Due to the proximity of the CTRL route, London Underground (LU) is installing safety monitoring equipment in both Central line tunnels while the tunnelling takes place. In addition, it is carrying out engineering works to help reduce any possible risk.

LU is also working with mainline train operating companies and bus service provider, Transport for London to have a contingency plan on hand should there be any disruption to services.

An LU spokesman said: "The tunnelling machines are designed to minimise ground movement and we expect CTRL to carry out this work without any problems or delay.

"Nevertheless, safety is LU's top priority and we are keen to ensure that this work does not affect the existing Central Line tunnels.

We will therefore be checking the progress of the CTRL construction using state-of-the-art monitoring equipment.

"Though we do not anticipate any problems, LU is developing a full contingency plan with local train operating companies and Transport for London, so that, in the unlikely event that the Central Line service is affected, alternative travel arrangements for our customers will be provided."

LU gained extensive experience in managing this situation during the construction of the Jubilee Line