Dock Street Tunnel, Dundee

Client:Dundee City Council
Value:£5,900,000
Location:Dundee

Amco carried out the contract to strengthen the Dock Street Rail Tunnel on behalf of Dundee City Council. The contract was a key element of the enabling works for the city’s 30 year £300m Waterfront Development.

Before progress could be made on the above ground infrastructure, major preparatory work had to be completed below ground and in particular strengthening the roof of the 575m long 125 year old rail tunnel to enable full highway loading across its 7.62m span.

Awarded preferred contractor status in May 2005 Amco worked in partnership with Dundee, their designer Donaldson Associates and key stakeholder Network Rail to develop a robust scheme with surety of delivery. Through a process of value engineering an over-slabbing solution was selected, which effectively isolated the rail tunnel from future loading without requiring alteration to the existing tunnel structure. Importantly this approach minimised the environmental impact on the local community of night shift working, allowing the work to be undertaken during the day and without disrupting the train and freight operating companies.

Whilst the theory seemed relatively straight forward, applying it was anything but as working on a live Network Rail tunnel located in the city centre with heavy traffic made it an exceedingly complex project.

The works were further complicated by the main east coast rail line running through the tunnel. A remote-monitoring system was installed and the original cast-iron beams were fitted with electro-level sensors to detect any movement. This provided continuous real-time feedback relating to the impact of any surface work.