Rules and standards for micro-tunnelling

Careful preparation in terms of planning and formulating invitation for tender documents form an important initial stage if a micro-tunnelling project is to be realised successfully. At the same time such careful preparatory work permits the companies tendering to cost their work optimally. In DIN 18319 "Micro-tunnelling", which is a component of VOB part C, the following points are laid down amongst others:

Details of the site by the client

• Billing units
• Recent grading of soil and rock in terms of their suitability for microtunnelling
• Requirements for the mode of execution, e.g. applicable procedure in the case of variances from the agreed reference axis or in the case of obstacles arising
• Billing

ATV (Technical Waste Water Association) working sheet A 125 "Microtunnelling" is based on DIN 18319 but goes significantly further in its statements. In addition to describing unmanned and manned microtunnelling systems, it lays down requirements in terms of:

• Construction and mechanical devices
• Jacking pipes, jacking pipe connections and shafts
• Preparatory planning
• Execution by the contractor

Further themes are:

• Microtunnelling under the lines of German Railways
• Microtunnelling under federal main roads and motorways
• Microtunnelling under federal canals.

The ATV working sheet as an important set of rules for planning and executing projects is now serving as the foundation for a European set of rules for microtunnelling.