Modifying and renovating the 75 year old Maastunnel to meet with modern standards

Abstract

The Maastunnel in Rotterdam was the first submerged tunnel in The Netherlands, built between 1937 and 1942. It needs to be renovated to comply with the new 2019-requirements of Tunnel Safety. The contract has been awarded by the municipality of Rotterdam. This renovation will be executed by a collaboration of TBI companies in which Mobilis takes responsibility for all the civil concrete activities. The other TBI companies involved are Croonwolter&dros (tunnel technical installations) and Nico de Bont (renovation). The project poses a number of challenges. First it is a construction which is at the end of the designed lifespan after 75 years of service. Secondly the structural integrity is at stake due to deterioration. And thirdly the condition of the tunnel needs to be upgraded to meet the current regulations and to prevent closure. One of the safety issues is the tunnel ventilation in case of a fire. The existing ventilation only acts in transversal direction and was originally intended for fresh air only. In case of a fire this ventilation system has insufficient capacity to remove smoke, causing the tunnel to be filled with smoke clouds. New regulations require a longitudinal ventilation which blows the smoke out of the tunnel at high speed. The ventilation system will be located at the tunnel mouths. Because of the limited height in the tunnel it is impossible to situate the ventilators in the tunnel as it is. The only possibility to obtain extra space is to elevate part of the tunnel roof. The elevated parts need to be built while the tunnel remains operational. During inspection of the tunnel floor and the car deck a severe deterioration of the concrete was found. To prevent closure and to maintain structural integrity the tunnel floor needs to be renovated and the car deck needs to be rebuilt. It will be a difficult undertaking to connect the car deck with the tunnel because of missing reinforcements. The ongoing mission is to reconcile authentic aspects with new requirements.