What does "equate" mean?

Equate: To make equal; to reduce to an average; to make such an allowance or correction in as will reduce to a common standard of comparison; to reduce to mean time or motion; as, to equate payments; to equate lines of railroad for grades or curves; equated distances. Palgrave gives both scrolle and scrowe and equates both to F[rench] rolle. Skeat (Etymol. Dict. ). Equating for grades (Railroad Engin.), adding to the measured distance one mile for each twenty feet of ascent. -- Equating for curves, adding half a mile for each 360 degrees of curvature.