Jahra Road Development is currently one of the largest elevated road projects in the world, involving the construction of 17.7 km segmental viaducts. This project has many unique characteristics, including the precast yard facilities in Doha area as well as the launching gantries used for segment erection.
Construction method used for the elevated structures is precast, post-tensioned segmental bridge. These segments are manufactured in a precast yard constructed specifically for the Jahra Road project. Located in the Doha area in Kuwait, the precast yard covers a total surface of 150,000 square meters. The facility accommodates large-scale precasting techniques and equipment such as different type of molds, gantry cranes, steel factory, storage area, batching plant, curing chambers and offices dedicated to the production of precast segments.
Employing this system of precast segments has helped enhance the speed of production and has ensured better quality.
Precast Segmental Balanced Cantilever Method of Bridge Construction:
Precast segmental balanced cantilever construction involves a symmetrical erection of segments around a supporting pier. Bridge segments are lifted into position; their match-cast faces are aligned and coated with epoxy before bonding the segments together. Temporary pre-stressing is applied on each segment until its balancing segment is installed. Finally, cantilever tendons are installed and stressed from one segment to its counter-part on the other side of the pier.
When all segments of a new cantilever have been erected and tendons stressed, a closure joint is made at mid-span called a stitch. Afterwards, continuity post-tensioning tendons are installed and stressed in-between the piers for span continuity.
The erection process of bridge segments involves using the launching gantries. These launching gantries were designed specifically for the project and weigh 500 tons each, and are 140 meters in length. The launching gantry is capable of lifting bridge segments that weighs up to 120 tons. Currently, three launching gantries are functional on the project.