Guidance system and method for keeping a tunnel boring machine continuously on a plan line

A guidance system for keeping a tunnel boring machine on a plan line through a plurality of segments making up a tunnel, the system comprising:

• a laser light beam from a laser beam source;
• a front target with horizontal and vertical cross-hairs thereon, said front target mounted near the front of the tunnel boring machine, said laser light beam directed toward and impinging on said front target;
• a rear target with horizontal and vertical cross-hairs thereon, said rear target mounted near the rear of the tunnel boring machine, said laser light beam directed toward and impinging on said rear target;
• a on-board programmable computer installed on the tunnel boring machine for imputing data for establishing the plan line and establishing an actual center line of the position of the tunnel boring machine by imputing periodic data as to horizontal and vertical offset measurements taken from the readings on said front and rear targets for each segment;
• and
• a graphic display generated by said programmable computer of the plan line of the tunnel boring machine and the actual center line of the tunnel boring machine for comparing the two lines for each segment, said graphic display used as a guide in taking corrective action as to repositioning the tunnel boring machine as it advances forward toward a segment to be completed.

A method of keeping a tunnel boring machine on a plan line through a plurality of segments making up a tunnel by using a graphic display generated by a programmable computer installed on the tunnel boring machine and using a laser light beam from a laser beam source and using a front target mounted near the front of the tunnel boring machine and a rear transparent target mounted near the rear of the tunnel boring machine, the steps comprising:

• passing the laser light beam from the laser beam source located to the rear of the tunnel boring machine through the rear transparent target and onto the front target;
• taking offset measurement readings for each segment on the front and rear targets;
• imputing the offset measurement readings for each segment in the computer for establishing an actual center line of the position of the tunnel boring machine;
• and
• generating a graphic display from the computer of an actual center line and a plan line of the tunnel boring machine for comparing the two lines for each segment, said graphic display used as a guide in taking corrective action as to repositioning the tunnel boring machine as it advances forward toward a segment to be completed.

A method of keeping a tunnel boring machine on a plan line through a plurality of segments making up a tunnel by using a graphic display generated by a programmable computer installed on the tunnel boring machine and using a laser light beam from a laser beam source and using a front target with horizontal and vertical cross-hairs mounted near the front of the tunnel boring machine and a rear transparent target with horizontal and vertical cross-hairs mounted near the rear of the tunnel boring machine, the steps comprising:

• passing the laser light beam from the laser beam source located to the rear of the tunnel boring machine through the rear transparent target and onto the front target;
• taking offset measurement readings measured from the horizontal and vertical cross-hairs on the front and rear targets for each segment;
• imputing the offset measurement readings for each segment in the computer for establishing an actual center line of the position of the tunnel boring machine;
• and
• generating graphic displays from the computer of an actual center line and a plan line of the tunnel boring machine for comparing the two lines as to horizontal offset and vertical offset for each segment, said graphic displays used as a guide in taking corrective action as to repositioning the tunnel boring machine as to attitude and slope as it advances forward toward a segment to be completed.