Tape Extensometer


The RST Tape Extensometer is a portable device, designed to measure the relative distance between reference anchors fixed to the excavation or structure.


Add to Quote

Product Features

  • Rugged, simple design
  • Rapid one man operation
  • High accuracy and reliability
  • Applicable in any orientation
  • Water/dust proof carrying case


The RST Tape Extensometer is a portable device, designed to measure the relative distance between reference anchors fixed to the excavation or structure.

The instrument consists of a precision punched steel tape incorporating a repeatable tensioning system and dial gauge readout. To obtain a reading, the swivel hook, on the fixed end of the extensometer, is connected to the stainless steel eye on the anchor. The tape is unwound, allowing the tape swivel hook to be attached to the opposing anchor eye. Coarse tension adjustment is accomplished by positioning the pin of the extensometer in one of the precision punched tape holes. Fine tension adjustment is by rotating a knurled sleeve until two index marks align. A precision dial gauge measures this fine adjustment, with the tape held under a consistent repeatable spring force. The instrument is then read by noting the tape position, and subtracting the dial gauge reading.

For maximum accuracy, we recommend that one instrument be dedicated to each project, a calibration frame be regularly used to check stability and determine a temperature correlation, establish new base readings if the tape is changed, and the instrument temperature be allowed to stabilize prior to use.


Range 10, 15, 20, 30 m (30, 50, 100 ft.)
Dial Indicator Resolution 0.01 mm
Repeatability ± 0.25 mm (±0.01 in.)
Weight with 20 m Tape 2.2 kg (5.0 lb.)

Tape Extensometers are commonly used for:

  • Mine roof sag.
  • Measurement of tunnel convergence.
  • Deformation of excavations.
  • Surface measurements for slope stability.
  • Monitoring and control of NATM (New Austrian Tunnelling Method) construction.

View illustrations on how Tape Extensometers are used for tunnel monitoring.

Tape Extensometer Ordering Info

10 m Tape Extensometer with case EXTE0010
15 m Tape Extensometer with case EXTE0015
20 m Tape Extensometer with case EXTE0020
30 m Tape Extensometer with case EXTE0030
30 ft. Tape Extensometer with case EXTE0030F
50 ft. Tape Extensometer with case EXTE0050F
100 ft. Tape Extensometer with case EXTE00100F
Anchor point, groutable rebar type EXTE1000
Optional spare 10 m tape EXTES0010
Optional spare 15 m tape EXTES0015
Optional spare 20 m tape EXTES0020
Optional spare 30 m tape EXTES0030
Optional spare 30 ft. tape EXTES0030F
Optional spare 50 ft. tape EXTES0050F
Optional spare 100 ft. tape EXTES00100F
Optional calibration frame EXTE2000


Optional Equipment

Replacement tapes.
Groutable anchors.
Zero stability reference frame.

File Name

Tape Extensometer

Resource Type

Language Version Download
English EXB0001K
Portuguese EXB0050A
Spanish EXB0034B

File Name

Tape Extensometer Instruction Manual

Resource Type

Language Version Download
English EXM0007H

Speak with an Expert

I’m very happy with the quality of the instrumentation and technical support from RST, as always. They worked with us from the initial stages of the project to ensure that we were fully prepared and equipped to use the RSTAR network for the first time. They delivered everything within the tight project time frame to ensure that there were no delays on site, and the submersible tilt meters looked like new even after over twelve months of being submerged in Thames water!
-Richard Lipscombe, BEng (Hons), Director & Principle Consultant - RL Geotechnical Ltd