Water ingress can be a significant risk factor for underground cable installations but innovative DOYMA technology from Germany can be used to address that risk.
At Victoria Underground Station, where Transport for London is investing in a significant upgrade programme, the electrical installation includes connecting a new build ‘North Ticket Hall’ to the existing South Ticket Hall and Mott MacDonald has designed the power and comms cables installation to follow a route outside of the building under the adjacent road.
Palan Senthoor from Mott MacDonald, said: “In order to route the services outside of the building bus lanes had to be closed and street furniture had to be removed. The tarmac was then stripped back so that the installation team could access the existing services and re-route them.”
To minimise disruption to the public while the work was carried out, one of the key objectives was to find practical solutions that would fast track the installation. One of the innovative solutions found to address this need was the use of the DOYMA service duct sealing system, supplied by UK distributor, Interflow UK.
Villiers Chillcott from Interflow UK, commented: “The service ducts needed to be installed through the wall of both the North and South ticket Halls below ground level and where the ducts penetrate the walls there could be a potential risk of leaks from the water table if a suitable sealing system was not used. The DOYMA system is guaranteed for 25 years and has an anticipated service life of at least 125 years. It utilises German engineering expertise to ensure that no water or gases can infiltrate the building, preventing the risk of structural damage.”
The installation team dug an 11m trench for installation of the cable ducts and two manifold DOYMA service duct penetration plates were custom-specified and manufactured for each of the two ticket hall structures.
Palan Senthoor, added: “Interflow UK were able to work with us on the design and specification of the DOYMA plates so that we could be confident that the product supplied would meet the project requirements. The company not only supplied the plates in line with the tight installation programme but also expertly installed them to provide a fast solution and complete peace of mind.”
On the wall of the South Ticket Hall the existing tanking was stripped back before the DOYMA plate was put in place and the required penetrations were created in the wall to allow the service ducts through. The DOYMA plate is fitted with sockets that enable the service ducts to be connected directly to the plate and, once this connection has been made the service penetration is completely water tight. As an additional failsafe, the installation was then completed with new tanking overlapping the existing tanking and the DOYMA manifold plate.
For the new wall of the North Ticket Hall the installation process was identical. Once both connections had been made successfully, the installation of the power and data cables which will link the two ticket halls could be carried out. This entailed laying 11 x 11 metre DOYMA KSS cable ducts between the two manifold plates – chosen for its flexibility combined with exceptional crush resistance.
The service connection between the new-build North Ticket Hall and the existing South Ticket Hall has now been completed and, thanks to surplus capacity in the service manifolds, the installation is not only built to last but future-proof too. However, this is only the beginning of a much longer journey for Victoria Underground station, with the extension works to the South Ticket Hall due to begin later this year and completion of the whole programme not scheduled until 2018.