Tideway Tunnel nears halfway point ahead of schedule
Construction activity on the Thames Tideway project, London’s super-sewer, is now 48% complete.
Excavation work on the interception chamber at Hammersmith Pumping Station site completed in September
Excavation work on the interception chamber at Hammersmith Pumping Station site completed in September
Bazalgette Finance, the investment vehicle behind the £3.8bn project, issued a half-yearly report this morning, revealing that shaft completion and tunnelling are ahead of plan.
Four of the six tunnel boring machines (TBMs) are in the ground and tunnelling, with a further two due to start in 2020. So far, 7.4km of the 25km of main tunnel has been dug.
All eight of the Thames cofferdams needed for the project have been completed; nine of the shafts are excavated with a further eight in progress and four yet to start.
Twelve milestones were meant to have been hit by now; in fact 13 have been achieved.
The project is also committed to ‘transformational standards’ of workplace health & safety, and managed to avoid any life-changing incidents during the six-month period ended 30th September 2019. There was, however, ‘a significant incident’ at the Greenwich site, relating to a lift of heavy machinery, which resulted in one lost-time injury and damage to plant. Tideway says in the report: “Following this we have worked with our main works contractors to refocus on lifting operations and exclusion zones. Each area has developed shaft lifting and exclusion zone guidance, based on a common approach agreed across the programme, which has been communicated across all sites."
On the western stretch, being built by a joint venture of BAM Nuttall, Morgan Sindall and Balfour Beatty, TBM Rachel was launched in May from the Carnwarth Road site in Fulham. She has bored through 800-metres of London clay and will complete her journey when she arrives in Acton in 2020. At Acton the team completed the shaft and poured its base in July. Charlotte, the second TBM for the west, began her journey to King George’s Park earlier this year and has now completed more than 32% of her journey. Once she arrives at King George’s Park she will be taken out and taken back to Dormay Street. From there, she will be lowered back into the shaft to complete her journey to Carnwath Road, creating the Frogmore Connection Tunnel.
In the central section, being built by FLO JV (Ferrovial Agroman UK and Laing O’Rourke), the two TBMs have made good progress. The eastbound machine, Ursula, was launched in March and has completed 1.9km on her journey towards Chambers Wharf in Bermondsey. Her sister, Millicent, has been tunnelling westbound towards Carnwath Road for the past nine months and has completed 90% of her 5km journey. To date, more than 900,000 tonnes of spoil has been removed from the tunnel drives by river, avoiding around 115,000 lorry movements. At Albert Embankment, the primary lining of the first connection culvert in the central section is complete. A number of other sites are moving below ground, with shaft excavation well under way at Heathwall Pumping Station, Victoria Embankment and Blackfriars Bridge, with Falconbrook Pumping Station, Cremorne Wharf and Chelsea Embankment soon to begin following completion of piling activities.
The east area team, CVB JV (Costain, Vinci and Bachy Soletanche), has also continued to make good progress across all sites. At the Chambers Wharf site, the main drive site for the east section of the project, a 64-metre deep shaft has been constructed. Over the summer, the team carried out a 36-hour continuous concrete pour to construct the base of the shaft. King Edward Memorial Park has seen work to improve ground conditions with deep soil mixing and diaphragm walling to construct the shaft due to start in the autumn of 2019. Across the rest of the east sites, have shafts have been excavated at Greenwich Pumping Station and Deptford Church Street. The Greenwich Connection Tunnel’s TBM, Annie, is currently being reassembled and should arrive at the Greenwich site early in 2020.