Hazard sources (e.g. discharge of industrial sewage)

Distance between the shaft or inspection chamber and the most remote spot to be cleaned

Limitations in the accessibility of the manhole/shaft constructions or inspection chambers (e.g. traffic situation, surrounding structures, etc.)

Limitations in the accessibility of the manhole/shaft constructions or inspection chambers with respect to structural conditions (nominal size, etc.)

Necessity of using vehicles capable of off-road use, property rights, possibility of access via the next shaft or inspection chamber in the flow direction