Brussels Airport Runway 25 – 3.3km long and 45 metres wide – is being renovated completely; over almost its entire surface, the top layers of asphalt have to be milled and replaced, while the runway’s lighting system (including cabling) as well as the drainage system, need to be restored. 

To limit the closure and the impact of the works, the specialists of Willemen Infra and Top-Off are on the job 24/7 and, with assistance from Topcon, are helping to ensure success within the project’s limited time frame. 

Runway 25 is 3.3 kilometres long and 45 metres 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.

John Vastmans, CEO at Top-Off, said: “We are renovating the runway, including its shoulders and crossings. We are placing two new layers of asphalt on it which is 222,000 square metres, 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.

Dealing with a lot of traffic on-site

Philippe Grevendonck, key account and project development manager at Topcon Positioning, explains the process: “The existing tar layer had to be removed first and 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 consistent thickness.”

Discussing the technology being used, John Vastmans says: “We work with an optical system to mill the shoulders to design. On the runway itself, we are using 3D millimetre GPS.

"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.”

Grevendonck explains further: “The biggest challenge on this project is the ongoing transportation of materials without stalling. There was a phase where there were 20 excavators here, 30 dump trucks, 20 trailers, and five milling machines on site at the same time, which is an immense amount of traffic. We were able to counter these obstacles by using millimetre GPS.”

A much faster way to work

“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 millimetre GPS technology.”

Commenting on the progress off the project, Jan Eikenaar, site manager for Top-Off, says: “It’s going very well, 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, the business had only worked this way on smaller projects. Eikenaar explains: “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.

“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 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 will be prolonged by 15 years.