Bridges

The Shaikh Khalifa Bin Salman Highway (SKBSH) and Shaikh Isa Bin Salman Highway (SIBSH) are two of the most important arterial roads of the Kingdom of Bahrain. The project for the improvement of the two highways included their junction, known as the Saar Interchange, with a grade separated left turn ramp designed to link the southbound SKBSH onto the eastbound SIBSH. The ramp comprised a 515m long flyover bridge built using the incremental launch method (ILM). The launching path of the bridge followed part of an off-axis circle with a radius of approximately 200m, making it a near half semicircle in plan. The twin-cell box girder was arranged in 14 spans and sub-divided into three parts insitu after launching for its expansion joints. Top and bottom flange non-concentric prestressing tendons were used, enabling the removal of traditional second stage prestressing and simplifying construction. The design was carried out according to AASHTO LRFD, Bridge Design Specifications, 20121. This paper gives an overview of the detailed design and discusses the specific aspects of the construction method employed.