Model picks, positioning, connections, and inspections quickly. Adjust crew size, efficiency, overlap, and weather factors. Export results for reports, bids, and scheduling clarity always.
| Scenario | Qty | Crew | Per-piece (min) | Pieces/shift | Total hours |
|---|---|---|---|---|---|
| Baseline steel framing | 120 | 6 | 8.95 | 56.7 | 22.1 |
| Higher overlap, better access | 120 | 6 | 8.10 | 62.6 | 20.3 |
| Smaller crew, more delays | 120 | 4 | 10.45 | 48.5 | 26.8 |
1) Base sequential time per piece
Base = Pick + Travel + Position + Connect + Weld + Inspect
2) Overlap-adjusted time
InPlace = Connect + Weld + Inspect
Effective = (Pick + Travel + Position) + InPlace × (1 − Overlap%)
3) Efficiency and rework
Effective = (Effective ÷ Efficiency) × (1 + Rework%)
4) Crew scaling (diminishing returns)
CrewAdjusted = Effective ÷ √(CrewSize)
5) Learning curve
FirstQty = Qty × LearningStart%
LaterQty = Qty − FirstQty
LaterPerPiece = CrewAdjusted × (1 − Learning%)
TotalWork = (CrewAdjusted × FirstQty) + (LaterPerPiece × LaterQty) + Setup + Teardown
6) Delay allowance and shift conversion
TotalWithDelays = TotalWork × (1 + Delay%)
ShiftMinutes = (ShiftHours × 60 − Breaks) × Utilization%
ShiftsNeeded = TotalWithDelays ÷ ShiftMinutes
Cycle time is the combined duration to pick, move, position, and secure each piece. Breaking it into repeatable tasks improves estimating, daily planning, and crew coaching. Use consistent observation periods and record unusual lifts separately. When inputs are stable, the steady per‑piece value becomes a dependable production rate for schedules and bid pricing.
Crane travel and positioning are often the largest drivers on congested sites. Radius changes, blind picks, tag line control, and wind limits add minutes quickly. Reduce travel time with preplanned pick paths, clear laydown zones, and strong radio discipline. Reduce positioning time with temporary guides, match marks, plumb targets, and fit‑up tools at the connection.
Overlap represents real parallel work, such as a connector preparing bolts while the crane is still holding. Apply overlap only where safety, access, and supervision allow. Excess overlap hides constraints and creates optimistic durations. Validate overlap by observing multiple cycles and confirming tasks truly run concurrently without causing rework, waiting, or trade interference.
Efficiency converts ideal minutes into field‑realistic time. Access, lighting, supervision, material readiness, and lift sequencing shift efficiency up or down. Rework adds time for misalignment, incorrect hardware, or weld repairs. Delay allowance captures coordination pauses, permits, inspections, and weather. Track these factors weekly, then update inputs instead of forcing the schedule.
Shift modeling links cycle time to deliverable output. Available minutes equal shift hours minus breaks, multiplied by utilization. Utilization should reflect toolbox talks, movement between work fronts, and minor interruptions. Pieces per shift and shifts needed support look‑ahead plans, manpower leveling, and realistic milestones. Export results to document assumptions and align stakeholders. For multi‑zone projects, run separate scenarios for each work front and combine them. Keep a short log of actual cycles, then compare planned versus actual to identify bottlenecks. Small improvements in positioning or connection time compound across hundreds of pieces every week.
1) What should I use for efficiency?
Start with 70–90% for typical field erection. Use higher values only when access, material readiness, and supervision are strong. Calibrate by timing several cycles and adjusting until predicted pieces per shift matches actual output.
2) How do I choose an overlap percentage?
Only apply overlap when tasks truly run in parallel, such as bolt preparation during crane hold. Verify by observing complete cycles. If overlap creates waiting, congestion, or safety conflicts, reduce it to a conservative value.
3) Why does crew size scale by square root?
Adding people helps, but coordination and limited work faces reduce the benefit. The square‑root rule provides a practical diminishing‑returns approximation. For specialized crews, validate with measured production rates and adjust inputs to match site behavior.
4) When should I include rework?
Include rework when fit‑up issues, missing hardware, alignment corrections, or weld repairs are common. Use a small percentage for controlled work and a higher percentage for first‑time assemblies or complex geometry. Update it as quality improves.
5) How do I model breaks and utilization?
Enter total break minutes per shift, then set utilization to reflect toolbox talks, travel between areas, and minor interruptions. Many teams use 80–95%. If you track productive time, set utilization to match your measured daily reality.
6) Can I use hours instead of minutes?
Yes. Select hours as the input unit, then enter task times in hours. The calculator converts internally and returns consistent results. For clarity, keep all task inputs in the same unit and document assumptions in the exported report.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.