How do I translate ESAL to H-loading?
How do I translate ESAL to H-loading?
(OP)
I have a pavement manufacturer that has performed an accelerated wear test on a product we'd like to use in Los Angeles County but our Fire Department is requiring us to use only pavement products that are capable of H20 loading. The problem is that the engineering documentation from the pavement manufacturer used ESAL units in their testing (as I believe they should for pavement wear testing). Still, I have to come up with some sort of way to demonstrate how I can translate ESAL units to either show matching or exceeding H20 loading requirements I'm working under. Is this even possible? From what I understand, H-loading is a specific imaginary vehicle of a certain weight and dimension but ESAL units are based on a quantity of axles of a certain weight over a period of time. Am I in an impossible situation with this?
Any help would be great and I'm so glad I found this forum!!
Any help would be great and I'm so glad I found this forum!!





RE: How do I translate ESAL to H-loading?
H20 is a standard bridge loading. It has an 8000lb front axle load and either a single 24000lb rear axle load or two, 16000lb rear axles spaced 4 feet apart.
Using the AASHTO ESAL load tables, you can back into the equivalent single axle loads for one standard H20 loading.
Roughly, for the tandem axle loading, one standard H20 loading is equivalent to 0.879 ESAL, while the single axle loading condition for the standard H20 is equivalent to 3.79 ESAL. As you can see, any axle loading greater than 18000lb runs the ESAL up quickly.
RE: How do I translate ESAL to H-loading?
http://www.tfhrc.gov/structur/pubs/04098/11.htm
My problem is that, after further reading, the engineering white papers from the pavement we're wanting to use had 18,000 lbs per axles (18 kip ESALs). If you can show me some documentation that says I can divide that load into TWO 16,000 axle loads, I'd be in great shape!
Thx for the help so far!!
--Jon Roberts
Land Tech Engineering
Southern California
RE: How do I translate ESAL to H-loading?
Good luck.
Ron
RE: How do I translate ESAL to H-loading?
--Jon Roberts
Land Tech Engineering
Southern California
RE: How do I translate ESAL to H-loading?
Most states limit single axle loads to 24000 lb and 32000 to 34000 lb for tandems (two axles at 16000 to 17000 lb each). Two 32000 lb tandems would greatly exceed allowable state highway loadings.
The H20 designation comes from the AASHTO Standard Specifications for Highway Bridges, not the AASHTO Design of Pavement Structures Manual. The Pavement Structures Manual bases all designs on an Equivalent Single Axle Load (ESAL) with the "standard" axle load being 18000 lb. All other loads on the axles are compared to that standard and each is rated based in its ratio of load, either higher or lower.
You are correct in your original post that you are somewhat comparing apples and oranges; however, depending on how they presented their data, you might still be able to correlate. The difference is that you want to know if the device can withstand 1 loading of the H20 designation and they are telling you how many times the device will withstand an 18k standard load. I see your dilemma...you might want to see if you can get more info from them. You will have to back into the correlation from material property and fatigue data.
RE: How do I translate ESAL to H-loading?
Thanks again everyone. I've learned a lot through dealing with this!
--Jon Roberts
Land Tech Engineering
Southern California
RE: How do I translate ESAL to H-loading?
Almost any pavement section will withstand one pass of a 32k axle load, but it takes a properly designed section to accommodate one or two million repetitions of same.
Ron
RE: How do I translate ESAL to H-loading?
--Jon Roberts
Land Tech Engineering
Southern California
RE: How do I translate ESAL to H-loading?
Ron