Current TxDOT practice is to use the Load and Resistance Factor Design (LRFD) methodology for foundation design whenever practical and in accordance with AASHTO LRFD Bridge Design Specifications (current edition) and applicable Federal Highway Administration (FHWA) reference materials. This reliability-based design methodology (compared to the former TCP driven design correlations) creates greater utility for the state by accounting for a uniform level of reliability due to multiple factors and allowing for local calibration of factors depending on level of confidence through research. The basic equation for this method is:

∑ηiγiQi ≤ ϕR

n

= R

r

Where: η

i

= a factor that includes the effects of ductility, redundancy, and importance

γ

i

= the load factor for a particular load

Q

i

= a service level load

ϕ = the resistance factor

R

n

= the nominal (i.e., ultimate) resistance

R

r

= the factored resistance

Proper foundation design requires communication between the geotechnical engineer and the structural engineer with consideration of data collected to address what information is needed along with when and how information will be exchanged.