To guarantee safe landings and take-offs, Runway 25 at Brussels Airport is being renovated completely. To limit the closure and the impact of the works, the specialists of Willemen Infra and Top-Off are on the job 24/7. To succeed within the limited time frame, they receive assistance from Topcon.

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

“We are renovating the runway, including its shoulders and crossings,” says John Vastmans, CEO at Top-Off. “We are placing two new layers of asphalt on it. 222,000 square meters, about 60,000 tons. This has to be 90% done within five days. That is to say: we are milling at a rate of more than 10,000 tons a day.”

And so, both while cutting the existing asphalt layer and rolling out the new surface, time is of the essence.

Philippe Grevendonck, Key Account & Project Development Manager at Topcon Positioning, tells us about the process. “The existing tar layer had to be removed first. This has been 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 will be able to place their asphalt at a constant thickness.”

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

“The biggest challenge on this project is the on-going transportation of materials without stalling,” Philippe Grevendonck explains. “There was a phase where there were 20 excavators here, 30 dump trucks, 20 trailers, 5 milling machines at the same time… An immense amount of traffic. We were able to counter these obstacles by using millimeter GPS.”

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

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

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

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

Besides improving the use of the runway for pilots and passengers alike, the successful renovation also means the runway’s lifetime is prolonged by 15 years.