The focus of this Paper is on utilizing cutting-edge technologies and techniques to gather comprehensive data, even in challenging environments. The goal is to achieve accurate and reliable measurements in any ground condition, whether it is soft soil, hard rock, or anywhere in between. A good instrumentation program has the potential to change the way we approach subsurface engineering, making it possible to tackle even the most complex geotechnical challenges with confidence. To start with, the Paper dwells upon the basic purpose of instrumentation and the essential attributes of a good instrumentation system. It explains functionalities of the diverse type of instruments deployed in tunnelling. The designers of the instrumentation program may find the discussion quite useful. Elements of a foolproof instrumentation program have been discussed in detail. The Paper highlights the most crucial but commonly ignored aspect of data analysis and interpretation. What is the use of instrumentation if their data is not utilized? The instrumentation program must be able to analyze the data through an on-line Software and present the results in a form that can enable easy interpretation of the results. Instead of long data tables, the instrumentation results must be presented in graphical form. Today’s IT technology has made it possible, as brought out in this Paper. With this perspective, the way instrumentation is looked upon today needs to be changed. Clearly, there is a need to accord instrumentation the attention that it deserves. Finally, typical instrumentation systems have been presented for varying rock conditions. However, it must also be appreciated that in tunnelling we are dealing with naturally occurring unpredictable ground conditions. Howsoever hard one may try; it will not be possible to standardize instrument schemes for different rock conditions. Instrumentation design has to be an evolving process and will need to be updated depending upon the data received from the instruments as the actual results might reveal unpredicted rock behavior. © 2023, Central Board of Irrigation and Power. All rights reserved.