One of these currently taking place involves practising hoisting the reinforcement cages for the foundations, sometimes referred to as abutments. This is where, in August 2021, we will insert two sections of roof for the new Amsterdam Zuid station passenger tunnel – the Brittenpassage – into position and there are four more roof sections to follow. We join Rob Vermeulen, planning engineer at ZuidPlus, on the work site, where he explains all the details and background to the experimental hoisting of the reinforcements.
‘We’re making the abutments by removing railway platform 2 and a railway and metro track for a four-day period, starting at 20.00 on Thursday, 1 April and digging open the foundation piles inserted there’, explains Vermeulen. ‘We will then be carefully lowering the pre-made reinforcement cages for the abutments onto these foundation piles before pouring in concrete. These are the reinforcement cages that we are now practising lifting.’
‘We have built these reinforcement cages on the work site over the last few weeks’, continues Vermeulen. ‘There are four in total. The largest reinforcement cage is 7.5 m wide, 7.5 m long and 1.5 m high. Of course, the others are all 1.5 m in height, but slightly smaller in size.’ This week, a crane has already hoisted the cages into the air – we did the largest and heaviest cage yesterday.
‘This kind of cage is made of iron bars and you can test whether the cage is sufficiently robust to be moved and whether the points where the chains are attached are correctly positioned’, explains Vermeulen. The job went well. ‘Practising the hoisting means that we now know the exact weight of the cage, which is 23 tonnes. We are also now sure that the crane we intend to use can take the weight and it’s clear that the reinforcement is properly put together and will not buckle when the whole thing is moved. It’s important that the cage remains hanging upright during hoisting and does not become skewed because otherwise we won’t be able to get it onto the foundation piles. It’s a careful balancing act.’ Incidentally, the cage was not lifted very far off the ground. ‘That’s not necessary: as long as the cage lifts slightly off the ground and stays straight, we have the information we need.’
Another important test is scheduled for next week. Vermeulen: ‘The crane we have been using for the tests is being replaced by another larger crane. It will be delivered in sections in the week before Easter. The trucks being used for this will need to climb quite a steep slope from Parnassusweg to reach the work site. We plan to do test journeys with specially weighted trucks to see if additional trucks will be needed as support or whether the trucks can manage the slope on their own. So, good preparation is the key to success? ‘That’s exactly it’, agrees Vermeulen, nodding.