Second roof section for Minervapassage under construction

An army of steel fixers from the Nieuw-Zuid Construction Consortium (BCNZ, made up of Mobilis, Boskalis and van Gelder) is currently hard at work connecting thousands of rods of concrete rebar to each other. Over a length of around 100 m, they are building a reinforcement cage for a huge sheet of concrete that will form part of the new roof of the existing passenger tunnel (Minervapassage). The roof section is currently being preconstructed on our work site between the metro tracks, but in the summer of 2024, we will move part of it to the north underneath the most northern metro track (M2, see map). Before that stage is reached, there is plenty of work still to be done. ‘Moving it into position is probably the least complicated part of it all’, laughs Edgar Breedveld, foreman at BCNZ.

When the formwork for the reinforcement of this roof section is ready, the pouring of the concrete will start in early May. Around 400 m³ of concrete will be poured into it. ‘That last piece of the roof section – there between the glass domes – can’t be reached with the concrete pump’, points out Breedveld. ‘That means we’ll have to use hoses attached to the pump to get to it.’ The incoming transport of all the concrete rebar is also being done slightly differently because of the very small construction site: ‘If you lifted it using a normal crane, you’d have to pass right over all the passengers. That’s why we are now using an electric portal crane. It runs across tracks on both sides of the roof section and can lift materials without swinging outwards. That considerably improves safety.’

So, broadly what is planned for this seven-week period? After the most northerly metro track has been removed, the demolition work will start. We will remove part of the existing roof of the Minervapassage (consisting of concrete girders) and lift off the glass roofs. This will be done in phases in order to limit disruption to passengers – the passageway will actually remain open throughout the seven weeks. We will then build a new support pillar in the passageway. This is required because the new roof section is much longer and heavier than the part of the roof it is replacing. In early August 2024, we will move the sheet of concrete around 35 m to the north. ‘Don’t forget that we’re now building the roof section on top of another roof section – that means that it will soon need to be lowered by a further 2 m’, says Breedveld. ‘It’s a step-by-step process. It will properly take around 48 hours.’