The A2070 link road near Ashford carries heavy goods vehicles daily, and the pavement structure has to cope with both traffic loading and the underlying Weald Clay. When we started the pavement assessment for a new industrial estate off Ellingham Way, the contractor was surprised by the variation in subgrade stiffness across the site. In Ashford the superficial geology shifts between Head Brickearth, river gravels and the sticky Weald Clay, so a single pavement cross-section rarely works for an entire development. We ran a series of dynamic cone penetrometer checks and laboratory CBR tests to feed into the flexible pavement design, following the DMRB CD 225 and BS EN 1997-2 approach for deriving modulus values. Understanding Ashford’s post-glacial deposits makes the difference between a pavement that ruts after two winters and one that stays smooth for a decade.
Ashford’s Weald Clay subgrade loses more than half its stiffness between summer and winter — pavement design has to reflect that seasonal swing.
