The Changuinola Hydroelectric Plant, located in the Bocas del Toro province in Panama, includes a 4,1 km long pressure headrace tunnel (HRC) and a 450 m long surge Adit tunnel (SA). The consortium COBRA INFRAESTRUCTURAS HIDRÁULICAS e HISPANO SUECA DE INGENIERIA was hired to execute a new reinforced concrete lining in segments of both tunnels. FHECOR was trusted by the consortium to carry out the structural analysis and design of the new lining. The existing horse-shoe cross-section has been optimized by rounding its corners, thus reducing the forces acting on the structure. The execution of the lining works has used formwork travelers specially devised to fit the dimensions of the tunnels as shown in the pictures. FHECOR has also provided technical assistance services during the execution of the civil works.