Controlling the Installation of Driven Piles

During pile installation it is imperative to ensure reliable, repeatable, efficient, and accurate methods are utilized to verify the resistance of driven piles and ensure the pile resistance satisfies the design requirements.   

The MTO currently employs a customized version of the Hiley Dynamic Formula on its projects to control pile installation and to monitor/verify the axial capacity of the pile during installation. However, the accuracy of the MTO Hiley Dynamic Formula has been challenged on MTO projects.  Also, the inconsistency of the MTO Hiley Dynamic Formula from pile to pile and from site to site has led to discussions regarding the validity of the application of the formula on MTO projects. 

A comprehensive study, which reviewed the installation and testing of 299 piles at 34 different sites between 1979 and 2022, has been completed to compare the accuracy, efficiency, and reliability of high strain dynamic testing (Pile Driving Analyzer or PDA) with the MTO Hiley Dynamic Formula. The study included a comparison of each method with static pile load testing and with predicted static empirical methods on MTO projects. The study concluded that the PDA is a more reliable and dependable method of controlling pile installation.

The MTO intends to use PDA testing as the primary methodology for controlling the installation of driven piles on MTO projects. Use of the MTO Hiley Dynamic Formula will only be allowed on an exception basis.