Pavement Bearing Capacity

[EdMartin]

Hi all. I'm a general Civil Engineer & new to the forum. Doing a project with a private drive. Design vehicle will be a 75,000 lb fire truck. Client wants thinnest possible pavement cross-section. Town is willing to deviate from their typical detail, but wants documentation that our proposed pavement has at least the design vehicle bearing capacity. We're planning on 9-inches of compacted stone (2-lifts), 2-inches of binder, and 1-inch of top course. Can someone help with the appropriate equation(s) demonstrating the proposed cross-sections bearing capacity? I have never designed pavement, so don't assume I have any prior knowledge/understanding of the intricacies of the process/calculations.

Thanks in advance!

 

[Hoaokapohaku]

You will probably find this overview will point you in the right direction

http://design.transportation.org/Do...anistic-EmpiricalDeisgnProcedure-Volume2.pdf.

 

[Ron]

Pavements are not really designed on a "bearing capacity" basis. The designs are based on repetitions of loads. The pavement section you described, assuming the "stone" layer is a well graded material that achieves stability when compacted, will withstand relatively high loads, assuming the number of repetitions is low (low frequency of traffic for the high wheel or axle loads). If you want to go through the exercise of justifying the section, use either the AASHTO Pavement Design Guide or any one of several states that have design guides based on the AASHTO manual (Florida, Iowa, Ohio, Washington, etc.). The state design guides are often available online.

 

[dicksewerrat]

What is under the stone?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[BenJohnson]

Pavement can fail due to many causes. If you are not fully trained and skilled to be redesigning a roadway then you have an obligation to tell the client that you are not the right person to be trying to change City Standards.

There is no shame in saying that. Try reading and understanding the link that Hoaokapohaku provided. Alternative pavement design requires someone who specializes in this field. That's why the City has Standard Designs - for the engineer who is a "generalist" (such as yourself).

I sure would want my name (and license) on any document that portents demonstrate an alternative design is equal to City Standards.

 

[cr1973]

3" of asphalt does not sound like a good paving solution in this case.

 

[EdMartin]

Thanks all for your input. After awakening from my AASHTO induced coma, I advised my client that I was in no position to alter the standard pavement cross-section.

 

[BenJohnson]

Perfect.