TBM Advance Rate Calculator for Tunnel Construction Progress

Input Form

Use the fields below to estimate TBM advance rate, short-term productivity, and approximate completion duration.

Project Label

Tunnel Length (m)

Penetration (mm/rev)

Cutterhead RPM

Utilization Factor (%)

Operating Hours per Day

Working Days per Week

Site Efficiency (%)

Geological Delay Allowance (%)

Reset

Plotly Graph

The chart below shows projected cumulative tunnel advance by week. Example data appears until you submit your own values.

Example Data Table

This example uses a 3,200 m tunnel, 8 mm/rev penetration, 7.5 RPM, 65% utilization, 18 operating hours, 6 working days, 90% site efficiency, and 8% geological delay.

Scenario	Tunnel Length (m)	Penetration (mm/rev)	RPM	Utilization (%)	Daily Advance (m/day)	Weekly Advance (m/week)	Completion (months)
Main Tunnel Drive	3200	8.0	7.5	65	34.877	209.261	3.52
Conservative Ground	3200	6.5	6.8	58	23.047	138.282	5.33
Optimized Shift Plan	3200	8.8	8.0	72	49.752	298.512	2.47

Formula Used

1) Theoretical Hourly Advance

Theoretical Hourly Advance (m/h) = Penetration (mm/rev) × RPM × 60 ÷ 1000

2) Net Hourly Advance

Net Hourly Advance = Theoretical Hourly Advance × Utilization Factor

3) Adjusted Hourly Advance

Adjusted Hourly Advance = Net Hourly Advance × Site Efficiency × (1 − Geological Delay)

4) Daily and Weekly Advance

Daily Advance = Adjusted Hourly Advance × Operating Hours per Day
Weekly Advance = Daily Advance × Working Days per Week

5) Estimated Duration

Working Days to Complete = Tunnel Length ÷ Daily Advance

How to Use This Calculator

Enter the tunnel length for the drive you want to estimate.
Provide penetration per revolution from TBM performance records or planning assumptions.
Enter the cutterhead RPM expected for the geology and tool condition.
Set utilization to reflect actual boring share within the operating window.
Fill operating hours per day and working days per week.
Apply site efficiency to include logistics, staffing, ring build, and coordination effects.
Add geological delay allowance for difficult ground, interventions, or expected disruptions.
Press calculate to view advance rate, duration, export options, and the projection chart.

Frequently Asked Questions

1) What is TBM advance rate?

TBM advance rate is the estimated tunnel length a tunnel boring machine can excavate over time. It is usually expressed in meters per hour, day, week, or month.

2) Why do penetration and RPM matter?

Penetration shows how much distance the machine gains per revolution. RPM shows how many revolutions happen each minute. Together, they define the theoretical cutting speed.

3) What does utilization factor represent?

Utilization reflects how much of the scheduled operating window is spent on actual boring. It accounts for breaks, maintenance, checks, ring installation, and non-cutting stoppages.

4) Why is site efficiency separate from utilization?

Site efficiency gives another planning adjustment for crew coordination, muck handling, supply chain, alignment work, and support systems. It helps refine production beyond pure cutting time.

5) What does geological delay allowance do?

Geological delay allowance reduces the projected rate to reflect expected disruption from variable ground, water ingress, fault zones, tool wear, and additional treatment work.

6) Can this estimate total tunnel duration?

Yes. The calculator divides tunnel length by adjusted daily or weekly advance to estimate working days, calendar weeks, and approximate calendar months.

7) Is the monthly output exact?

No. Monthly output is an approximation based on average weekly progress multiplied by 4.345. Real project calendars, shutdowns, and access constraints may change outcomes.

8) When should I update the inputs?

Update inputs whenever geology changes, cutters wear differently, shifts are revised, downtime trends change, or you receive fresh production records from field monitoring.