A method of marking a curved median with a passive elongated flexible roadway marking device entails bending the device to conform to the curved bullnose shape of a roadway median, adhesively attaching the device to the surface of the median and then mechanically fastening the device to the median. Bending notches with stress relief vertices may be provided in a flange of the spline to facilitate concave bending of that flange. Attachment holes may be provided in flanges of the spline, in an alternating arrangement. Spaced apart retro-reflective tape strips are applied to the curved outer surface of the protrusion.