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Accurately immersing tunnel elements in Irak

As part of the Grand Faw Master Plan infrastructure project in Iraq, we placed ten tunnel sections in the Khor Al Zubair River. Thanks to the positioning system designed by subsidiary Dibec, this was done with millimetre accuracy. Dimensions and Monitoring Manager Clemens Tierie explains more.

Simple principle

Ten tunnel sections, each 125 metres long and weighing 46,000 tonnes. With daytime temperatures regularly reaching 50 degrees, the tidal action from the Persian Gulf and geopolitical tensions in the region, it is no easy task immersing all those sections carefully and in exactly the right place. Dibec's positioning system was essential in this, Clemens knows. ‘But in principle,’ he says, ‘it’s a very simple system. It consists of a combination of existing systems, to which we have added a highprecision calculation of measurement values. During immersion, we use various sensors from two points to measure all kinds of properties of a tunnel section, such as its tilt and position. In fact, with the system we indicate the difference between where a tunnel section is located and where it should go. Then you know exactly during the immersion: it still has to go so far to the north, so far to the east and so far down, and then it’s in the right place.’

The art of knowing for sure

The positioning is done using measuring equipment in two 'towers', which are placed on a tunnel section during mimmersion. This makes it possible to display the position on a dashboard along the x, y and z axes. The immersion mcommanders can use this to navigate the sections to their final position under water. ‘We monitor that process using precise measurements’, says Clemens. ‘After all, you have to know exactly what you’re doing down to the mmillimetre. That's the art. During immersion, the sections must fit together precisely and in a controlled manner, but without colliding with each other. This would cause damage, with potentially major consequences for planning and budget. The last tunnel section was the most nerve-racking. At that moment there was only one spot left, and that last shoebox of 125 metres had to be fitted in exactly. Fortunately, everything went well with all ten sections.’

The New Silk Road

Al Faw Port is located in the far southeast of Iraq, on the Persian Gulf. Within the Grand Faw Master Plan, it is set to become the largest port in the Middle East. This includes a land connection that links this growth area via Baghdad to Turkey and the rest of Europe. This creates the New Silk Road: a good alternative to the Suez Canal, located more than 1,500 kilometres to the west. Ballast Nedam contributed to this enormous infrastructure project by immersing ten tunnel elements. Through the newly built tunnel, traffic crosses the Khor Al Zubair River at Al Faw.

Teamwork

As crucial as the system was in this complex project, Clemens emphasises that it was teamwork from start to finish. ‘Indeed, we are the experts when it comes to measurements and positioning. Ballast Nedam is very active in the niche market of immersed tunnels, and we are trusted to make an important contribution. And we live up to that. But in doing so we rely on a whole network of professionals, from suppliers and fellow specialists to theoretical modellers and the people who are out in the field with the measuring equipment in their hands. We really do it together.’

Flawless every day

Clemens was involved in the project from the summer of 2023, and was present on site about five times. But some colleagues were there much longer. ‘They really made sacrifices. When you’re in Iraq for weeks on end, with your family in the Netherlands, that can be quite difficult at times. On the other hand, if you want a predictable job, this isn’t the work for you. In the end, we are extremely proud of what we have achieved here together. Working 60+ hour weeks and 24/7 shifts during the immersion itself. With that constant pressure: one small mistake means big damage. That is a big responsibility for the people on site. Measuring itself is not complicated, but working flawlessly every day is. That’s why it’s amazing to see that, despite that pressure, we end up on the other side of the river, a kilometre away, with an accuracy of 5 millimetres.’

Capability to deliver

How does Clemens look back on the project? ‘With a positive feeling. Perhaps the most pressure was on the preparation. The work had already been taken on when we started, with only about six months to build a working and reliable positioning system from scratch. That demanded a lot from our organisation. We had to figure it all out. For example, it was new to me that it takes two to three months to get all the necessary things to Iraq. But thanks to our good network, it all went well both financially and logistically. This project gave us the opportunity to show what we are capable of: we can deliver what is asked of us, even under time pressure.’
  • Afzinktunnel Basra, Irak

Table on wheels

The time pressure was so great that there was hardly any time to test the positioning system. ‘We literally did that in a parking lot, with a table on wheels as a tunnel section. We lifted it to see if our calculations and the measurements were correct. I think that's what’s great about our company. We get non-standard requests from clients, and we just solve them. Whatever it takes.’

Wind and weather

Now that the tunnel in the Khor Al Zubair is in place and the New Silk Road has been opened up northwards, Clemens and his colleagues are already well into new projects. ‘We were recently involved in sliding a new tunnel into place at Hooipolder and are working on everything related to the A27 project at the Nieuwe Merwedebrug. Another interesting one is a large LNG jetty at the mouth of the Elbe in Brunsbüttel, which rises from the water on a series of concrete mushrooms and poles. When I look at it from a distance and see one of us standing there in wind and weather with his measuring device... Whether it is in the south of Iraq or in the north of Germany, he is responsible for determining where the required piles go into the ground. We do solid and important work, and we are happy to apply our expertise.’

Want to read more?

Are you curious about the project in Iraq, or would you like to know more about immersed tunnels? You can find more information below about tunnels, the project and our areas of expertise.

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    Immersed tunnelling

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