To determine whether the Washington State Department of Transportation should replace the Engineering News (EN) formula with another dynamic formula for estimating pile capacity, the relative performance of 10 pile-driving formulas was studied. Data were collected from 63 pile load tests conducted in western washington and northwest oregon. The predicted capacity of each pile was calculated using several formulas: Danish, EN, modified EN, Eytelwein, Hiley, Gates, Janbu, Navy-McKay, Pacific Coast uniform building code, and Weisbach. The Gates formula provided the most consistent prediction of pile capacity for each pile type and soil condition analysed. The average predicted pile capacity was compared using the Gates and the EN formulas for different levels of safety. For each level of safety chosen, the Gates formula produced a higher average pile capacity. As the level of required safety increased, so did the difference between the two formula predictions.
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