| Excavation Technique | L (km) | <0.3 km | 0.5 km | 1.0 km | >1.5 km |
| Manual Excavation | Acceptable | Avoid | Not acceptable | ||
| Plant/Mechanical | Acceptable | Avoid | |||
| TBM Machine | Avoid | Acceptable | |||
| Drill & Blast | Avoid | Acceptable | |||