Abstract: An extrudable one-way roadway marker (11) is provided having enhanced stability. The roadway marker has a constant cross section along a centerline (A--A) that allows the roadway marker to be manufactured by extrusion. The base (13) of the roadway marker has a series of adjacent parallel grooves (19) that provide a large adhesive surface. A downwardly extending gripping edge (14) assists in attaching the roadway marker to a roadway surface. An inclined surface (23) of the one-way roadway marker receives a reflective tape strip (31) that is protected by a lip (29) lying along the upper edge of the inclined surface. A raised rumble portion (15) provides a physical rumbling cue. The parallel grooves form sharp teeth (21) where they join. The sharp teeth project away from the inclined surface of the roadway marker.