Abstract
A study is described in which interim guidelines were developed for designing bridge pier riprap protection. Based on experimental data two procedures were developed to determine the size of riprap needed to protect bridge piers from local scour. The primary procedureis represented by equations. This accounts for the influence of a preexisting scour hole which tends to downsize the riprap requirements. A second procedure is presented, also represented by an equation, and is a refinement of the interim guidelines in the fhwa's hec-18.This procedure is simpler and is applicable for most bridge piers where the riprap final placement will be approximately flush with thestreambed.