Microtunneling is defined as a trenchless construction method for installing pipelines.  The North American definition of microtunneling describes a method and does not impose size limitations on that method. The tunnel may be considered a microtunnel if all of the following features apply to construction: 

-the microtunneling boring machine is remote controlled, 

-a laser guidance system is employed, 

-a jacking system is used for thrust, and 

-continuous pressure is provided to the face of the excavation to balance groundwater and earth pressures. 

Standard Guidelines covering planning, design, pipe materials, and construction of microtunneling are most useful when applied to project and contract specific conditions.

This Standard Guideline is a vital reference for owners, engineers, contractors, and construction managers.  It should be tailored specifically to project (geological, material character, spatial constraints, and contractual) conditions by expert review.