Patent ID: 7669272

Claim:
A process for building bridges, comprising the steps of: providing approximately 3 span lengths of roadbed at bridge level constructed by other means; providing span support structures arrayed at one span intervals along bridge route; placing or assembling approximately 3 additional spans atop said roadbed also atop a low friction transporting means interspersed between the bridge roadbed and said additional spans; providing motive means for moving said additional spans to an end of the roadbed; attaching one or more horizontal girders atop and extending longitudinally along the transported spans; providing lifting means lifting front and rear transported spans into suspension supported at the roadbed by a central span thereby placing attached transported spans and lower web of said girders into compression, also placing upper web of the girders into tension; providing said motive means for further moving the assembled girders and spans to one span length beyond said end of the roadbed putting the far end suspended span and girders in cantilever; providing support means between the girder ends in cantilever and said span support structures one span length beyond the bridge roadbed whereby compression and tension are released from girder and span assemblage; providing lowering means for lowering the cantilever span from girders onto the support structures and into level alignment with the bridge roadbed; and repeating the process as often as necessary while the extended spans are approximately level.