So, the Swiss want to repave a busy road. As you might expect, they go about it in a very Swiss way.
I’ve had to supervise the paving of a few short stretches of road, and lots of parking lots, so maybe I can tell you what’s going on in the video.
First, they’re scarifying the road. This is done by a big machine with lots of nasty teeth that can handle grinding away at little rocks suspended in emulsion all day. They’re removing what is called (in the US) the wearing layer of pavement. What’s underneath is sometimes referred to as scratch pavement here. I have no idea what the Swiss call theirs.
All the stuff they grind up will be recycled into more pavement. The grinding wheels on the machine are circular, so it leaves a bit of a curved ramp at the end of the run. A worker uses a handheld abrasive wheel to cut a slot at the same depth as the scratch pavement level, and then a guy with a jackhammer (pneumatic) cuts out the remainder to make a square place to butt the new pavement into the existing stuff.
Then a guy heats the edge of the old pavement with a propane torch, followed by a guy spraying emulsion. Asphalt emulsion is the goo that holds asphalt together, and acts as a kind of glue between old and new. Then they feed in a more substantial joint tape that’s also hit with a torch as it pays out.
Then they do something that’s sort of old-fashioned. They spray a heavy coat of emulsion over the whole surface, and then put what looks like recycled pavement over it. That serves as the sub-base, or scratch pavement. Roads used to be paved that way fairly often in the US. Just watch Cool Hand Luke to see it done by hand.
Then comes the actual pavement machine. It has wings that fold out to accept bituminous asphalt from a series of trucks, ferried by neat little front-end dumpers. That stuff (hot-mix asphalt) comes very hot indeed from the plant, between 300 and 400 degrees F. If you’ve ever seen a paving crew at work, you’ll often see them strap squares of plywood on their boots to keep the soles from melting when you walk on the fresh pavement. In the US, many dump trucks that carry pavement have heating elements in them to keep the temperatures up during delivery. Cold asphalt doesn’t spread or roll very well.
There’s some extra torch and shovel work at the join to the existing pavement. Then rollers roam over the hot pavement to compact and smooth the surface. A worker runs a gas-powered plate compactor over the edges to avoid having the rollers straddle the seam and risk breaking the existing edge.
And of course the most Swissiest thing about this very Swiss thing is that they built an articulating bridge on wheels that regular traffic can travel over unimpeded while the men work in safety underneath, and the bridge creeps down the roadway as the work is completed.
Sometimes, when I look out my car window, I don’t know where I live exactly, anymore. But it sure as hell ain’t Switzerland.
One Response
My husband’s Uncle Billy was head of the road crew in our rural area. One year some company sold him on a “new product” which Uncle Billy and the state approved using. He and his men spent about a week renewing the road in our isolated valley.
We all lived on various small ranches in those days so most of the population was family. After about three days the road begin rolling up and down into galleys. Narrow and frequent, but regularly timed gullies. That is to say each gulley and ridge was the exact distance from the one on either side of it. It was all very regular. Nobody knew what to say but “Geez Louise Billy WTH did you do this time?” He took an early retirement a year or so later.
P.S. He was a decent and kind man that trusted someone’s system.