Metal roads. But since metal is expensive you probably want just two strips of it under the wheels. And since it will wear away at the rubber you probably would want the cars to have metal wheels as well. And at that point you could make the wheels form around the rails in order to make it easier to move fast without sliding. And then you could make the cars a lot bigger and link them together and have one big car push a whole bunch of them.

asphalt is cheap (and flashy) part of road construction, the really important, expensive, non-flashy and prone to corner cutting part is building solid, thick, high-quality layer of aggregate underneath. if you don’t have that, no matter how many layers of asphalt you slap on top it will break every winter

this is an instance of https://en.wikipedia.org/wiki/XY_problem

If you want to do some reading, google the Minnesota Department of Transportation - MnDOT - is known nationally and internationally for it’s testing of materials and construction of roads over a long term. There are some test sections dating back to 1973 that are still being monitored and studied. What make MnDOT studies valuable to other states, (and even other countries), is the wide temperature swings in the state. Temperatures can swing from -40F to over 100F in the course of one year.

A simplistic view - What damages road surfaces that happen over the winter and spring is the tiny cracks that are cause by the thermal expansion and contraction of the road surface that traps moisture which then repeatedly freezes and thaws. Freezing water expands creating a bit larger crack which traps more moisture - wash rinse and repeat over time and the surface flakes away causing potholes and broken roads. Add in the flexing of the road with heavy traffic, and roads will tend to break up and become rough. But there a a bunch of other considerations from subsurface prep to the general geology of where you want to build your road that all add to the life expectancy of the road itself.

Very generally, for heavy high speed traffic all weather roads, concrete roads seem to be gaining favor as the mixes get better additives.

Asphalt is pretty amazing given the amount of wear it goes through. It’s basically infinitely recyclable, very flexible, goes down fast, and is relatively easy to work with.

Specifically talking about asphalt vs. concrete:

• Asphalt is relatively cheap vs. concrete. This is partly because asphalt is a whole lot easier to recycle than concrete, which is almost un-recyclable, but also because asphalt is a relatively “simple” material - it’s mostly petroleum byproducts and gravel.

• Concrete doesn’t grip very well, compared to the relatively textured surface of asphalt. Especially when wet! This is why you often see concrete formed with “ridges” or “bumps” cast into it. However…

• This also makes concrete noisier and bumpier to drive over, making drivers less happy. It’s why it’s often used for short, low-speed uses like driveways, parking lots, or side streets.

Just about the only thing concrete has going for it is it’s endurance, which it definitely wins handily.

Every few years another engineered road solution is conceived - I’ve seen variations that would use glass which could be ‘re-fused’, concepts for recycling plastic waste, and many more. Most of these run into the issue that they’re either less ‘grippy’, or that they simply cost more even accounting for the longer lifespan.

There is no known viable replacement for asphalt. They all either lack certain features to make it viable in all conditions, or they are exponentially more expensive to produce in big quantities.

There are various green concrete versions, but none that caught up yet. I know the latest trend is mixing graphite into concrete as it has a lot of benefits, but I’m not sure how cost viable it is at scale.

Asphalt with recycled plastic waste mixed in reportedly holds up stronger. But people are freaked out about microplastics so it probably won’t happen. The irony is that the majority of road microplastics actually come from tires.