Fabrication and Erection of U-Trough Section Bridges

Abstract The U-trough section structure has been largely used in the last decade for Light Rail Transit and Mass Rapid Transit systems all over the world. Approximately 200 km of U-trough section bridges have been already built or are under construction. The typical deck carries one or two tracks; for single track the deck cross section is a small U around 5 m wide, and for two tracks the deck section is a wide U with around 10 m wide. The usual span length is in the range from 25 to 35 m. This paper reviews the applications and the construction technology for prestressed concrete decks using U-shaped precast segments or full precast span. For large-length viaducts it becomes cost effective to use precasting. The deck segments are cast in long line beds or individual cells and are assembled on site using post-tension. Full spans are cast in beds and pre-/post-tensioned on the precasting yard. This paper presents the different erection methods in terms of technical features for both segmental construction and full-span construction. Elements can be transported at ground level and lifted at deck level or transported at deck level and erected with an overhead launching gantry. In the case of full precast span, the erection could be realized by means of two cranes or special gantry. This paper also discusses the development of construction equipments for single-track deck and the interaction of U-shaped structural design and construction equipments.