RoyalHaskoningDHV came to this conclusion, which on Wednesday presented the investigation into the collapse of a grandstand in the Goffert stadium in Nijmegen in October last year. In response to the preliminary conclusions of the engineering firm, the Ministry of the Interior has called on all owners of Dutch stadiums and the responsible municipalities in which they are located to have the capacity of the stands checked. During that check, it must be examined what they can handle and whether adjustments are necessary.
Football stands must be able to carry 500 kilos per square meter in the Netherlands. For stadiums built before 2012, such as that of NEC in Nijmegen, 400 kilograms still apply. During the regional derby last year, Vitesse supporters managed to produce forces of 900 kilos per square meter at NEC, by jumping as high as possible at the same rhythm. The standing stand broke in half.
RoyalHaskoningDHV calculated that the Vitesse supporters’ mass weighed about 350 kilograms per square metre. By recreating the concrete slab of the grandstand, the engineering firm discovered that the load caused by jumping together was at least 2.5 times higher per person than if everyone had remained quietly in place.
‘When we saw the images, it didn’t look like extreme behaviour,’ says lead researcher Erik Middelkoop, who was surprised by the results. ‘You got the feeling that this jumping is happening more often. I find it remarkable that the standard has been exceeded so far. Collapses are usually caused by a construction flaw, but we never realized that the load on intact grandstands can be so much higher than they were designed for.’
No one was therefore aware of these risks, said NEC director Wilco van Schaik during the presentation of the research results on Wednesday. “In a way we are happy that this has now happened without any casualties.”
Reinforcing structures
The findings provide an opportunity for other stadiums to make adjustments before similar accidents happen. For example, by reinforcing structures with steel strips, as happened after the incident in the Goffert Stadium in Nijmegen. Or by adjusting the layout of the stands, so that large groups can no longer jump packed together.
Supporters run the risk of collapse not only in standing stands. ‘The bucket seats used in many stadiums make it very easy to push forward and stand on one seat with two people at the same time,’ says Middelkoop. “High back seats are better.” According to him, bars on the standing stands are only part of the solution. ‘It is very complex, we need to look much more closely at the unique building construction of a stadium.’
Following the incident in the Goffert Stadium, football club Heracles Almelo had an investigation carried out by RoyalHaskoningDHV. The first ring of the grandstand in stadium Erve Asito was built in the same period as De Goffert in Nijmegen. Reinforcements will also be installed in Almelo and until then, adjustments will be made to prevent too many people from standing together.
Middelkoop does not rule out the possibility that the standard for peak load in stadiums will be increased on the basis of his research. This new standard then applies to the construction of new stadiums, unless the increase in the standard is very significant. For example, from 500 to 900 kilos per square meter. Existing stadiums will then also have to make adjustments to their constructions.