Patent ID: 9702094
Date: 2017-07-11
CPC Classifications: E01C,E02D,E21D

Claim:
1. A method of forming a tunnel under a surface, said method comprising the steps of forming at least one access point along the route of the said tunnel, forming at least first and second support bases in at least one direction away from the access point along said route, providing the support bases with guide means thereon, and a plurality of deck structures are advanced along the guide means to be supported by, and span between, the respective guide means to form at least the roof of at least a portion of the tunnel so that at least a portion of the said tunnel is formed outwardly from the said access point along said route wherein excavation work is performed to remove the material from the surface to the top face of the deck structures which have been advanced into position to allow the top face of the said deck structures to be available for the positioning of excavation apparatus thereon to perform further excavation work and/or for vehicles to move along the top face of the said deck structures to transport excavated material, and once the tunnel is formed, material is moved over the top face of the deck structures, to allow reinstatement work to be performed.