Crossrail The Elizabeth Line

InSAR monitoring of the Crossrail project in London

Crossrail (The Elizabeth Line) is a 117-kilometre railway that traverses London from East to West. The construction phase of the project began in 2009 with an estimated cost in excess of £17 billion. The main challenge, for which the Atlas InSAR technique was pivotal, was monitoring the 21km of twin tunnels running from Paddington to Stratford and Canary Wharf below the city.

Atlas InSAR historical study of the site prior to construction, regular monitoring with monthly updates throughout the construction phase, and continuing post-construction monitoring with quarterly updates using high-resolution imagery.

Crossrail is the first construction project actively using InSAR as a technique to reduce monitoring costs. Atlas InSAR monitoring was performed before and during the construction of the tunnels and is still ongoing to analyse residual settlement. The study area monitored includes a corridor 2km wide over the tunnel alignment, covering a total area up to 36km2.

Monitoring

• Atlas InSAR is successfully being utilised on Crossrail providing precise ground surface and building movement measurements along the area of interest whilst concurrently delivering significant benefits such as monitoring areas with complicated geology (where ground conditions were not as expected); providing a third-party movement validation solution whenever clients and contractors have discrepancies; validating primary benchmark stability; mapping all heritage property with a focus on those with abnormal behaviour; providing asset owners protection against damage claims and litigation.
  Furthermore, it has enabled accelerated decommissioning of ground instrumentation while maintaining the control of the monitoring process.
• The area of interest is being continuously surveyed providing almost one million measurement readings every 3 months. Atlas InSAR has proven to be an efficient and cost-effective tool for the long-term monitoring of construction works and built environments.