Continuous incrementally erecting viaduct construction system

Method for constructing a precast segmental viaduct comprising the steps of:

• constructing a first viaduct pier to support the rear end of a span to be constructed, said viaduct pier having a "Y" shape;
• constructing a second viaduct pier to support a front end of a span to be constructed, said viaduct pier having a "Y" shape;
• mounting first and second vehicle support means on said respective first and second piers for supporting an erection and assembly vehicle;
• providing an elongated erection and assembly vehicle for spanning between at least two viaduct piers and for moving between successive piers, said vehicle having a top deck, an elongated central longitudinal beam having a down facing elongated planar bottom support surface, a pair of elongated trusses secured to and inclined outward from said beam, and a pair of elongated longitudinal planar top support surfaces extending along opposite side edges of said top deck positioning the longitudinal erection and assembly vehicle that passes through said first and second piers, with vertical and horizontal jacks integrated in the vehicle and in its supports;
• mounting said vehicle between said first and second piers;
• blocking the vehicle against the arms of the said first and second pier;
• adjusting, if required, the camber and the torsional rigidity with internal post-tensioning;
• using the swivel crane fixed over the nose of the vehicle to lift up, rotate and place, sequentially, the segments of the span being assembled;
• once the segments are released by the swivel crane, each segment is pushed or pulled to its final position in the span, levelled and adjusted against the previous segment;
• after assembling all segments of one span, the post-tensioning cables are placed and stressed and the span becomes self-supported;
• the vehicle is then lowered and pushed or pulled to the next span, with the nose and the tail assuring the stability of the vehicle that remains always supported by 2 piers.