How to estimate ESAls for crane

[gwkwong]

I am working on a asphalt pavement design within a plant. I would like to know how to estimate ESALs for crane. I have trouble finding information about crane ESALs on the web page.

http://files.engineering.com/getfil...af-02899d5f3a95&file=200_&_300_tone_crane.pdf

http://files.engineering.com/getfil...8-945f7af57477&file=SKMBT_C45109060113480.pdf

 

[Ron]

You will have to create you're own equivalence chart by axle. Get the loaded weight of each axle and compare that to a single 18k axle based on the ESAL tables. If your axle loads are off the scale of the ESAL tables, develop a curve and extrapolate.

In your attachment, it looks as though the axles are fairly close together, so you might have to use the tandem ESAL chart as well and do your table in pairs of tandems. Then compare the two.

After you do that and develop your own table of loads, check the stresses in the pavement layers using elastic layer analysis.

I did one very similar to this for a military application a couple of years ago. I will see if I can pull the report and send you an example of the table.

 

[gwkwong]

The file attached shown the axle loads and distance between center. So What you means is to check with the AASHTO pavement impact load equivalency chart (I think is under Guide for design pavement structures, Appendx D, table D-4 and D-7. Then just pick the ESALs number based on the type of axle (single or tandem). Am I correct. If you don't mind, I would really like to take a look at how you come up with your results which you did a few years back.

Also, one crane has 4 axles which are very close together. They fall into the tandem axle category. However, I am not sure in this case, if I should treat them as 3 sets of tandem axles or 2 sets.

 

[Ron]

Yes. You got it.

I would treat them as 3 sets of tandems so that you can pick up the potential overlap of stresses.

If you treat them as 4 individual axles, you'll be very conservative in your thickness estimates.

Attached is an example of a table you can develop.

 

[gwkwong]

Ron,
Thanks for your information. I was talking to Alberta Transportation. They said they don't use ESALs for heavy wheel load. They told me to look into "Asphalt Pavements for Heavy wheel loads" by Asphlat Institute. What is your though on that.

 

[Ron]

That's essentially the elastic layer method I mentioned before.