Abstract: A system is disclosed in which a boring tool is moved through the ground in a region which includes at least one electrically conductive in-ground line. The system includes an arrangement for tracking a specific positional relationship between the boring tool and one or more in-ground lines. The arrangement generates a magnetic field from one of either the boring tool or the line. A particular characteristic of the generated field is detected at the boring tool if the field is generated from the line or is detected at the line if the field is generated from the boring tool. The characteristic varies as a function of the specific positional relationship between the boring tool and the line as the boring tool moves through the ground within the region.