A literature review covering the use of dynamic pile driving equations, wave equation methods, pile analyzers, and current practices by State Transportation Departments is presented. The literature review shows that no one dynamic pile driving formula can be considered superior to all others. However, the Hiley, Janbu, and Gates equations appear to be consistently among the best in published comparisons of formula predictions versus pile load test results. The Engineering News formula and its modified versions are found, with one exception, to be among the worst predictors of pile capacity in these studies. When wave equation methods are included in comparisons of predicted to measured capacity, the wave equation prediction is consistently equal to or better than the best formula. Pile analyzer results can be excellent; however, the ability of the operations is a crucial factor in its successful use.
The majority of the 34 states responding to a survey indicated that they use the Engineering News formula in its original or modified form. No other dynamic equation was mentioned. Several states indicated a switch in recent years from the Engineering News formula to wave equation analyses with a resulting increase in accuracy. Only two states make a regular use of a pile analyzer, but they are very satisfied with it.
Recommendations are made for the improvement of current Washington State Department of Transportation procedures for construction control of pile driving and estimation of pile capacity. Recommendations for additional research are also included.