Victoria Station Upgrade - Protection of Sensitive Structures during Tunnelling

"1. THE VICTORIA STATION TRANSPORT HUB Victoria Underground station is part of the Victoria transport hub, which comprises one of London’s main train termini and a major bus station. At the Underground station, the District Line running in the older shallow brick tunnels dating back to 1868 cross the Victoria Line running in the lower tunnels, which were opened in 1969. After Waterloo, Oxford Circus and King’s Cross/St. Pancras Tube stations, Victoria is the most frequented station on the London Underground network and is used by over 80 million passengers per year. Capacity at Victoria Tube station has been inadequate for many years with passenger numbers steadily rising. Overcrowding is a constant challenge and the station has to be closed regularly during morning and evening peaks until sufficient trains pass through to clear the platforms. For this reason an extension has been debated since the 1990s. After intensive preliminary investigations and feasibility studies covering many variants, which included a large-scale jet grouting test to determine the applicability of this technology as a protective measure for the tunnelling works, the project was officially started with the Victoria Station Transport and Works Act Order (Secretary of State, 2009) effective on the 18th of September 2009. Following a competitive tender process a joint venture of Taylor Woodrow and BAM Nuttall were awarded the contract by London Underground, with their design being carried out by Mott MacDonald Ltd. Ensuring the busy station remained open to the public was a key requirement of the Victoria Station Upgrade. Jet grouting works, which were executed from ground surface, were also carried out while the station was fully operational 2. OVERVIEW The Victoria Station Upgrade aims to increase the capacity of the Underground station significantly and one of its major design objectives is to optimise the transfer between the Underground lines. In order to achieve this, the following new structures are currently under construction: •,A new North Ticket Hall •,Extension of the existing South Ticket Hall •,Nine new escalators •,Connecting tunnels between the North and the South Ticket Hall •,8 new lifts providing step free access to all platforms •,An improved connection between the rail/bus terminus and the Underground station As the elevation and geometry of the existing structures cannot be changed, the new structures need to be adapted to the existing structures (see Figure 1)."