Herrenknecht TBMs ordered for Malmö

Malmö Citytunnel Group (MCG), the German and Danish contractor consortium that will build two 4.5km long tunnels under the centre of Malmö in southern Sweden, has ordered two Herrenknecht TBMs for delivery in late 2006.

The 9m diameter Herrenknecht TBMs will each be 120m long including the back-up gantry. The first machine is due to be delivered to site in September next year, with the second following a few months later T&TI was told. Members of the public can see assembly of the TBMs in the shaft from special viewing platforms installed for that purpose. Boring is planned to get underway at the turn of 2006 / 2007, with two years allowed for the drives through water bearing limestone.

MCG is made up of Bilfinger Berger, Per Aarsleff and E Pihl & Søn. It was awarded contract "E201 Tunnels and Underground Cavity" in November last year, actually before all the necessary environmental consents had been obtained in order to meet tender validity deadlines. Worth US$330M, contract E201 covers 6km of parallel tunnel of 7.9m id, of which 4.5km will be bored. The scope also includes 13 cross passages, two access shafts and Triangeln underground station; 28m wide, 12m high, 25m below ground it will contain a 250m long platform.

Groundwater flows are expected to be modified extensively by the project. For this reason, the TBMs are favoured as they pose less risk to groundwater conditions than the conventional excavation methods that will be used for the stations. The project has been dogged by delays associated with environmental concerns that saw its original start date of late 2003 slip by over a year. It was not until this spring that the construction phase of the project was launched, (T&TI, June, p6).

The 17km long rail scheme will connect Malmö Central Station and the Oresund Bridge; bringing together the rail systems of southern Sweden. Current schedules envisage the entire works to be finished by 2011.