Forming a key part of the strategic roads master plan, aimed at bringing an end to the bottleneck at one of Bahrain’s main arterial roads, the Sheikh Isa Bin Salman Highway (SIBS), the Mina Salman Interchange is made up of two key components, a flyover and a dual 3-lane carriageway underpass.
The complex nature of the project has seen over 700 tonnes of formwork and shoring used to create the flyover, large underpass slab and specialist structures to keep traffic flowing. Working closely with contractor Afcons, RMD Kwikform engineers were involved in supporting the whole project, from foundations to the technical delivery of the super elevation for the flyover.
Keeping traffic moving
Tasked with keeping the traffic moving during the different construction phases of the interchange, Afcons and RMD Kwikform engineers created a solution for a 24m span traffic opening on both sides of the project. Forming a crash deck style tunnel structure to protect traffic underneath the flyover works, each opening had to accommodate the full height of heavy goods vehicles, whilst taking up a very restricted footprint.
This was achieved using a combination of heavy-duty Megashor legs and Superslim Soldiers, to create a strong rigid support structure some 6.137m tall. This in-turn supported special steel beams that spanned the complete opening.
With base plates used to secure the Superslim Soldiers and Megashor legs, to cast-in-situ concrete pads at either side of the rerouted highway, the overall footprint of the solution was kept to a minimum.
In addition, thanks to the use of standard components, including movable jacks, there was no need for any special equipment to be designed and fabricated, leading to an overall reduction in the predicted cost of traffic flow management.
From foundation to flyover
Tasked with carrying traffic from SIBS Highway to Al Fatih Highway, the 265.5m long flyover, with a maximum span of 47m, comprises a seven span cast-in-situ box girder deck. Curved with a cross fall of 5.5 degrees the flyover construction was very complicated, involving the design of specialist items to enable the right level of support to be achieved.
Commenting on the flyover, regional manager for RMD Kwikform Bahrain, Shekhar Sawant said: “There were a number of challenges for this part of the construction. We first had to provide formwork and shoring solutions to support the cast in-situ piers and up to six metres high wall abutments. We then had to develop a shoring design that could support the construction of the main deck, taking into account the curved nature of the flyover and the 5.5 degree cross fall.
“We combined our Rapidshor shoring with specially designed and fabricated connectors to make sure we achieved the radius and super elevation required. At the same time as work was being completed on the flyover we were also using Rapidshor shoring to cast the main slab for the underpass.”
At 1.5m thick, the slab for the underpass measured 34.6m wide and 87m long. Cast after RMD Kwikform’s Superslim and GTX Beam wall formwork had been used to complete the 1200m retaining walls, the slab was constructed in a number of phases. For each section, 80kN Rapidshor shoring, with steel Superslim Soldier primary and timber GTX Beam secondary beams were used to support the underpass, which reached up to 9.1m high.
Shekhar, continues: “In addition to the supply of equipment and engineering design resources to the Afcons team, for this project, we also provided onsite technicians to support the safe erection and dismantling of the equipment. By having our staff on the ground, we were able to support the workforce and manage the flow of some 700 tonnes of equipment in and out of the site. This all made for a much more efficient, fast-track programme delivery.”
Now completed, the Mina Salman Interchange is having a positive impact on traffic flow in the area, reducing travel times dramatically for the residents and visitors to Bahrain.