The North/South Line is 9.7 km long. The line has eight stations separated by an average of 1.2 km. The length of the underground section is 7.1 km and includes a bored tunnel 3.1 km long. The line runs from the aboveground Buikslotermeerplein station in Amsterdam North via a semi-sunken route to the Johan van Hasseltweg station and onwards in an immersed tunnel below the river IJ to Amsterdam Central Station. Via three caisson elements on the square in front of Central Station and a bored tunnel, the route runs on via Damrak to the Europaplein station. The section of the route in the bored tunnel includes three very deep stations: Rokin, Vijzelgracht and Ceintuurbaan. The final section of the route runs above ground along the central reservation of the A10 Amsterdam ring road and ends at Zuid station.
This project regularly confronts all stakeholders with challenges, especially because of matters like:
- historic and vulnerable surroundings
- ambitious task with a relatively tight budget
- complex official and administrative setting
- complicated engineering
- innovative and pioneering techniques
- high risk profile
Involvement of Witteveen+Bos
At various levels Witteveen+Bos is playing a role in the construction of the North/South Line. Since 1994 we have been involved in the project as the main contractor and lead member of the Adviesbureau Noord/Zuidlijn consultancy. For the City of Amsterdam (North/South Line Office) we are providing engineering and consultancy services for the line.
Activities of Adviesbureau Noord/Zuidlijn include:
- project and process management
- management of the surroundings
- advice on calls for tenders and contract establishment
- management of licences
- risk management and safety
- on-site management and supervision
- GIS monitoring of adjacent buildings
The North/South Line has been divided into several route sections and building contracts to facilitate the controllability of the project and the contracting of companies to perform the work. Witteveen+Bos holds overall responsibility as the main contractor for all consultancy and engineering services provided by Adviesbureau Noord/Zuidlijn. Within the consultancy the various building contracts have been assigned to the member firms. Engineering firm Ingenieurs Bureau Amsterdam has been given tasks that include the aboveground parts of the route in the north and south of Amsterdam and configuration of the ground level along the entire route. Royal Haskoning teams are working around Amsterdam Central Station and the Rokin and Europaplein stations. DB International provided the design of the rail system, train safety system and the energy supply. Witteveen+Bos is working on all other parts of the project, for instance:
- bored tunnels
- mitigating measures
- monitoring system
- noise and vibration study
- building site safety and user-friendliness of the line
- immersed tunnel in the IJ river and the Sixhaven graving dock
- the Vijzelgracht and Ceintuurbaan stations
The City of Amsterdam has concluded contracts with the contractors performing the work. Adviesbureau Noord/Zuidlijn is acting as a contracting consultant. Back in the 1990s it was common practice to segregate responsibilities for the design and for the construction of infrastructural works. The client stated exactly what had to be built and specified the work in detailed construction contracts and design specifications. It was decided to call for tenders for the carcass of the North/South Line under RAW contracts (intended to rationalise civil engineering projects) due to the complex surroundings, the nature of the work and the tight constraints. Design & Construct contracts and Engineering & Construct contracts emerged later. An E&C contract was awarded for the bored tunnel. The North/South Line Office called for tenders for the transport engineering and finishing of the metro line under a D&C contract.
The calls for tenders got underway in 2000 on completion of the designs and construction contracts for the carcass. Adviesbureau Noord/Zuidlijn oversaw the calls for tenders for the construction contracts. Partly because of the severely overheating construction market at that time, it was necessary to conduct several rounds to agree good arrangements between the city and the contractors. During negotiations between the contractors and the city it was decided to amend a number of the original RAW contracts. This different way of establishing contracts shifted more risks on to the client and necessitated more frequent scope alterations on account of unforeseen circumstances.
Witteveen+Bos/Adviesbureau Noord/Zuidlijn is not performing any of the construction work. That part of the project is being carried out by the contractors engaged by the City of Amsterdam. While the work is in progress, however, Adviesbureau Noord/Zuidlijn is overseeing its performance, submitting engineering advice and providing the detailed engineering for the carcass. Between 2003 and 2007, Adviesbureau Noord/Zuidlijn was responsible for managing contracts and supervising construction. Today these tasks are being performed by the North/South Line Office of the City of Amsterdam. A large number of employees of Adviesbureau Noord/Zuidlijn have been deployed for these tasks. Their deployment while work is in progress assures the availability of the considerable specialised knowledge needed of the complicated designs and its effective use during the work.
Political rethink in 2009
Two cases of subsidence during construction of the Vijzelgracht station and the conclusion that the project faced significant financial setbacks plus a considerable overrun of the schedule prompted a political review. The Amsterdam city council held a public inquiry into the decision-making on the North/South Line. The executive called for the advice of an independent committee of inquiry chaired by former cabinet minister Cees Veerman on the way forward, scope and method of completing the North/South Line. In response to the outcomes of the inquiry, the Amsterdam City Council decided on 1 July 2009 to press ahead and finish the North/South Line. This decision reflected the recommendations made by the Veerman Committee.
Behind the scenes Witteveen+Bos and Adviesbureau Noord/Zuidlijn cooperated intensively in investigating the facts of the case for the city council’s inquiry and the work of the Veerman Committee. At the request of the North/South Line office, Witteveen+Bos/ Adviesbureau Noord/Zuidlijn studied dossiers to answer numerous questions received from the committee of inquiry. We also cooperated in the committee’s closed hearings.