Project Controls Suite
R-09: Float Erosion Report
Data Date: 28 Feb 2026
Float Erosion Report
4-Period Float Trend Analysis — Metro Line 4 Extension Project
Total Eroding
22
≥ 4d/period loss
Avg Erosion Rate
7.3d
per update period
Worst Erosion
−34d
42d → 8d in 4 periods
New Criticals (3 mo)
7
projected at current rate
Near-Critical Pending
5
TF ≤ 10d currently
4
Activities: TF ≤ 5d
9
Activities: TF 6–20d
9
Activities: TF 21–50d
3
Periods Until Critical (avg)
Float Erosion Register — Sorted by Erosion Rate (Worst First)
| Act ID | Activity Name | Disc. | P−4 TF | P−3 TF | P−2 TF | Current TF | Trend | Rate (d/pd) | Periods →0 | Alert |
|---|---|---|---|---|---|---|---|---|---|---|
| TUN.110 | TBM Launch Chamber Waterproofing | Tunnel | 42 | 29 | 17 | 8 | 11.3 | 0.7 | CRITICAL | |
| CIV.220 | Viaduct Pier Cap Formwork — Section 7 | Civil | 38 | 27 | 16 | 6 | 10.7 | 0.6 | CRITICAL | |
| STR.185 | Steel Deck Erection — Span 4 | Structures | 35 | 26 | 18 | 9 | 8.7 | 1.0 | HIGH | |
| MEP.070 | Station HVAC Ductwork — Platform Level | MEP | 30 | 22 | 14 | 7 | 7.7 | 0.9 | HIGH | |
| ELE.130 | OCS Mast Foundation Concrete | Electrical | 28 | 21 | 15 | 10 | 6.0 | 1.7 | HIGH | |
| TUN.085 | Tunnel Invert Concrete — Zone B | Tunnel | 40 | 34 | 27 | 20 | 6.7 | 3.0 | WATCH | |
| CIV.195 | Retaining Wall Backfill — Depot Access | Civil | 35 | 29 | 23 | 16 | 6.3 | 2.5 | WATCH | |
| STR.200 | Precast Segment Installation — Ring 12–18 | Structures | 44 | 38 | 31 | 23 | 7.0 | 3.3 | WATCH | |
| MEP.050 | Fire Suppression System Installation | MEP | 50 | 44 | 37 | 29 | 7.0 | 4.1 | WATCH | |
| TUN.140 | Secondary Lining — Zone C North | Tunnel | 52 | 46 | 40 | 33 | 6.3 | 5.2 | WATCH |
Showing 10 of 22 eroding activities. TF = Total Float in calendar days. Trend sparklines span 4 update periods (Oct 2025 — Feb 2026). Rate = average float loss per 4-week period.
Root Cause Analysis
TUN.110 (TBM Launch Chamber) is the primary driver — delayed geological survey approval blocked waterproofing subcontractor mobilisation for 6 weeks. CIV.220 is secondary: late rebar delivery across 3 concurrent pier caps compounds float loss on the viaduct sub-network.
Projected New Criticals by May 2026
At current erosion rates, TUN.110 and CIV.220 become critical within 1 update period. STR.185, MEP.070, and ELE.130 will follow within 2 periods. Recommend schedule recovery workshop for Tunnel and Civil packages within 14 days.