"Chad Irby" wrote in message
...
In article ,
"Kevin Brooks" wrote:

"Chad Irby" wrote in message

Like I said befo bombers and heavy transport planes are
certainly a no-go (from sheer width), but fighters wouldn't
overload most Interstates by any stretch. A 50,000 pound plane on
a couple of tires is a lot of load, but compared to a
minute-by-minute pounding from 60,000+ pound semis, not so much.
You only need *really* thick concrete with thick supporting beds
when you plan on building something to take heavy loads and abuse
for a long time with little maintenance.

Eh? Care to imagine what the impact load of that 50K pound plane is
when it *lands*?

Quite high, but it's not like we're talking about doing this sort of
thing long-term. Landing a 50,000 pound fighter on a highway a couple
of times is *not* going to destroy the road. Highways are overdesigned
to take the load of thousands of trucks over several years.

Landing a plane on a concrete surface isn't as big a deal as you'd
suggest, either, since it's putting a *compression* load on the surface,
which is exactly what you want with concrete.

OK, I can see this is about as wasteful an effort as trying to convince you
that your punch-a-hole-in-Three Gorges thoughts were a farse. Your civil
engineering knowledge far outweighs mine, obviously, as you have developed
assumptions and design criteria otherwise unknown, not to mention the
presence of those strange rural "extra wide" interstate sections that you
can't seem to identify specifically, etc.


One other little thing: a lot of the more remote Interstates were
built with thicker concrete because it lasts longer - by adding a
couple of inches of thickness, you can *quadruple* the life of the
road (rule of thumb: for every extra inch of thickness, you double
the road surface life).

Huh? Never heard such a thing in my life as a civil engineer.

You know, I'm not surprised. Do the math sometime and get back to us.

I found that doing the math the last time I argued with you over something
you obviously had no grasp of was a wasted effort, so why bother? You make
these unsupported claims and then expect others to provide concrete
(heh-heh) disprovals, while ignoring the provision of
actual-honest-to-goodness civil engineering basics.


All of the pavment thickness in the world was not going to matter is
the subgrade was poor, or the base course was crummy or of
insufficient thickness.

Here's where your argument falls apart.

Not all of the road locations in the world *have* bad subgrade to begin
with. Lots of them are on hard ground, and are basically just waiting
for someone to overcoat them with a layer of reinforced concrete to be
really, really good roads - or runways.

Oh, goody! A new engineering description! "When a road is to be built upon
"hard ground", the pavment design will not have to consider the subgrade
condition or pay any attention to base course design--see Chad for
evidence." Is that the way it appears in the various design specification
requirements. Do you know what soil plasticity index refers to? Anything
about "liquifaction"? Shrink/swell? Caliche and what may be under it? You
obviously don't, so why am I even bothering asking?


And I don't recall any efforts to "overbuild" the interstate highway
system--the general procedure was to build to design requirments. And
as to adding to the lifetime with extra thickness...seems a bit
screwy given that the usual procedure was to lay by panels, with the
eventual uneven settling of those panels being the usual cause for
later resurfacing.

There you go again with that "usual" silliness. "Usual" isn't what
we're talking about here, no matter how many times you repeat it.

We are talking about a timeperiod here where the use of such roads would
have been even considered, and that means you better be going back deep into
the dark days of the Cold War, *before* the routine use of continuous pour
construction.


All it takes is someone saying "hey, we have a nice stretch of flat
ground with good characteristics, all we need is a bit of extra concrete
and you could land a frigging PLANE on it." Repeat that a couple of
dozen times over the tens of THOUSANDS of miles of Interstate, and there
ya go.

It is obvious now that there is a reason you have never been employed as a
civil engineer or highway construction supervisor, or for that matter in the
runway construction design business--and that is because you are so uteerly
clueless.


If anything, I'd bet that there wasn't a design requirement ahead of
time. Someone just noticed that they had a lot of potential improvised
runways, and went with it. It certainly wouldn't be the first time
someone in the government decided to allow for potential military use of
civilian resources (especially since the Interstates were defense roads
to begin with).

Having worked directly in the business of designing and building roads and
airfields, to include the truly short duration use "theater of operations"
strips and roadways, it is obvious that you again are shooting wildly from
the hip with the above. You might see Bufdrvr's comments as to why this is
not a likely scenario if you won't take my own comments--his notice of the
fact that a stip of pavment does not an airfield make is viable, even for
tactical fighters (you would be wise to read up a bit on the European
practices when it came to developing roadway dispersal strips--they indeed
tpically included *really* wide pavement sections, apron areas, and a taxi
system). The Pentagon is not in the practice of saying, "Hey, we have no
eartly idea if this would really work, but let's plan on it anyway".


But what about the subgrade prep and base course design
requirments??! They are equally as important as the pavment section.

But if you're not planning on using the road for a runway for years and
years, with no long-term damage, it's not as critical as you pretend it
to be. If you're building a thick concrete highway in the middle of
nowhere, the design requirements are *very* similar to medium runway
design. Good bed, a foot or so of concrete, linear and horizontal
reinforcement. It's not something you need for city streets, but if you
look at the cross-sections of runways and heavy-duty highways, you're
not going to see any show-stoppers for short-term use.

You again point to the fact that you are clueless when it comes to pavement
design with the above nonsense.

Brooks


Note that the runway at Palmdale airport has been operating for
*years*, and is only 14 inches thick...

Obviously with one heck of a good subgrade and base.

Gravel, on a clay and sand dry lake bed. Compared to "modern" runways,
not as high tech as you'd pretend. If you have a good solid piece of
ground to start with, you don't need to lay down six feet of work before
doing anything useful. And you only need two or three feet of concrete
over a good foundation if you're planning on landing B-52s or C-5s there
on a regular basis.

I've seen the runways under construction at Orlando International
Airport. They have a *thick* (upwards of six feet) base, with two feet
of concrete, but that's because they're building on a *swamp*. A lot of
places out West are basically rock or hard dirt, with no real variation.
Lock the water out with a layer of clay and a foot of concrete, and the
only wear and tear is going to be whatever you run over them.

--
cirby at cfl.rr.com

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Slam on brakes accordingly.