Come gather round kids and listen to granma Alcaran tell story.
A long time ago, around the 1920s, some people made the first asphalt roads. It was great stuff, could be endlessly recycled, was smooth yet grippy and just amazing for the modern cars that were becoming more popular.
So engineers figured they should build these things to last. They made roads that would, at the foundation, last hundreds of years. There are hundred year old roads today that will structally outlast your grandkids (not counting the massive potholes in the top few centimeters).
But then something happened. More people were born, new towns were started, and we got smarter too. We realized stuff needed to change. Wider roads, different curves and exits, other angles and wider spaces for safety, all sorts of things. And we ripped up roads that would last hundreds of years after only a few decades, to replace them with something better.
And every time someone says “why don’t we build to last”, the answer will be the same. We can’t predict the needs of the future. The romans could be sure that people would be walking the Via Aurelia for a thousand years. We’re not even sure we still want that overpass there by 2030.
Nice story, but no. The answer is cars. Trucks, too. A nice roman road would’ve been unusable after a few decades if they ran thousands of multi-ton vehicles over it every day. Road wear scales with the square of the weight, so a car that’s twice as heavy will have 4x the wear. 10x the weight, 100x the wear.
Since you don’t realize there are very different processes going on between surface damage and structural damage to the foundations, I’ll assume you’re just repeating the internet and don’t actually know anything about building roads.
The top layer isnt part of what is considered the structural component. It’s also extremely unfair to compare it to roman roads, because asphalt and natural stone have completely different properties and qualities. But more importantly, it doesn’t take engineering skill to build the top layer, every civilisation ever has built roads by just putting down stones, and those roads are all gone. The skill in building roads is in the foundational layers, they’re what makes your roads last.
And there are many modern roads in the world that are a meter of sand, a 50cm of aggregate, 30 to 50cm of sand asphalt and then a lower layer of 12 centimeters of underlayer asphalt followed by anything from 3.5 to 10 cm of surface layer depending on the type used. Those first few centimeters will of course need replacing every 5 to 10 years, but the road construction underneath is 80 years old and will easily last another 200 (the models will usually show “>100”)taking into account the wildest growth of traffic
But we stopped building like that, because we tend to not want roads to be in the same spot for 300 years. The romans did, because not only did their traffic needs not visibly change (can’t blame them for not having modern counting systems built into the road), they also had no concept of things like that. People would always need to travel from Rome to the outer cities. They would always need to walk to Gaul. That would never change in their worldview. So they obviously built to last forever.
We don’t. We have a very clear knowledge that we’re improving constantly and that we will probably change things around a few times before the end of the century.
Come gather round kids and listen to granma Alcaran tell story.
A long time ago, around the 1920s, some people made the first asphalt roads. It was great stuff, could be endlessly recycled, was smooth yet grippy and just amazing for the modern cars that were becoming more popular.
So engineers figured they should build these things to last. They made roads that would, at the foundation, last hundreds of years. There are hundred year old roads today that will structally outlast your grandkids (not counting the massive potholes in the top few centimeters).
But then something happened. More people were born, new towns were started, and we got smarter too. We realized stuff needed to change. Wider roads, different curves and exits, other angles and wider spaces for safety, all sorts of things. And we ripped up roads that would last hundreds of years after only a few decades, to replace them with something better.
And every time someone says “why don’t we build to last”, the answer will be the same. We can’t predict the needs of the future. The romans could be sure that people would be walking the Via Aurelia for a thousand years. We’re not even sure we still want that overpass there by 2030.
Nice story, but no. The answer is cars. Trucks, too. A nice roman road would’ve been unusable after a few decades if they ran thousands of multi-ton vehicles over it every day. Road wear scales with the square of the weight, so a car that’s twice as heavy will have 4x the wear. 10x the weight, 100x the wear.
Since you don’t realize there are very different processes going on between surface damage and structural damage to the foundations, I’ll assume you’re just repeating the internet and don’t actually know anything about building roads.
The top layer isnt part of what is considered the structural component. It’s also extremely unfair to compare it to roman roads, because asphalt and natural stone have completely different properties and qualities. But more importantly, it doesn’t take engineering skill to build the top layer, every civilisation ever has built roads by just putting down stones, and those roads are all gone. The skill in building roads is in the foundational layers, they’re what makes your roads last.
And there are many modern roads in the world that are a meter of sand, a 50cm of aggregate, 30 to 50cm of sand asphalt and then a lower layer of 12 centimeters of underlayer asphalt followed by anything from 3.5 to 10 cm of surface layer depending on the type used. Those first few centimeters will of course need replacing every 5 to 10 years, but the road construction underneath is 80 years old and will easily last another 200 (the models will usually show “>100”)taking into account the wildest growth of traffic
But we stopped building like that, because we tend to not want roads to be in the same spot for 300 years. The romans did, because not only did their traffic needs not visibly change (can’t blame them for not having modern counting systems built into the road), they also had no concept of things like that. People would always need to travel from Rome to the outer cities. They would always need to walk to Gaul. That would never change in their worldview. So they obviously built to last forever.
We don’t. We have a very clear knowledge that we’re improving constantly and that we will probably change things around a few times before the end of the century.
Weird, because I always hear it’s the 4th power.
https://en.wikipedia.org/wiki/Fourth_power_law
Might’ve been misremembering, I think you’re right :D