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Re: Design of Pavement Section

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Lloyd Pack <packman90(--nospam--at)> wrote:

You will probably find that an asphalt section will be less expensive, unless
labor for excavation is very high. There is quite a large difference in the
roadway section for different soils capacities in the subgrade material. It
would be best to have a Geotechnical Engineer give you some recommendations
or at least some R-values or CBR numbers to design the section from.

Where I'm working, we often get R-values in the 7-50 range. Seven is very low
but we've got some clayey or silty sands here (old farmground - good for farming
not so good for roads) With the low R-value material we have a highly travelled
5-lane road that has a section of 3 ft., 22" sub-base, 8" roadbase, and 6" asphalt.

For the standard highway district road section or local city road section, they use
12" roadbase and 3" asphalt. For a driveway that will see very infrequent heavy
truck loading, you might be able to get by with 8" roadbase and 2.5-3" asphalt, again
depending on the sub-grade soil strength. I've seen some soils that were good
enough to pave the 3" or 2.5" of asphalt right over the existing ground. (after
scraping off the topsoil, of course)

I hope that this helps. It looks like you've got many other responses about
concrete so I won't touch on that.

Take Care,
Lloyd Pack

On 20 Dec 2007 at 13:27, Bill Allen wrote:

> Don?t ask me why, but I need to design a driveway (on grade) for a
> fire truck. I believe the owner wants to use AC, but if he must go
> with PCC, then he will.
> Are there any good guidelines, references, methods used to design a
> section for this purpose? I sure would hate to waste a bunch of time
> if this is something that is pretty simple.
> I?m supposed to be receiving wheel loads later today.
> TIA,
> T. William (Bill) Allen, S.E.
> Consulting Structural Engineers
> V (949) 248-8588 ¢ F(949) 209-2509

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