ITA’s working groups on mechanized (WG 14) and on conventional tunnelling (WG 19) elaborated

several documents regarding the specific tunnelling methods [1], [2], [8]. In many projects the ground

conditions allow either conventional or mechanized tunnelling methods. Therefore, many Owner’s

organisations have to find an answer on the question which would be the most appropriate tunnelling

method for their project.

Both working groups agreed during the WTC 2010 in Vancouver that recommendations on this topic

shall be a joint work of both working groups. The answer on the question of the most appropriate

tunnelling method depends on many factors for each individual project, not only on the ground

conditions but also on many other factors as discussed herein this report. It also depends significantly

on the knowledge gained during the project development and on other projects in the area. The

complexity of the topic does not allow a simple approach.

The present document intends to highlight the influence of the main project requirements and the

factors affecting the selection of the tunnelling method depending on the different project phases.

This document does not include typical technical data, such as advance rates, penetrations rates

depending on ground conditions, etc. Such aspects shall be treated in a future ITA-Report.

Each project is unique and requires independent project-specific assessment. However, these

recommendations represent guidelines and suggestions for the project development with respect

to the selection of the tunnelling method in general. The recommendations were developed on the

“design – bid – build” procurement model. If other models, such as e.g. the “design – build” are

chosen, the general approach will be the same, but with a different allocation of the responsibilities.

The present report does not treat this topic in detail which shall be analysed in a future document.

Also the list of typical documents is only a first collection of some examples. This list shall be

developed in a next report of ITA.

These recommendations are intended to be used by Owner’s representatives, tunnelling engineers

(Design Engineers and Site Supervision), Contractors and Subcontractors.