Converting load into ESALs

[Parkerlax]

I have a road section that is to be subjected to construction traffic for a site yet to be developed. I want to calculate the additional ESALs that the road would be subjected to during construction by the construction trucks delivering construction materials to the site. To simplify my request, please assume these are the only materials that would be hauled to the site to complete the construction:
1. Parking lot area on the site (200ftx250ft)
a. 4 inches of asphalt on 6 inches of CR-6 subbase
2. 4 inches of concrete slab for an area measuring (45 ft by 250ft)
3. Assume 8000 blocks (8-inch masonry blocks)

Please note that these materials are to be brought to the site by tandem-axle trucks. How do I convert the total weight or load into ESALs

 

[Ron]

First of all this reeks of a homework problem..I'll give it the benefit of doubt; however.

A 4-inch concrete slab should not be subjected to high axle loads. In your case, as you've described, your loading is 8000 blocks at, say, 10 lbs each, that's 80,000 lbs. If you put 80,000 lbs on a tandem axle truck, you will be overloaded for most state load limits. Not only does that present an "over the road" issue, it presents an issue with your pavement sections, particularly the rigid section.

To answer your question in its simplest form, you determine the axle loads on the vehicles, go to the AASHTO ESAL tables, and determine the equivalent single axle load (ESAL), with "equivalent" meaning normalized to a standard axle load of 18 kips. You then multiply all of the axle equivalents by the number of anticipated vehicles to get the total load repetitions. This will help you determine the equivalent "years" of use you'll put on the pavement due to the construction traffic.

Be sure to include the unloaded condition as well. A construction delivery truck weighs a lot, so don't neglect the unloaded condition.

I would further suggest that you consult with someone who can sit down and go through this process with you. I have only given an overview...not nearly enough to reach a reasonable solution.

Also, you need to review your problem parameters. Make sure the assumptions you make up front are good ones (loads, number of trips, types of vehicles, etc.)