Crossrail C315

Project summary

Service provided:  Structural and Geotechnical Instrumentation and Monitoring
Location:  London, United Kingdom
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Images of the project

Converting Victorian twin tunnels

The Victorian Connaught Tunnel is over 130 years old and 550 metres long. It runs under the Royal Docks in East London.


It is being refurbished to form an essential component of the Crossrail Abbey Wood branch. The site lies between the proposed Custom House Station and the North Woolwich portal of the intended Thames tunnel. About half is in tunnel and the remainder in cutting or above ground.


VINCI UK is converting the existing twin tunnels into one larger tunnel so that Crossrail trains can be accommodated along with the overhead line equipment.



Structural and environmental

Sixense is providing the structural monitoring of the tunnel and adjacent structures to the construction activities using a combination of Automatic Total Stations (ATS) working in groups, known as Cyclops and traditional instrumentation.


In addition, environmental monitoring including vibration monitoring of Thames Water supply pipe and noise monitoring according to local authority statutory requirements (section 61 consents) is also being provided by Sixense.



Installation by divers

Underwater instrument installations were necessary during the dewatering at the Royal Albert Docks in order to monitor the Cofferdam. Installed by specialist divers, this instrumentation provided real-time monitoring of the Cofferdam and the North and South retaining dock walls. All the data from the instrumentation was transmitted remotely which can then be visualised in the office or on the web via the bespoke Geoscope Monitoring Software.


Sixense also provided structural and environmental monitoring in the service tunnel adjacent to the Connaught tunnel, with a series of Electrolevel beams and tiltmeters installed in the confined spaces.

Project Key figures

26 AutomaticTotal Stations (Cyclops)
5 Load Cells
14 EL Tiltmeters
28 Electrolevels
16 VW Strain Gauges