Abstract: The range of movement by a winning tool of a tunneling machine is controlled to release material from a heading wall to form a tunnel having a desired profile. The tunneling machine carries gyroscope detectors and a detector for a laser beam which is projected along a desired tunnel heading. Such detectors provide electrical signals corresponding to a position change of the tunneling machine. Position transducers, coupled with counters, provide electrical signals corresponding to perpendicular position coordinates of the winning tool with respect to the tunneling machine. Means, including a computer, receive these electrical signals and continuously compute a limit coordinate signal based on a desired tunnel profile provided by a computer program.