Thickness of Runways?
Philip Papadopoulos
How thick is the average concrete runway that is capable of handling
"heavies" (e.g. 747,767, MD-11, L1011, AB300, etc.)?
Thanks,
Phil
Michael Yip
--
I remember that thickness of the runway is one thing but the
major factor really depends on the "distribution of weight"
over the wheels of the aircraft.
I forgot where I read it but the distribution of weight on a
MD-80/DC-9 type of aircraft is not as even as, or not as "light"
as a 747. The 747 has more wheels to spread over its weight
while the MD-80/DC-9 has fewer to do the same.
===============================================================================
Michael E. Yip
Sybase, Inc., Internet_style: Micha...@sybase.com
Emeryville, California. UUCP: {sun,lll-tis,pyramid}!sybase!yip
===============================================================================
WOLPER_JAMES
>the major factor really depends on the "distribution of weight"
>over the wheels of the aircraft.
Runway weight bearing capacities vary with landing gear configuration:
single or multiple wheels, multiple trucks, etc. Publications
like the US Airport/Facilities Directory list these capabilities.
Here is some (possibly obsolete) data on Seattle-Tacoma Int'l runway 16L:
configuration max allowable weight (1000s of lbs)
single wheel type (eg, DC-3) 100
double wheel type (eg, DC-6) 200
dual-tandem type (eg, B-707) 350
double dual-tandem (eg, B-747) 825
Oddly enough, the Canada Flight Supplement does not list runway
weight bearing capabilities; this may be due to a Transport Canada
national standard (ie, data published elsewhere).
Jim Wolper Comm ASEL IA CFI
Department of Mathematics
Idaho State University
Pocatello, ID 83209-8085 USA
Scott Decker
more info when I can. In a reascent (about 2 weeks or so), I read that
some one was looking for info on the thickness of runways. I called the
local Airport Authority Engineering Dept. and asked the Sr. Engineer about
the runway thickness at the Reno Cannon Airport. I must admit that the
info is not enough to build a runway but then.... You get what you pay for :-)
He said that the engineering department does a study on the amount of
traffic and the type (size, type, number of landings, etc.) of aircraft
that will be using the runway. The report is sent to the FAA for review
and they determine the specs that must be used for the field. The runways
at Reno are 17" thick and are concrete. This seems to be a typical number
and can go to 20". Reno has had Air Force 1 land here and the Concord on a
promo trip for a local radio station. I'm not sure if I have answered the
question posed, but I hope it helps.
The info above is to my best memory, (not that great) and from a phone call
with the Sr.Engineer at the Airport. My Thanks go to him on this one.
Scott Decker
Jeff Berton
> How thick is the average concrete runway that is capable of handling
> "heavies" (e.g. 747,767, MD-11, L1011, AB300, etc.)?
The stress imparted to a runway is a function of, among others, strut load,
number of tires per strut, tire spacing, tire size, and even tire pressure.
Here are some numbers from Lockheed's "Landing Gear Design Handbook" (1982):
Aircraft Gross Weight Concrete Thickness at Static Load
Type (lbs) for Unlimited Operation (in)
747 775000 12.8
C-5 769000 10.0
L1011 410000 11.9
C-141 316000 12.3
707 297000 11.3
An interesting comparison involves the 747 vs the C-5. Both have similar gross
weights, but the unusual gear arrangement of the C-5 allows nearly 3 inches
less runway thickness. And the C-141, at four-tenths the weight of the 747,
requires nearly the same runway thickness.
--
Jeff Berton, Aeropropulsion Analysis Office, NASA Lewis Research Center
jef...@voodoo.lerc.nasa.gov
Terrell D. Drinkard
Michael Yip <y...@sybase.com> wrote:
>I remember that thickness of the runway is one thing but the
>major factor really depends on the "distribution of weight"
>over the wheels of the aircraft.
The thickness of the runway depends primarily on the subgrade condition and
the Aircraft Classification Number (ACN) of the planes the airport owners
expect to serve. The more swamplike the subgrade, the thicker the runway
needs to be to serve the same size airplane. ACN is a measure of weight
distribution. The corresponding measure for the pavement is the PCN, or
Pavement Classification Number. The higher the ACN, in general, the
heavier the airplane.
>I forgot where I read it but the distribution of weight on a
>MD-80/DC-9 type of aircraft is not as even as, or not as "light"
>as a 747. The 747 has more wheels to spread over its weight
>while the MD-80/DC-9 has fewer to do the same.
I'm not sure what you really mean, but the MD-80 has an ACN of 30 or below,
and the venerable 747-400 has an ACN of over 60. This is not a trivial
difference. There are some airports which must be very careful of where
they allow 747s to operate because they are so heavy. LAX is an example
that comes to mind.
--
Terry
drin...@bcstec.boeing.com
"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."