When using roadway and traffic standards developed for foundations from TCP information (COSS, High Mast Illumination Poles), use the following correlations (from Touma and Reese, 1972) from SPT values acquired in the drilled boring logs:

In Clay: N

TCP

= 1.5 * N

SPT

In Sand: N

TCP

= 2.0 * N

SPT

Where, N

TCP

= equivalent TCP blow counts when using STP information

N

SPT

= uncorrected blow counts from STP in-situ testing

These correlations apply to the standard foundation embedment selection charts regarding TCP information currently refenced in the standards.