The joy of not having any infrastructure buried under the streets:
"Investigations at Pompeii have shown that particularly high volumes of traffic concentrated in narrow streets could wear down even a stone-paved surface in only a few decades,"
Probably more than you expect— here in Los Angeles (not a particularly old city), there's hundreds of asphalt streets that haven't been repaved since the 1930s and 1940s while they've been trapped in a Kafkaesque bureaucratic hell (the city disowned the streets for liability purposes). There's even a short stone street in Pasadena that dates back to 1900 or so. I don't think it's been entirely redone at any point, although you can tell where some of the granite chunks have been replaced.
Don’t forget all the concrete streets in LA! All the streets before a certain vintage were paved with concrete and are mostly intact where they haven’t been covered with asphalt.
Snarky answer: there are plenty around me, and they show it.
Serious answer: the street I grew up on, and most of the rest of the streets in that neighborhood, are 30 years old. They were last paved when I was nine. The ones that are newer were only paved because they were ripped up for utility work. There are plenty of roads in the US much older than a decade.
I'm not sure the road was already there when I was born, no recollection it was ever re-paved until they started to dig for utilities twenty-something years later, with all the trucks that carried stuff to build the beach neighbourhoods.
The difference between the old stuff and the new crap they use to pave it is unbelievable. Two years without repaving and it's full of holes.
Also, molten iron would have presumably been expensive back then - too expensive to simply pave a large part of the street with.
I don't really see evidence this was street repair as much as "occasionally on the roughest roads some drips of molten iron fell off the back of carts while being transported"
They show a whole segment of street repaired this way.
But, as noted in the article, they didn't just fill holes with iron. They filled them with loose aggregate, and glued it all together and to the road by pouring iron over it.
Transporting molten iron by road (for some reason other than fixing the road) would have been even more silly then than it is now. How many molten-iron trucks have you encountered?
There are "torpedo cars", that transport around 200 tons of molten pig iron by rail. Some are insulated enough to transport iron for over 24 hours. The energy advantage is massive.
I'm pretty sure no one moves large amounts of molten iron today. With ancient technology it would have been impractical even if they wanted to, maybe impossible.
They do it all the time, out of the furnace comes crude iron, which then must be moved to the steelmaking plant. It is cast into bars only at the steel plant. The carbon dissolved in crude iron lowers the melting point substantially, it's around 1200 °C, so you can actually transport it in steel vessels.
> occasionally on the roughest roads some drips of molten iron fell off the back of carts while being transported
I agree.
When I studied ancient history (and Pompeii) in school we were taught that the 'ruts' were a feature of Roman roads, not a bug. Carts were specifically designed to have axle width match these ruts, and were consistent throughout the Empire [0]. I think this is a low quality article that misconstrues a research paper as actual fact.
I am going to Pompeii in September so I'll try and have a look at these iron patches anyway.
"Investigations at Pompeii have shown that particularly high volumes of traffic concentrated in narrow streets could wear down even a stone-paved surface in only a few decades,"