Instrumentation and monitoring are an essential part of current tunnelling practice. For safe and economical tunnelling in sensitive construction environments a continuous adaptation of excavation and support design is required so that input parameters can be revised when the predictions deviate from measured values.

In addition, systematic monitoring results can provide valuable information pertaining to imminent collapse, thus, making it possible to control the tunnel stability by providing proper countermeasures.
The recommendation focuses on the contribution of monitoring to the successful completion of a tunnelling project, through real time usage of monitoring information as part of the construction process. It should be read in conjunction with the ITA publication Guidelines for Tunnelling Risk Assessment by Eskesen et al. (2004), as this approach can be viewed as one way of mitigating risks involved in tunnel construction.

A special emphasis is given to the use of absolute displacement measurements by geodetic methods for use in tunnelling control. It should be noted that this recommendation does not address the specific aspects related to monitoring of TBM parameters.