The solidity of bridge piers built on pilings depends largely on how deep the pilings are driven. Prior to 1700, pil...

Victoria on May 9, 2019

Hi @Shiyi-Zhang,

The passage states that, at the time that this bridge was constructed, "the contemporary standard for refusal was to drive the pilings until additional penetration into the ground was no greater than two inches after twenty-four hammer blows."

This means that the piling was considered driven deep enough if it did not move more than two inches following twenty-four hammer blows. However, this also means that the pilings could still be considered to meet the standard of refusal if they moved by any amount less than two inches following twenty-four hammer blows. This makes it possible that the pilings could have been driven deeper into the ground (by less than two inches) even after the standard of refusal was met.

Hope this is helpful! Let us know if you have any further questions.