Witteveen+Bos, Royal HaskoningDHV and Ingenieursbureau Amsterdam collaborated on the project in a consortium called Adviesbureau Noord/Zuidlijn. During the design phase, the contract preparations and the supervision of the performance of work, the joint venture made a significant contribution to this technically complex project. A key precondition in the design phase was the requirement to retain the historical character of Amsterdam’s city centre. At the start of the project in 1994, this meant that the underground metro line could only be realised if conventional construction methods were applied in a very creative manner. Existing methods such as bored and immersed tunnel construction and pneumatic sinking of caissons have undergone radical innovation to suit the unique circumstances prevailing in Amsterdam. By developing these innovative methods, the Dutch engineering and construction industry has now gained an even stronger leading position in underground construction, both domestically and internationally.
The North/South Metro Line is a complex project characterised by budget overruns, delays, difficulties in the political decision-making process and problems during construction. These issues sometimes eclipsed the wonderful technical achievements realised during the project. The completion of the line is a good occasion to highlight the feats of engineering that made the North/South Metro Line possible. We conducted retrospective interviews with two founders of Adviesbureau Noord/Zuidlijn: Hans de Wit, managing director of Tunnel Engineering Consultants (TEC) and a project director at Royal HaskoningDHV, and Frank Kaalberg, leader of the Underground Infrastructure PMC and senior consultant at Witteveen+Bos.
The opening of the new metro line represents a crown on the achievements of the Dutch engineering consultancies Witteveen+Bos and RoyalHaskoningDHV. With their expertise and vision, both firms demonstrated their pioneering role in this one-of-a-kind project. Furthermore, unique experiences were gained from the use of highly innovative techniques. As a result, the Netherlands has further strengthened its leading international position in underground construction. The techniques used in the North/South Metro Line have already been applied in other infrastructure projects in the Netherlands and abroad, including the Sluiskil Tunnel in Terneuzen, the Hubertus Tunnel in The Hague, the Baan Tunnel in Rotterdam, the Oosterweel Link in Antwerp, a number of Vietnamese metro lines, and the Crossrail railway in London. The knowledge acquired was shared extensively with colleagues in various committees, and incorporated into a number of new guidelines for underground construction. The ground-breaking design of the North/South Metro Line has not gone unnoticed outside the Netherlands. The project won the prestigious Ground Engineering Award twice: in 2014 for the design of the bored tunnels and the special techniques used for that purpose, and in 2013 for the innovative techniques used in realising the ‘table structure’ and the immersed tunnel below Amsterdam Central Station.
The North/South Metro Line is 9.1 kilometres long, mostly located underground, and has eight stations. The metro tunnel runs directly below the IJ river, Amsterdam Central Station, and the historic city centre. The line connects North and South Amsterdam and is expected to transport approx. 121,000 passengers per day on average. It takes just 16 minutes to travel from the north to the south of the city by metro, half of the former travel time.
Techniques used in the construction of the North/South Metro Line: