In March 2019 it was found out that the Stadsbaan tunnel in Utrecht does not meet the safety requirements. According to these requirements, the concrete in the tunnel must be able to withstand an extremely hot fire for at least two hours, but heat tests showed that this was not the case in some parts of the tunnel.

In order to make the tunnel fireproof, we have applied fire-resistant cladding to the walls that can withstand more than 1200 degrees Celsius. Should a fire break out in an accident, the concrete will remain intact and there will be no cracks or chips that could weaken the tunnel.