Cast asphalt makes platform walkable, waterproof and sufficiently slip-resistant 

The renovated platform above the Westknoop features a cast asphalt finish, as has been customary at Amsterdam Central Station for many years. For this, BAM Infra Civiel called on the expertise of SBO from Andelst. SBO took care of the complete construction of the platform floor, including the waterproofing of the concrete shell to the final top layer in cast asphalt.

SBO has a lot of experience applying poured asphalt, especially on complex projects. "We may be a subsidiary of BAM, but that doesn't mean we have every project in our lap," says SBO's Rody Eikelenboom with a laugh. "Through experiences on previous projects, there was a valuable connection between the work planners. That's how we came to the table for this project."

Unique feature

The job for SBO involved applying a waterproof layer to the newly poured concrete shell of the platform and applying two layers of poured asphalt on top. "The waterproof layer consists of a special roofing material that completely adheres to the concrete substrate," explained Eikelenboom. "This was followed by two layers of poured asphalt totaling 5 inches, which was necessary for the waterproof finish and the expected load. That total build-up results in a sturdy, waterproof and functional floor finish for the travelers." Unlike what you might expect from such a tight floor, Eikelenboom says poured asphalt has the unique property of remaining sufficiently slip-resistant under all conditions. "If the floor is wet, it becomes even slightly more slippery."

Cast asphalt dumpers

Looking back on the execution, surely the biggest challenge was the tight time schedule, according to Eikelenboom. "The work had to be completed quickly because the station was already partially in use. Logistically it was complex, especially because of the use of trucks, lifting equipment and cast asphalt dumpers to bring the cast asphalt to the platforms. In addition, the wheel dumpers were not allowed to be fully loaded because of weight limitations of the platform deck. These were all puzzle pieces that we had to put in place to bring the project to a successful conclusion. And we succeeded. Although it is impossible to match the classic look, with time the floor will take on a similar look to the other platforms. Subsequently, we also constructed platform 6 for BAM Infra Civiel. While that did not fall within project Westknoop and has a different construction structurally, the finish is ultimately identical."