Kerf is an outdoor series of two pigmented cast concrete sculptures by Thomas Sayre, installed at the MAX Orange Line's Southeast Tacoma/Johnson Creek station in the southeast Portland, Oregon portion of the Ardenwald-Johnson Creek neighborhood, which straddles the border between Portland (and Multnomah County) and Milwaukie, Oregon (and Clackamas County).
According to TriMet, the pieces were "earth-cast" on site and represent "the influence of wheels on the area, from a 19th-century sawmill on Johnson Creek to the wheels of the MAX train".