Murphy's Lovat in London tunnelling

Within weeks of a Lovat TBM being launched by J.Murphy & Sons for a cable tunnel extension in London, a source from within the TBM manufacturer told T&TI that the contractor had also chosen the company to supply two TBMs for the Lower Lea Valley cable tunnel project (T&TI, September, p13).

Murphy was awarded a 1.4km long extension to a high voltage cable tunnel in Central London by EDF Energy following successful completion of the main tunnel, the Bankside to Farringdon cable tunnel, that crossed under the River Thames. The contractor will use its MP 116SE Lovat TBM, christened "Bernice", to drive the extension through London Clay and install 2.59m i.d. precast concrete wedgeblock segments.

The TBM was dismantled down to manageable sections for transport 1km along the main tunnel to an 8m diameter junction 20m long. The TBM was then re-assembled and launched from the junction in August.

On 24 August, Murphy was announced as the selected contractor for the 12km Lower Lea Valley cable tunnels by the London development Agency. Within a month of the announcement, T&TI was told that Lovat had been chosen to supply two TBMs for the scheme that will see the removal of 50 electricity pylons, freeing up 40 hectares of land for development associated with London's hosting of the 2012 Summer Olympic Games.

A source told T&TI that Lovat was "very proud to be able to participate" and would be refurbishing two out of the four TBMs previously used by the Frontier-Kemper Constructors jv to build the 18.5km of sewers that make up Los Angeles' North Outfall Sewer – East Central Interceptor Sewer (NOS-ECIS). The first of these machines, delivered to the NOS-ECIS site in late 2001, was the 200th machine manufactured by Lovat.

The 197t mixed face machines will excavate in open or EPB mode T&TI was told. The alignment passes below or close to several significant features such as rail and road corridors, the Northern Relief Sewer, gas works, the Channel Tunnel Rail Link, river crossings and buildings. In addition, most of the tunnel alignment is below the water table, with groundwater levels reaching a maximum of 14m above the tunnel invert.