Abstract: A method for generating a new or corrected horizontal underground bore path from a point below ground for use with a horizontal boring machine. In the preferred embodiment, orientation and depth measurements for a boring tool located below ground are recorded. The current position of the boring tool is determined using a previously determined position, measured orientation of the boring tool, and calculating for pipe bend characteristics. Previous measurements and determined positions are recorded to provide a map of the bore. A new path is calculated using the current position as a starting point and through predetermined critical points for the bore. Instructions for drilling the next segment of the bore are made available to an operator or to a control system for a boring machine.