calculating external forces on buried PVC conduit

[k2panman]

The National Electrical Safety Code requires buried conduit to be "designed to withstand external forces to which it may be subjected..." The code says that live load in a roadway shall be the weight of a moving truck, which it gives a diagram to use showing the design forces and area of each tire footprint. Can anyone recommend a good place for an electrical engineer (me) to find an easy to understand way to calculate the forces and strength of the installed conduit? I'm using 4" schedule 40 PVC.

K2ofKeyLargo

 

[RWF7437]

try this link

http://www.plasticpipe.org/index01.php

good luck

 

[RWF7437]

or this

http://www.uni-bell.org/

 

[SlideRuleEra]

Here is a direct link

http://www.pwpipe.com/pdf/tb-d5.pdf

http://www.SlideRuleEra.net

 

[k2panman]

Thanks for the help!

K2ofKeyLargo

 

[DRC1]

I have only seen RMC - rigid metal conduit - undr roadways.

 

[kyruby]

I work for an electric utility and we require all conduit under a roadway or any paved surface to be either concrete encased with 6" minimum surround or the installation of rigid metallic conduit. If it happens to be a major highway crossing with multiple circuits we will require a concrete duct bank installation.