01.07.16
Plain sailing for the Northern Line extension?
Source: RTM Jun/Jul 16
RTM’s Luana Salles runs through the latest updates of TfL’s Northern Line extension, intended to regenerate the local area and improve transport links in the capital.
Despite anxieties in late May that design changes to the Northern Line extension to Battersea Power Station could hike costs by £240m, the project seems to be progressing smoothly, with Morgan Sindall recently deciding to re-open its precast factory in Kent as a result.
The factory’s last major project was the delivery of the Lee Tunnel in London in 2014. But after receiving a £8m order from the Ferrovial Agroman Laing O’Rourke (FLO) joint venture – responsible for designing and building the extension – the company decided to fire the facility back up.
Based in Kent, the facility will manufacture bespoke concrete segments to tight tolerances which slot together to form tunnel rings. The new order requires 3,280 concrete tunnel rings, which will be 5.2m in diameter and line 2.4km of twin tunnels. The Ridham team – 45 people working over two shifts – will be able to manufacture 70 tunnel rings a week.
Announcing these plans in late June, David Hicks, the company’s senior operations manager at the facility, said the decision to re-commission the factory came just a few days before production kicked off in July.
Design changes
But despite the ongoing progress, TfL’s Finance and Policy Committee met back in April to discuss the need to approve supplemental agreements with the developer after the extension’s design became “very different from that originally intended and contracted”.
News then emerged in late May that these design changes included a new ‘station box’ to allow passengers to emerge directly from the station into the Prospect Place complex of apartment buildings.
TfL announced it was in talks with the consortium of three Malaysian companies – SP Setia, Sime Derby and the Employee’s Provident Fund – to decide who would be responsible for footing the bloated bill. Although costs had not yet been calculated, it was rumoured they could add £240m to the overall project cost.
First major milestones
TfL and FLO recently announced that a major milestone was achieved in the Battersea worksite in April with the completion of the diaphragm wall in the crossover box nested behind office cabins, which is “essentially a reinforced vertical concrete wall built around the perimeter of the area where the future trains will cross over before continuing their journey”.
Completing this has enabled the construction partners to kick-off the first stage of the excavation works.
“Following the completion of the temporary works i.e. guide wall installation, diaphragm wall construction is now under way in the station box to the west of our site. The next phase of works will follow the same sequence of activities that have taken place in the cross over box,” they said in a statement. “These works are currently progressing according to programme.”
Photos also surfaced in mid-March of the two 650-tonne tunnel boring machines that will be used to build the extension under south London. A 3.2km twin-bore tunnel and two new Tube stations will be built by 2020: one at the heart of the Battersea Power Station redevelopment and another at Nine Elms to the east. Main tunnelling from Battersea to the new shaft at Kennington Green and Kennington Park is expected to start early next year and will take six months to complete.
Station fit-out is then due to start in 2019 ahead of testing and commissioning the following year, when the extension will enter full operation. It is expected to greatly improve transport links and public spaces in the area, with journey times from Nine Elms or Battersea to the West End or the City adding up to less than 15 minutes in some cases.
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