1. Inadequate Foundation Compaction
Error Phenomenon: Substandard compaction (<90% Proctor density) observed in 2018 Texas DOT Project I-35W (Case No. TXDOT-2018-047) resulting in 12cm settlement.
Consequence Analysis:
- CSA S6-14 Risk Level: 4 (High)
- Structural deformation exceeding ASTM A796 §6.2.3 tolerance limits
- Accelerated corrosion at stress points (see Fig.1: corrosion rate ↑300% at 85% compaction)
Corrective Measures:
- Over-excavate 300mm and recompact with ≤5% moisture content
- Nuclear density testing every 20m (AASHTO T310)
Prevention Checklist:
☑ Verify CBR ≥8% prior to pipe placement
☑ Achieve 95%±2% compaction for Zone 1 (AASHTO M36 Table 8-3)
☑ Conduct proof rolling with 200 kN/m² load
Field Note: BC Ministry of Transportation requires dual-stage compaction for organic soils (Standard Spec. 203.05).
2. Misaligned Joint Installation
Error Phenomenon: 25mm offset exceeding ASTM D4070 §4.1.2 maximum 6mm tolerance (2016 Manitoba Hydro case study).
Standard vs Faulty Practice:
ParameterFaulty PracticeASTM StandardJoint Gap15mm3±1mmGasket Compression30%40-60%
NSPE Ethics Reference: §II.1.c – “Engineers shall approve only work conforming to applicable standards.”