open-textured macadam surfacings to bs 1621 were laid in 1962 on trunk road a30 at blackbushe using 300 pen bitumen, and crushed-rock aggregates from six sources. all the roadstones gave materials which remained in good condition for at least five years and the best were still good after ten years' service. the surfacings were studied for resistance to skidding by regularly measuring sfc50s and texture depths. it was concluded that for long life with a good resistance to skidding on a road carrying approximately 2000 c.v.d. per lane, the aggregate used must be selected carefully as regards psv, aav and rock-type, and the macadam must be laid on a sound structure. (a)

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