Method for widening road, superhighway or railway tunnels, without interrupting the traffic

A construction method for widening road, superhighway or railway tunnels, without interrupting a traffic flow, said method comprising a first stage in which a ground between a theoretical profile of a final widened tunnel and that of an original tunnel, is excavated, in steps, to widen and demolish said original tunnel, a second stage, in which a final lining, consisting of one or more arches comprising a plurality of prefabricated segments, is immediately placed in steps at a maximum distance of 2-3 meters from an excavation face, wherein said second stage comprises:

• transporting said segments to said face;
• applying a delayed setting epoxy resin on two ends of each segment to be placed and on a side of each segment that will come into contact with an arch of lining that has already been erected;
• raising and positioning said segments by a segment placing machine, placing the lowermost segments on each side of the tunnel first and then placing the segments in ascending order until the arch is completed with the placing of a key segment;
• placing a jack in the key segment under pressure to make said segments adhere to each other perfectly and to immediately produce a necessary pre-stressed effect to confine the ground around the widened tunnel, wherein before said first and second stage, the ground between said theoretical profile of said final widened tunnel and that of said original tunnel is reinforced and preconfinement operations are performed around a cavity of said final widened tunnel, wherein said method comprises a third stage, in which a foundation construction is made, appropriate to said final widened tunnel, and wherein during said first and second stages and, during reinforcement of the face and preconfinement of the cavity of said final widened tunnel, a traffic protecting steel shell is placed inside the profile of the original tunnel, above which all of the machinery employed in the execution of the said first two stages and in the, execution of the reinforcement of the face and preconfinement of the cavity of said final widened tunnel is operated and moved.