I thought the answer to Dan’s question was purdy darn thorough. Thanks Cecil. I do have a question. I seem to remember several years ago that I read about how they were using recycled tires and shredding the rubber and using it in the mix for asphalt. However, I have never heard any follow up as to how that worked out in terms of road longevity.
Also, with my in-laws living in Florida, I have made many trips to Florida over the years and they live in the panhandle area, north of Interstate 10. Their asphalt road have lasted a good 20 years and I have always wondered if the sand/clay base underneath had something to do with their long-lasting asphalt roads?
Welcome to the Straight Dope Message Boards, ArrowDynamic, glad to have you with us, and you may be the first new poster of 2011.
When you start a thread, it’s helpful to other readers if you provide a link to the column in question. Yes, it’s the current one and on the front page this week, but it will soon sink into the depths of the Archives. So, providing the link helps others by eliminating searching time, and helps keep us all on the same page. No biggie, I’ve added it for you, and you’ll know for next time. And, as I say, welcome!
BTW, it took me several minutes to get Slug’s illustration. I mean, I saw what it was right away, but I dind’t put the concept together immediately: big ass truck
I agree that Cecil answered Dan’s question pretty thoroughly, except the part about workers getting paid triple. What I want to know is, how do I get a job there?
Peace,
mangeorge
Also, my understanding is that they pave runways for airplanes with hugely thick concrete- how long do those last? Could you build a 100 year highway if you just made it sturdy enough the first time?
Military runways are generally concrete (because the jet afterburners melt asphalt), but most civilian runways are asphalt. It is, however engineered and inspected to a much higher quality level than roads are generally done to. When I worked as a construction inspector, my specialty was paving, so I worked on pretty much everything from parking lots to military runways. Civilian airports are generally expected to last 30 to 40 years. Military runways may be better engineered, but they get harder use, so generally only last about the same amount of time.
Former construction inspector, here. It sucked. It was very difficult to get the asphalt, aggregate, and shredded tires properly mixed, then it was a problem getting the resulting mixture properly compacted. The result was that the road would be poorer quality, so that even if the rubber would theoretically improve the durability, the poorer quality job would result in much poorer durability. In NY state, at any rate, it was only done for about a year, when I was doing the job, before everyone gave up due to the constant cost and time overruns, and potholes appearing in less than a year.
I know something about this, I guess. Improvements have been made since Cheshire Human worked in the field; the stuff is actually pretty good - but of course, ain’t nothin’ absolutely perfect. To answer the Q, “asphalt rubber hot mix” seems to do a good job of extending the life of pavement, but: A) it hasn’t been around long enough to produce any indisputable solid numbers - and anyhow, ‘life of pavement’ isn’t a solid number to begin with. Okay, let’s just say it probably extends the life of pavement at least 5 years. B) There are different formulations around, some of which didn’t work out so well. C) There are different application methods around, and engineers are still learning which ones work best under which exact circumstances. D) It is some more expensive, but how much can fluxuate depending on many economic variables. E) It’s a little more tricky to put down; needs to be kept the right temperature. F) It’s got benefits beyond get-rid-of-used-tires and make-pavement-last-longer: it actually rides quieter, and it doesn’t fade out in the sun as fast, so it just plain looks better longer.
We plan to keep using it in Southern California. When circumstances warrant. Which they will, mostly.
Good point. That was back in the early 90s (give or take, I don’t remember an exact year), so if some group of people are really interested in making it work, further experimentation would have been done. Although I’m not in the industry, anymore, I still know people who are, and I haven’t heard of anymore work being done with it in this area, so I don’t know where it is being done. Still, it stands to reason that the “true believers” (not intended as derogatory) would keep trying, and maybe succeeding.
The California DOT is still trying it for the dense grade mix, although we’ve found that it is horrible in the open grade layer. It comes apart too quickly.
When the first toll motorway [freeway] was opened here in the UK back in 2002 the engineers wanted to ensure the road would last for longer than usual (as it was being developed as a commercial enterprise)
In order to increase the absorbency and overall longevity of the surface they mixed in 2.5m pulped copies of Mills & Boon romance novels, which has to be the most appropriate use I’ve heard for those books!
Wallenstein, we’d call that kind of a road here a “thruway” or “highway” or “toll road.” “Freeway” means the road is free to drive on, as opposed to roads where you pay tolls.
I’ve heard that it was coined to describe the federal highways built in California which didn’t feature tolls as those in the East do, but I don’t know if that’s correct.
As far as I know, “divided highway” is the nearest American equivalent to British “motorway”. A “thruway” or a “highway” can mean something much less – and you’ve forgotten “parkway”, “tollway”, “trafficway”, “expressway”, and probably others.
Here’s a BBC news reporton it - they used 45,000 books per mile of motorway.
As we only have a single pay motorway we’ve not really needed a separate phrase, so “motorway” covers the same type of road whether it’s urban, rural or cross-country, so it probably equates to a few road categories in the USA.
[mild hijack] I seem to recall that “highway” is a term of art in common law meaning any street to which the public has access, quite apart from its normal or planning use meaning a large or interurban road.
I have heard the term “freeway” (mis?)used to mean highways with no traffic stops- all access on or off is by ramps and all cross-traffic goes over or under each other.
Please, do not give trucks such a bad rap. They are totally essential to today’s economy. Without them there would no groceries in the store nor computers to write columns that trash trucks.
