Motorists in North Holland could not have missed it, the Velsertunnel is closed. The tunnel on the A22 under the North Sea Canal is nearly sixty years old and in need of a renovation. On behalf of the contractor consortium Hyacinth, Anton Construction has assembled a 4.5km steel formwork for a concrete barrier, which is adapted for draining rainwater by means of an ingenious construction. In addition Anton Construction mounted stainless steel gutters in the ceiling that need to collect the seepage out of the expansion joint. The spout of the gutters runs ultimately back into the gutter under the barrier. A provision is made along the wall of HDPE pipes that run through the barrier and connect to the stainless steel gutters.