Doha Metro main station construction 'challenging'
Nine metre-high walls call for innovative thinking by formwork specialists and project engineers
As Doha's new metro takes shape, the importance of formwork within the construction sector has come into focus
As an integral part of the Qatar Rail Development Program (QRDP), the Doha Metro project will consist of four lines with the metro network extending over the Greater Doha area. It will have two major stations: Education City Station and the Msheireb Station.
PERI has been awarded contracts for the formwork on both of those major stations and the project is due for completion in 2019.
While one of the benefits of using formwork is that is can be cast off-site, freeing up space, this is not the case on the Doha Metro project. Miguel Colomer Herrero, senior construction engineer, OHL, part of the JV with Samsung and QBC commissioned to build both of Doha’s metro stations, explains, “Every site is different and has its own challenges. This site obviously requires in situ casting as it would be impossible to move them from a remote location to the site.”
Working on the Education City station, he explains why formwork was the method of choice for this construction: “The walls we have here can only be made with formwork because they are 1.5m wide and extend to an impressive nine metres-plus tall.”
Dimitris Papendreou, PERI sales engineer and responsible for the Doha Main Metro project's formwork adds: “The main challenge here was casting the tremendously high walls in one pour of concrete. Usually walls are cast to between four and six metres in height, and then the remaining height is cast in a separate cycle. In this project however, for a variety of reasons, the walls were cast in one pour.”
Herreo adds: “After extensive study of the project, the JV decided to cast in one pour as the client’s requirements dictated this option. The surface finish has to be exceptionally smooth and this would not have been possible in more than one pour as a seam between the two cycles would have been created. Also, this project is expected to be here for about 120 years, so one pour also ensures durability and the best result for waterproofing.”
Papendreou concludes: “Any other method, such as pre-cast concrete was out of the question, as we also had to consider the finishing. It is also a structural choice and takes the safety of the site and end product into consideration.”
The station is 330m long and 29m wide, while the height of the walls vary between 2.8m to nine metres.