10,000 tons a day: renovating a major runway at Brussels Airport

To guarantee safe landings and take-offs, Runway 25 at Brussels Airport has been renovated completely. To limit the closure and the impact of the works, the specialists of Willemen Infra and Top-Off were on the job 24/7 and with the help of Topcon succeeded within the limited time frame.

Runway 25 is 3.3 kilometers long and 45 meters wide. It was last renovated in 1996. Over almost the entire surface of the runway, the top layers of asphalt had to be milled and replaced. The runway’s lighting system, including cabling, also had to be replaced, as well as the drainage system.

“We renovated the runway, including its shoulders and crossings,” said John Vastmans, CEO at Top-Off. “We placed two new layers of asphalt on it, which amounted to 222,000 square meters and about 60,000 tons.  The work had to be 90% done in just five days. That is to say: we milled at a rate of more than 10,000 tons a day.”

Both while cutting the existing asphalt layer and rolling out the new surface, time was of the essence.


“90% of the work had to be completed within five days! We were milling at a rate of more than 10,000 tons a day.”

John Vastmans, CEO, Top-Off

How to deal with a lot of traffic on-site

Philippe Grevendonck, Key Account & Project Development Manager at Topcon Positioning Group, commented:. “The existing tar layer had to be removed first. This was done following the traditional 2D method. After removing the tar layer, we started to mill according to the 3D model. Thanks to this 3D milled surface, Willemen Infra were able to place their asphalt at a constant thickness.”

Which technology did they use? “We worked with an optical system to mill the shoulders to design. On the runway itself, we used 3D millimeter GPS,” says John Vastmans. “We milled the surface with two machines leaving a pass of 3m80 in between. This pass was milled with the 3m80 milling machine, without 3D guidance installed. Due to the two passes, the 3m80 machine followed the 3D milled design left and right with its skis. This enabled the 3m80 milling machine to actually mill in 3D without having a system physically installed.”

“The biggest challenge on this project was the ongoing transportation of materials without stalling,” Philippe Grevendonck explains. “There was a point where there were 20 excavators, 30 dump trucks, 20 trailers and five milling machines all there at the same time… An immense amount of traffic. We were able to tackle these obstacles by using millimeter GPS.”

“Topcon's technology allowed us to keep working to millimeter accuracy over a long distance. That used to be much more difficult.”

Jan Eikenaar, site manager, Top-Off

A much faster way to work

“There were always five lasers set up on the project,” Grevendonck elaborates. “All machines could select a laser of choice within reach. One laser could give guidance to multiple milling machines simultaneously. So, we actually tackled our biggest challenge with millimeter GPS technology." 

“It went very well,” says Jan Eikenaar, site manager for Top-Off. “We finished ahead of schedule. That’s always a favourable position to be in. The customer is s very satisfied. Our work was grade-checked, and we remained well within the error margin.”

Until now, they had only worked this way on smaller projects. “This time it was such a gigantic project that we brought in extra machines and extra people, because we’d been working in 24 hour shifts. Topcon supported us very well with their technology, as well as their people.”

Eikenaar enthusiastically adds: “Topcon’s technology allows us to mill to 3D design quickly and accurately, without struggling with the ongoing transport movements. That used to be a much more difficult task. It’s much faster to work this way. I am convinced that it’s cheaper, and the error margins are unprecedentedly low.”

As well as improving the use of the runway for pilots and passengers alike, the successful renovation also means the runway’s lifetime has been prolonged by 15 years.

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