It is an assessment process of the subgrade layer before installing overlying pavement layers. It is a visual assessment to confirm whether it will enable the construction of the subsequent pavement layers.

There are various ways, one is a smooth-drum roller, and it is one of the best ways that everybody commonly uses it. Another way we follow is a fully laden truck or water with a single axle with a lot of load on the wheels.

Engineers will walk alongside the roller as it moves forward over the completed subgrade to see if there is any deformation. It is method of testing the subgrade entire subgrade whereas other test methods such Field Density Tests (FDT) are limited to small area. This quick & inexpensive visual assessment conducted by geotechnical engineers.

About eight tonne single axle trucks are used over the prepared surface to know whether there is any deflection of the surface. It is an essential step in quality control.