The subgrade beneath Singleton Park tells a different story than the alluvium along the Tawe waterfront. One sits on dense Devensian till; the other overlies soft estuarine silts that lose bearing capacity after a wet winter. Swansea receives roughly 1,150 mm of rainfall each year, and that number dictates everything in flexible pavement design. A section that performs perfectly on the upland campus can rut within two seasons if the same granular layer thickness is copied to a riverside scheme. We calibrate every pavement section to the actual CBR and drainage condition of its specific location. The CBR road investigation provides the soaked strength values we need, and grain size analysis confirms whether local borrow material meets the grading envelope for the base course.
A flexible pavement in Swansea is only as good as its subgrade drainage. We design every layer stack from soaked CBR, not from a textbook.
