Monitoring London Underground assets during the demolition works for the Tottenham Court Road over station development

As part of Crossrail 1 the Elizabeth Line, Europe’s largest infrastructure project, the existing Tottenham Court Road station is being upgraded. Part of the works also includes a new over station development, comprising retail and office space across two buildings.

Developing above and around transport infrastructure in one of the busiest areas in Central London is complex – existing structures must be retained and safeguarded, and the operation of the busy railway must not be compromised. The first phase of the over station development works involves the demolition of several existing structures along Oxford Street. Working with McGee, one of the leading demolition contractors in the UK, in January 2018 ITM Monitoring was contracted to install a manual monitoring system to measure the impact of the demolition works on several London Underground assets located in close proximity – the new Tottenham Court Road station entrance at the North East end of the site and the Falconberg Mews building on the West side of the site.

ITM Monitoring installed four mini ‘L’ Bar prisms on each of the two LU buildings, with BRE style levelling points on the facades of the buildings located below the prisms, to monitor any vertical movement of the structures caused by the demolition works. To monitor heave and settlement in the surrounding area, brass levelling studs have been installed in the ground within the site and in the kerb stones of the pavements outside the site. 11 levelling studs are located around the perimeter of the two buildings within the site and, outside the site in the pavements either side of Oxford Street, a further 17 are installed on the South pavement and 15 on the North.

The first set of baseline readings were taken at the end of January, followed by a schedule of monthly manual monitoring for five months during the demolition phase. Monthly monitoring will continue for an additional three months post-demolition, with a further four months of bi-monthly monitoring. Following each monthly surveyor site visit, the readings are sent to ITM’s technical department to input into Calyx for data processing and visualisation. A monthly report is produced for the client.

These monitoring works are the prelude to the main works contract, which ITM is pleased to be working towards, and which will involve monitoring the impact of the construction works on the London Underground and Crossrail running tunnels.