Detailed design of an extradosed bridge and connecting viaduct and ramps for traffic improvement of Colombo, Sri Lanka. The extradosed bridge over the Kelani river has main span 180 m and total length 380 m. The connecting viaduct and ramps include cast-in-situ concrete bridges with typical span 47.5 m and steel box girder bridges with maximum span length 59 m. Piers include concrete columns and steel portal frames.