only 10% carbon fiber or graphene can stiffen up a road; concrete bases make a good start though. Good decarbonizing stuff and no lost rubber to the Miata or Aston Martin.

I thought that as concrete cures it emits a large amount of CO2 - thus the reason construction is cited as major contributor to greenhouse gasses - from the WIkipedia entry called "Environment impact of concrete":
"The cement industry is one of the main producers of carbon dioxide"
Was this included in the calculus of saving emissions?