Formidable formwork on the Doha Metro
Doha Metro Education City station is taking form
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.
The project will include connections to town centres and vital commercial and residential areas throughout the city. While in central Doha the metro will be underground, on the outskirts of the city it will mainly be at ground level or elevated.
The use of formwork has become a vital part to the success of the project, with a variety of contractors and companies vying for the opportunity to put their expertise to use.
One such company is Peri, an international manufacturer and provider of formwork and scaffolding systems, with its mother company in Germany.
Doha Metro will have two major stations: Education City Station and the Msheireb Station. A consortium of companies from Spain, South Korea and Qatar won the contract worth $1.4bn to build these two iconic stations.
Samsung C&T, Obrascon Huarte Lain (OHL), and Qatar Building Company (QBC) won the concession, of which $500mn corresponds to civil engineering and the rest to electromechanical and architectural work.
Msheireb Station is the most important station and will be located in the heart of downtown Doha, which is currently undergoing an urban restoration project. The Education City station, which is located on the outskirts of Doha and is planned to connect with a regional railway, aims to be a centre for educational excellence in the Gulf region.
Peri has been awarded contracts for the formwork on both stations and the project is due for completion in 2019.
Miguel Colomer Herrero, senior construction engineer, OHL, explains the company's involvement: “The project we are working on is the construction of the metro stations, using formwork specifically for the construction of walls and slabs,” he says.
The station is 330m long and 29m wide, while the height of the walls vary between 2.8m to a lofty nine metres. “We are using a standardised Vario system for construction of the walls,” explains Dimitris Papandreou, Peri sales engineer and responsible for the Doha Main Metro project.
His responsibilities include preparing offers and quotations to the JV, as well as doing presentations to both Qatar Rail and the JV and coordinating with the consortium’s design team to prepare the necessary drawings. These included the construction of the walls and columns and the slab, “as well as producing a mock-up for Qatar Rail, to ensure that everything is working well”, he elaborates.
The dimensions of the walls necessitated the use of formwork because of their immense size. Herrero explains, “The walls we have here can only be made with formwork because they are 1.5m wide and extend to an impressive nine metres tall. Any other method, such as pre-cast concrete was out of the question, as we also had to consider the finishing. In addition, it is a structural choice and takes the safety of the site and end product into consideration.”
Papandreou 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.”
Herrero continues, “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.”
Papandreou explains further, “Special conditions are required in terms of the waterproofing of walls and columns in the stations, as well as the slabs, which range between two and three metres in thickness.” He adds, “Our next challenge is around the corner as we prepare to cast our first slab that will be two metres thick.”
While one of the cited 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 and Herrero adds, “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.”
Papandreou adds, “While there is formwork for every application, we took the different conditions into consideration, such as height and thickness; as well as the cycles, namely how many times will the formwork be reused in order to complete the structure. We also considered the most time and cost-effective options for the project.”
The result was an original approach, whereby the formwork was constructed in such a way as to be adapted to the varying heights of the walls. Each panels is made in two different-sized sections, bolted together.
Through a number of permutations the sections can be dismantled and re-assembled forming a variety of different heights as the tunnel changes dimension. Of the $1.4bn total budget for both stations, the formwork cost is $400mn for the Education City station.
Given the inevitable convergence of projects as they heat up to meet the World Cup 2022 deadline, the potential
of material shortages come starkly into focus, more so that cement is one of the commodities most needed in the construction sector generally.
Herrero is short in his response to being asked if this is a worry, given that formwork is about concrete: “It’s one of our main concerns,” he says.
“It’s not only the metro but many other projects on the go in Doha that are going to require materials – not only concrete, but also grabbo. We are worried about this eventuality.” He says that planning in advance and placing orders up front is a possible way to avert the shortage likelihood, adding, “To schedule the order as soon as possible is the one strategy.
Some contractors are actually purchasing materials up front and storing them, while we have put in our purchase requests ahead of requirement; we have ‘booked’ materials. Although here in Qatar, that doesn’t mean that we will have the materials on time,” he adds worriedly.
Access to skilled manpower and logistical issue continue to be challenging on the projects and Herrero explains that ongoing training is part of the projects generally, as is the issue around visas and accommodation.
“You have to cater for and work around the lengthy process of visa applications and accommodation regulations. But through planning properly a project will be minimally impacted on,” he adds optimistically.
“Presently we are so busy with a number of recently awarded mega-projects, that we are finding it challenging to follow up on the tender project,” Papandreou says. As Peri is a global company, he says that by uniting forces internationally with Germany and locally in Qatar and Dubai, manpower is being allocated to address this issue.
“While it is not in our scope –what with us being concrete works – nevertheless, MEP continues to be a hiccup in the tender process, when I speak to contractors, who are frequently voicing concern about it. According them, there is a shortage of MEP companies in Qatar.
“There is also a serious shortage of skilled people in the country, because there is not enough time to train people up; they need to come with the required skills and expertise,” he adds.
That said, Papandreou is excited about the prospects ahead: “When you have this type of project, while it has its challenges, it brings new life and energy to the people working on it.
“These are going to be the most technologically advanced stations in the Middle East, with extensive R&D into what materials are best suited for décor both in and outside” – and Peri is going to be able to lay claim to producing some of the most formidable formwork to making it a reality.