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Military load

Military load

Military load

(OP)
Does anyone know what military load to be used for highway project? Any info as to where i can get that info will be greatly appreciated.

Thanks.

RE: Military load

The AASHTO Alternative Military Loading is two axles separated by 4 feet each weighing 24,000 Pounds.

See AASHTO Standard Specs 3.7.4

RE: Military load

Abrams Tanks weigh 70 tons.  Put that on a draggin waggin and you have one h#** of a load.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Military load

Yeah, a lot like hauling a trackhoe around, as is commonly done.  Seems like you wouldn't have any special loads there, actually.

RE: Military load

JStephen..yep...it's a special load.  70 tons is almost twice the legal limit in most states. But then, you don't see an Abrams being trailered down the interstate very often.

Analyzed a missile haul road a few years ago.  Those missiles are heavy suckers, but the carriers have a bunch of axles and a bezillion tires on them!  Lots of overlapping stresses.

RE: Military load

Could you clarify your request?

Are you designing for the military load per AASHTO or are you envisioning hauling a tank or some other military vehicle over your bridge?

AASHTO Standard Specs 3.7.4 describes the military loading. In LRFD it's not called military loading - it's called Design Tandem, which is two 25kip axles spaced 4-feet apart Plus Lane Load.

If you're hauling a military vehicle that would be a permit vehicle. Your state DOT would have to give you some information then.

RE: Military load

Actually, I believe that the original intent of the interstate highway system, instituted by Eisenhower in the early 50's, was to be able to move military vehicles internally in the event of a national emergency.  So I do not think that the loads are out of the question here.

The only other limitation here besides the load would be the clearances needed too.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Military load

Bridgebuster is correct here too as the 1963 California "Manual of Bridge Design Practice" shows just such a loading on page 3-A-1, referred to as the "Alternative Loading".  It is usually represented to be the double axle situation for a semi trailer.  It is also well to note that a safety factor is NOT included in any of these loads.

The only thing is that you would need a minimum of 7 axles to transport the load under the tank, which is exactly why a draggin waggin has so many axles.  That loading would be substantially different than the "Alternative Loading".

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Military load

I was thinking 70,000 lbs, not 70 tons, when I mentioned the trackhoe.  Looking at the John Deere site, they have trackhoes that weigh 70 tons, but they're bigger than you normally see hauled around, too.

RE: Military load

Mike...you are correct about the original intent of the Interstate Highway system; however, when the designs are done, they typically do not encompass such loads.  When they are transported on the public roads, they are typically trailered on multi-axle, mult-wheeled trailers to spread the load.

Fortunately, a few trips of something very heavy will not usually hurt a pavement.  After all, you could land a 767 on an interstate highway...you just can't do it a hundred times a day for 20 years!

RE: Military load

Right Ron.  The situation would be an emergency where the rules are ignored, for the most part.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

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