In-situ testing is useful where soft soils, variable fill, groundwater, or difficult access conditions make conventional SPT-based correlations less reliable. It can also help reduce uncertainty when design assumptions are driving conservative recommendations or expensive construction decisions.
Use CPT when continuous stratigraphy matters
Cone penetration testing can identify thin layers, soft zones, and transitions that may be missed between conventional boring samples. That continuous profile is especially valuable for embankments, settlement-sensitive structures, pavement subgrades, and sites with variable fill or alluvial deposits.
Use pressuremeter testing for deformation parameters
Pressuremeter testing can support foundation and retaining wall design where stiffness and deformation behavior are important. The test can provide project-specific modulus information that helps engineers move beyond broad correlations when subsurface conditions justify the added effort.
Use supplemental testing to focus recommendations
The goal is not to add tests for their own sake. The value comes when additional data changes a design decision, reduces uncertainty, or confirms a more practical construction approach. Reference projects such as I-895 show how supplemental CPT data can materially change assumptions for strength, modulus, and capacity.
- Use CPT to refine stratigraphy.
- Use pressuremeter testing where deformation parameters matter.
- Use supplemental data only when it supports a specific design decision.