Imagine what it would be like if roads were made out of metal - solid metal mind you - instead of concrete and tar-seal. Indeed it would be possible to have metal roads instead of concrete ones, though there would be several disadvantages, and unless I'm very much mistaken, there would be no advantages. One disadvantage is that the roads would be sharper, since metal has a sharper texture than concrete does. Another disadvantage is that the roads would be more slippery, especially when it rains since metal has a more slippery texture than concrete does.
Cars would be much more prone to skidding, and pedestrians would be more likely to fall over and hurt themselves, and since metal has a sharper texture than concrete, people would be more likely to graze or cut themselves. Another disadvantage is that metal is more sensitive to heat, and the roads would be prone to heating up and catching fires on hot days. Roads would be more expensive to build and the construction just wouldn't pay off.
They'd have to start making special tires for cars so that they can withstand the texture of the metal roads since the tires would otherwise be prone to popping sooner or later after wearing out against the metal roads. Yet another disadvantage is that when it comes to doing road works, they'd have to use different machinery. I mean, whoever heard of a digger trying to dig up metal? So those are at least some of the disadvantages that cars and people would face if the roads were made out of metal instead of concrete.