this report is an appraisal of the compaction currently being achieved in pavement layers constructed with dense coated macadams in the united kingdom. cores were removed from 12 newly constructed major roads. densities of the compacted material were found by direct transmission of gamma rays through cores and also by in-situ use of a gamma-ray back-scatter gauge. compaction is expressed in terms of density, void content and voids in the mineral aggregate (vma). the effect of material composition on compaction is considered for all sites and a detailed assessment is made of the effect of laying and compaction procedures in the case of 7 sites where construction was observed. ninety per cent of the values of void content were in the range from 2 to 8 per cent whereas the corresponding range of values of vma was considerably narrower, from 13 to 16 per cent. an examination of the rolling procedures indicated that there is scope for increasing the level of compaction in the position of the nearside wheel path. further cores will be removed 12 months after the roads were opened to determine the extent of further densification under traffic.(a)

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