The complex structure known as the Isa Gate Flyover has been constructed for the Ministry of Works, using the combination of specialist launcher system, supported by Megashor Towers.
Capable of lifting and moving the individually formed precast sections, each weighing up to 190 tonnes, the launcher system is configured to span three piers at any one time. Due to the sheer weight of the precast sections and the very complex camber, in order to ensure the safe erection of the flyover, Megashor Towers were needed to support both the weight of the launcher system at each pier point and the additional weight of the precast sections.
Put into place in a series of three sections at any one time, the precast sections are initially lifted horizontally by the launcher, before being moved vertically to meet the previously secured sections. Once all three sections are in place, they are secured and glued together. In preparation for each of these sequence lifts, RMD Kwikform engineers operating from its Bahrain office, worked with engineers from contractor Nass Contracting to determine the exact forces and moments that would be potentially placed on the Megashor support towers by each precast section.
Armed with these figures and the general site knowledge gained from working with Nass Contracting since the start of the projects, RMD Kwikform engineers provided Nass Contracting site staff with the technical information and drawings required for the erection of each of the Megashor systems.
Erected around the three piers to support the launcher, the tower systems are each made up of Megashor legs ranging in size from 0.5-2.7 metres. Interlaced with Superslim Soldiers for rigidity, the individual towers are connected together to form a rigid structure capable of supporting up to three precast sections. Megashor jacks are used at the base and the top of each tower to vary the height to accurately support two large primary steel beams and a secondary steel beam, mounted onto the top of the Megashor structure. In order to then meet the tight cm tolerances required for the project to support the precast sections, two hydraulic jacks are mounted onto the secondary steel beam, allowing the whole system to be altered to meet the camber of the flyover.
733 individual precast sections are required to be supported and joined together to complete the 1.8km structure. During their time on site, RMD Kwikform engineers clocked up over 400 hours of engineering support for Nass Contracting.
With over 300 tonnes of Megashor, Superslim Soldiers and Kwikstage used on the site, the scale and complexity of the project is under the watchful eye of Nass Contracting Contracts Manager, Ivan Pieterson. Commenting on the project and working with RMD Kwikform, Ivan said:
To say the challenges on this project are complex is an understatement. We are dealing with the creation of the largest single flyover project in the country to date, using a method of construction that is completely new to Bahrain. The curvature of the structure itself is very eye catching and therefore each precast section is unique. Couple this with the nature of the path that needs to be travelled, which also includes constructing the flyover, over and next to live traffic in different sections, and you have a very interesting programme to manage.
Safety and programme management were therefore a major priority for the project. Having worked with RMD Kwikform before, Nass Contracting has developed a very strong partnership approach to the challenges we face
on major projects of this nature. Our engineers work with RMD Kwikform engineers to deliver some very technically challenging solutions. For this project in particular, we are relying on the support of RMD Kwikform throughout the lifespan of its construction. In this time they will be ensuring we have the right levels of kit onsite and also providing us with timely plans, as and when we move from section to section.
I place a very high value on companies like RMD Kwikform that take a customer focused approach, as you feel you are all in it together and will battle through the challenges by pooling resources and ideas. We challenge RMD Kwikform, they come up with solutions, we continue to challenge and ultimately we together develop an approach that is both workable, affordable and most importantly, safe.
With pre-project planning commencing at the start of May 2010, the project construction phase started in June 2010 with the 1.8km flyover completed 24 days early in April 2011.
Talking about the project and input from RMD Kwikform, Shekhar Sawant, Bahrain Technical Manager said:
What is interesting about this project is that we are involved in supporting the countries first precast bridge structure. We are well known in the region for our involvement in cast in-situ structures, but what this project shows is that RMD Kwikform expertise can be used to support a whole variety of projects.
In providing Nass Contracting with a full support service, we have a great opportunity to show them just how versatile our product range is and how it can be used to overcome a whole range of challenges. Putting the hundreds of hours of engineering support to one side, we have also helped Nass Contracting with more practical support onsite. As part of RMD Kwikform’s duty of care to Nass Contracting, before and during the continuation of the project, we have assisted with site erection and equipment safety training. Our specialists have also visited site to check that the tower systems had been erected to plan, adding that extra layer of support and safety.
I think what really makes the whole process interesting, is being able to see the flyover take shape and having those great moments when you see the Megashor equipment in-situ, overcoming a particularly difficult challenge.