he Panama Canal Authority on Dec. 17 formally approved four consortiums to compete to construct the $3.35-billion locks at the heart of the $5.25-billion expansion to the historic waterway. Thirty companies from more than a dozen countries make up the four consortiums now prequalified for the locks work. All successfully responded to a request for qualifications last month. Groups are led by Bechtel International Inc.; ACS Servicios, Comunicaciones y Energía, S.L. of Spain; Bouygues Travaux Publics of France; and Spanish company Sacyr Vallehermoso S.A. The canal authority will issue a request for proposals by year-end.