Blenheim's expansion from a small river settlement into Marlborough's main urban centre has placed increasing demands on its road network. The Wairau River floodplain provides the city's foundation, but it also delivers challenging subgrade conditions: silty alluvium, variable groundwater, and pockets of uncompacted historic fill. Designing a flexible pavement that survives two decades of traffic without rutting or fatigue cracking requires more than a standard cross-section. It demands a granular understanding of local subgrade behaviour under repeated loading. Our technical team has been involved in pavement investigations from the Springlands industrial area to the new subdivisions around Witherlea, working directly with civil contractors and development engineers. We combine laboratory CBR values with field density verification to produce pavement designs that meet NZS 4404:2010 and local council engineering standards, ensuring each layer contributes to the long-term structural capacity without over-designing and wasting project budget.
A soaked CBR of 3% versus 8% can double your required pavement thickness. In Blenheim's silty floodplain soils, that difference is often found within a single subdivision.
