Thermoplastic polymers, rubbery polymeric components and reinforcing
fillers are mixed and heated to a range of 380.degree. F. to 440.degree.
F. The resulting mixture is then fed into a Banbury mixer, with the
resulting mixture fed into a diverter feeding two molds. The velocity of
the piston of each mold being filled is controlled to thereby control the
density of the molded product along its length. As each mold is filled,
it is deposited in a cool water bath (50.degree. F.-60.degree. F.) while
the next mold is being filled. The molds are sequentially transferred to
an air cooling rack to complete the process. A texture, generally
comprising indentations perpendicular to the longitudinal axis on the
molded object, provides a frictional surface between the railway crosstie
and the ballast beneath the crosstie.