| NCHRP 21-03 | Instrumentation for Measuring Scour at Bridge Piers and Abutments | Completed | |
| NCHRP 21-04 | Sealing Geotechnical Exploratory Holes to Protect the Subsurface Environment | Completed | |
| NCHRP 21-05 | Determination of Unknown Subsurface Bridge Foundations | Completed | |
| NCHRP 21-05(2) | Unknown Subsurface Bridge Foundation Testing | Completed | |
| NCHRP 21-06 | Corrosion in the Soil Environment: Soil Resistivity and pH Measurements | Completed | |
| NCHRP 21-07 | Development of Portable Scour Monitoring Equipment | Completed | NCHRP Report 515 Portable Scour Monitoring Equipment |
| NCHRP 21-08 | Assessment of Innovative Load Testing of Deep Foundations | Completed | NCHRP Web-Only Document 84 Innovative Load Testing Systems |
| NCHRP 21-09 | Intelligent Soil Compaction Systems | Completed | NCHRP Report 676 Intelligent Soil Compaction Systems |
| NCHRP 21-10 | Manual on Subsurface Investigations -- Update | Final | The Final Report is available as NCHRP Web-Only Document 258 |
| NCHRP 21-11 | Improved Test Methods and Practices for Characterizing Steel Corrosion Potential of Earthen Materials | Completed | |