Skip to Main Content


The term ground investigation refers specifically to the investigation of subxsurface soil, rock and groundwater conditions, either through intrusive methods (principally boreholes and trial pits and the associated soil/rock sampling and testing) or surface and borehole geophysics. Ground investigation methods are described in numerous textbooks including more recently Clayton et al. (1995), Simons et al. (2002), Cornforth (2005) and Bond & Harris (2008), for example.

Ground investigations for low-cost roads can often be low on the priority list. They are sometimes seen to be costly and time consuming, providing little information of any value. However, if planned and implemented correctly, they can yield valuable information when compared to the cost of design.

Ground investigations are undertaken for new roads to determine:

  • typical soil and rock profiles to calibrate and augment the terrain models, terrain classifications and field mapping referred to earlier (Sections B2 & B3);

  • specific soil and rock profiles in the case of deep cuts for site-specific design;

  • foundations for structures, such as bridge piers and abutments and large retaining walls;

  • depth and geotechnical composition of existing landslides and the design of remedial works; and

  • material type and depth for borrow areas.

Ground investigations are undertaken for existing roads when examining:
  • landslides that were not stabilized during construction; and

  • new landslides and road failures that have occurred since construction.

In all cases, desk studies and

You do not currently have access to this chapter.

Figures & Tables





Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal