Tunnel boring machines · gripper and shielded rock TBMs, EPB and slurry (Mixshield) soft-ground machines, selection by fines content and water pressure, penetration rate versus utilization, diameter ranges
A tunnel boring machine (TBM) excavates a full circular tunnel face with a rotating cutterhead, pushes itself forward on grippers braced against rock or on thrust cylinders against the lining it has just built, and removes spoil and installs support from a trailing back-up train. Ask three things first: which machine family suits the ground and groundwater along the whole drive, what advance rate is realistic once downtime is counted, and what diameter, thrust, torque and lining system the tunnel needs.
Full-face tunnel boring machines for rock (open gripper/main beam, single and double shield) and soft ground (earth pressure balance, slurry and mixed shields) for road, rail, metro, water and utility tunnels. Roadheaders, pipe-jacking and microtunnelling machines, and TBM components sold alone such as bearings, cylinders and cutters are outside this page except where compared.
Start with your task
01
The FHWA Technical Manual for Design and Construction of Road Tunnels divides rock TBMs into open gripper/main-beam machines, for stable to friable rock with occasional fractured zones and controllable water inflows, and closed (shielded) machines, single shield, double shield or gripper shield, for friable to unstable rock that cannot take gripper pressure; it notes these rock shields are not pressurised at the face and cannot handle high external water pressure. A TBM's main body carries the cutterhead, grippers or shield, thrust cylinders, conveyor and rock reinforcement equipment, and a fully equipped TBM with its trailing system can occupy over 1,000 ft of tunnel. [1]
For soft ground the manual describes pressurised closed-face machines: earth pressure balance (EPB) machines, which use a screw discharger to form a plug and hold face pressure, suited to clays and clayey or silty sands below the water table; and slurry face machines (SFM), which support the face with pressurised slurry and suit water-bearing silts and sands with fine gravel. It states that with more than 20% fines an SFM becomes questionable because separating spoil from slurry becomes difficult, that below 10% fines an EPB may be unfavourable and needs more conditioning, that sticky high-plasticity clays cause problems for both, and that mixed ground may need a dual-mode machine. [1]
Herrenknecht's ranges illustrate the two families: EPB shields of 1.7 to 16 m for soft, cohesive soils (clay, silt, loam, low permeability), and Mixshields of 4 to 19 m for sandy, gravelly and heterogeneous ground with high permeability, with an air cushion regulating face support and use at water pressures above 15 bar. [2] [3]
Give the supplier the geological and hydrogeological profile along the drive (soil grading and fines content, plasticity, rock strength and abrasivity, water pressure and permeability), tunnel diameter and length, curve radii and gradients, lining type and segment design, settlement limits and structures above, launch and reception shafts, spoil handling and disposal, power available, and programme.
02
FHWA lists the factors that set a rock TBM's penetration rate, total thrust, cutter spacing, diameter and edge geometry, cutterhead speed and torque, tunnel diameter, and rock strength, hardness, abrasivity and jointing, and warns that penetration rate alone does not give a high average advance: actual cutting time is cut by start-up learning, cutter changes, repairs, back-up systems, ground support, muck and water handling, probe drilling and grouting, so "actual utilization typically runs in the range of 50%". [1]
Editorial calculation: a machine penetrating 2.5 m per hour of boring, working 24 hours a day at 50% utilization, advances about 2.5 × 24 × 0.5 = 30 m a day; a 6 km drive at that rate takes about 200 working days, before launch, breakthrough and stoppages. Penetration rate and drive length are assumed examples; base estimates on the ground data and the supplier's performance prediction.
03
The listings kept include tunnel boring machines in a crushing and construction machinery range, and earth pressure balance and slurry TBMs from an automation equipment trader. Ask any TBM supplier for the machine family, diameter, thrust, torque, cutterhead design and back-up system, and for references in similar ground.
04
The Robbins Company states that its Main Beam TBMs are suitable for competent to slightly fractured rock and are designed to each tunnel's specifications in diameters from 3 to 15 m (10 to 50 ft). The rotating cutterhead matches the tunnel diameter and holds disc cutters of 14 to 20 in; hydraulic propel cylinders push the cutters into the rock while a floating gripper system braces on the sidewalls, so the machine can be steered continuously. Buckets in the cutterhead drop muck onto a belt conveyor inside the main beam. [4]
Robbins says the open design gives access directly behind the cutterhead for rock bolts, steel mesh, ring beams and shotcrete, which suits unlined tunnels, and that its Main Beam TBMs have excavated nearly 3,000 km of tunnel. Equipment it lists by project geology includes roof drills, ring beam erectors, back-loading cutters for cutter changes in unstable ground, probe drills, methane detectors and a data acquisition system recording penetration rate, thrust pressure, cutterhead speed and gripper pressure. [4]
Editorial calculation: 14 to 20 in is about 356 to 508 mm. Ask each supplier for disc cutter diameter, gripper pressure and the rock-support equipment fitted behind the cutterhead.
05
Each row follows FHWA's description of a TBM's main body and trailing system; Herrenknecht adds the air-cushion face support used on its Mixshields.
| System | Role | Fix in the order |
|---|---|---|
| Cutterhead and cutters | Excavate the face; discs or picks. [1] | Cutter type, spacing, speed, torque. |
| Grippers or shield | React thrust or support ground. [1] | Type for the ground. |
| Thrust cylinders | Push the machine. [1] | Total thrust. |
| Face support | EPB chamber and screw, or slurry or air cushion. [1] [3] | Support method and pressure. |
| Spoil removal | Conveyor, screw or slurry circuit. [1] | Capacity; separation plant. |
| Segment erector and lining | Builds the lining in the tail. [1] | Segment system. |
| Back-up train | Logistics, ventilation, power. [1] | Length and functions. |
06
Published values here are limited to Herrenknecht's diameter ranges, FHWA's statement that “actual utilization typically runs in the range of 50%” and its note that a fully equipped TBM can occupy over 1,000 ft of tunnel [1]; thrust, torque, power and curve radius must come from the supplier's design for your tunnel.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Diameter (meters) | Examples: EPB 1.7–16 m; Mixshield 4–19 m. [2] [3] | Bore diameter. |
| Maximum Thrust (kN) | Drives penetration. [1] | Installed thrust. |
| Cutterhead Torque (kNm) | Drives penetration. [1] | Nominal and breakout torque. |
| Advance Rate (meters per hour) | Penetration × utilization; FHWA: “actual utilization typically runs in the range of 50%”. [1] | Predicted rate in your ground. |
| Total Installed Power (kW) | Machine and back-up. | Power and supply. |
| Operating Temperature (°C) | Tunnel conditions. | Ventilation and cooling. |
| Cutterhead Speed (rpm) | Affects penetration. [1] | Speed range. |
| Cutterhead Power (kW) | Main drive. | Power. |
| Machine Weight (t) | Shafts and transport. | Weights and heaviest piece. |
| Machine Length (m) | Back-up can exceed 1,000 ft. [1] | Length with back-up. |
| Minimum Curve Radius (m) | Alignment. | Radius. |
| Cutterhead Drive Type | Electric or hydraulic. | Drive type. |
| Shield Type | Gripper, single, double, EPB, slurry. [1] | Type. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Ground: [grading; fines %; plasticity; rock strength; abrasivity] Water: [pressure; permeability] Tunnel: [diameter; length; curves; gradient] Lining: [segments; thickness] Limits: [settlement; structures above] Logistics: [shafts; spoil; power] Programme: [start; target advance]
3 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Lists a tunnel boring machine in its equipment range.
Product scope checked 2026-10-11
Automation equipment trader listing slurry and earth pressure balance tunnel boring machines.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
FHWA says slurry machines become questionable above 20% fines and EPB machines may be unfavourable below 10% fines; mixed ground may need a dual-mode machine. [1]
Penetration rate times actual cutting time; FHWA notes "actual utilization typically runs in the range of 50%". [1]
Herrenknecht lists EPB shields of 1.7–16 m and Mixshields of 4–19 m. [2] [3]
The Robbins Company builds Main Beam TBMs from 3 to 15 m in diameter with 14–20 in disc cutters, for competent to slightly fractured rock. [4]
Sources checked 2026-10-12. The FHWA manual is US government engineering guidance; Herrenknecht and The Robbins Company are TBM makers describing their own machine families. Diameters, pressures and cutter sizes are those makers' examples.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
Compare manufacturer profiles with relevant product and process capability.