tandem vs. tridem axle config

We have a road in which someone has hauled repetitive loads, while not using third axle (Making him illegally loaded). Does anyone know the calculated difference (or how to calculate) in damage caused by a typical dump truck not using the third axle vs. using it. The gross weight of the truck is 80 kips. Thanks in advance for any help.

damage to I am a Gigantic DoucheBag

typical HS-20 axle load is 32kips

tandem on 80 kips is 40 kips/axle or 25% overload.

AASHTO standard code design load factor for an HS-20 live load would be 2.17 + impact.

your truck is overloaded but not crazy. Again what damage are you talking about?

^^ I think this kind of damage:


:bananapowerslide:

For a triaxle, the GVW is usually 80k. However, the law in your jurisdiction may limit the legal weight to less than the GVW.

To ballbark it, figure the front axle carries 20k max, leaving 60k on the rear axles. Therefore with the third axle down, each is carrying 20k (60k/3 axles). If the third axle is up, you would have 60k/2 alxes = 30k per axle.

I'm not sure what you mean by damages either. There should be laws/regulations in your area related to this. Is it a private road? If so, I'd think it would be difficult to quantify any potential damages such as shortened pavement life.

Andrew

I apoligize for the delay in reply. I should have phrased the question a bit better. There are isolated base failures and where these failures occured there was water standing in the ditches (the roadway is pumping). I am just curious if these failures would have been avoided if the driver was using the 3rd axle. What I am looking for is the typical loading of a tandem and a tridem (how much of the weight is carried by the front axle or all axles are assumed equal?)

of course all trucks are different but typically the front axle under the cab is significantly lighter than the rear axles under the load. A standard H-20 truck is an 8k front axle with a 32k rear axle. The design tandem assumes a 4 ft spacing between two 25k axles under the loaded part of the truck.

The company I work for runs a fleet of triaxles. We are allowed up to 73,280 GVW here in PA. We often get checked by the state, and sometimes they check the loading on each axle. From what I have seen on our trixles, when loaded (73k) you usually have about 15k on the front axle, and 58k on the rear axles, which is spread fairly evenly.

It sounds like the road had some issues prior to the hauling. I don't think there is a way to prove whether the third axle issue caused the failures exclusively, but I'm sure it did not help.

kevo_55 said:

^^ I think this kind of damage:

Click to expand...

Yikes!

Quest:

How many repeated impacts can a railroad overpass take before failure under use?

error_matrix said:

Yikes!Quest:

How many repeated impacts can a railroad overpass take before failure under use?

Click to expand...

The bigger question is, how many levels of government must be visited to cut the pavement down 6" so no one gets hurt or worse, killed.