a series of pilot-scale trafficking trials have been carried out with a wheeled paver on several types of crushed rock and sand and gravel sub-bases complying with the type 1 requirements of the dtp specification; results have been used as a basis for comparing the usefulness of methods of predicting stability of such materials under construction traffic. as expected, simple tests of grading or angularity and descriptions of petrological groups of aggregates were found to be unreliable parameters of stability. cbr tests also gave results which were unsatisfactory for this purpose. although it was found that the established mohr-coulomb shear-strength theory could not be applied to the materials examined, a modified 300 mm shear-box test was found to give a reliable classification of stability of non-plastic sub-bases. a simpler method, based on measurements of decelerations of a drop-hammer device also shows promise.(a)

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