Technical challenges are no hold-up to Manchester Metrolink

Constructing Manchester Metrolink Phase 3, the largest light rail scheme in the UK with 60km of new track to be laid and 55 new stops to be built, was technically always going to need a high level of efficiency and problem-solving. But problem-solving is one of Tubosider’s great strenghts.

VolkerRail and Laing O’Rourke were awarded the contract in joint venture with Thales in 2013, with VolkerRail and Laing O’Rourke responsible for the design, construction and maintenance of the civil engineering and track, and Thales responsible for the tram operating systems.

When Laing O’Rourke’s Expanded Structures division came to installing the new track and stops at Manchester Airport, Tubosider’s first planned stormwater solution ultimately needed considerable reworking – but all in response to various unforeseen changes in available space and discharge criteria.

At the start of building the line alongside the Airport, a conventional helibore steel tank of suitable capacity adjacent to the incoming flight path looked to provide a complete answer to requirements – and at the most competitive price.
But at this critical stage in the project, the culvert due to serve it was transferred in authority from Manchester City Council to the Environment Agency, and the allowable discharge level was halved at a stroke.

“One of the big positives about working with Tubosider, though, is that they have their own design team, a skill which also extends to the area managers who are on the ground working with clients like us,” says Expanded’s project manager James Swales.

“Having to reduce the footprint of the first tank really put pressure on us, but we could call on Tubosider at any time to adapt the design and change the size and layout. Plus of course their area manager Neil Prescott was quickly on the spot with his laptop to liaise with ourselves, the engineers and the two authorities to propose and agree the best solutions there and then.”

The decision was taken to reduce the footprint of the first tank to four legs measuring a total of 27.3m long x 13m wide, all constructed in 2800mm diameter pipe to give a capacity of 1000m³.

The remaining storage requirements could then be accommodated by fitting a smaller Twinstore tank and flow control system into the tight space between the new Ringway Road and the Metrolink carriageway.

The advantage of Twinstore, a Tubosider system new to James Swales, is that its pipe ends are unsealed to allow water storage to balance out into the surrounding backfill, which is lined with an impermeable membrane.

This second 3 leg tank of just 1400mm diameter, with a footprint of 41.6m long by 5.4m wide, provides much more than its dimensional storage capacity of 280m³. But with the tanks able to be take more weight to help positioning, between them they offer an even more cost effective solution to both carriageway and Metrolink track drainage alongside the Airport.

Efficiency really has to be the name of the game on the Manchester Metrolink Phase 3 contract, which is valued at £900 million and will see the network treble in size to become the UK’s largest.

Light rail is a must-have for every large city, tackling key urban priorities such as congestion and carbon emissions. This project is immense, so in an unprecedented alliance, the area’s 10 local authorities are each part-funding the extension, together with a central government contribution.

New lines will carry passengers to Oldham and Rochdale in the north, Ashton-under-Lyne in the east, and south to East Didsbury and Manchester Airport. At the same time, tram management systems from the existing network are being upgraded to integrate with the new lines.

As Transport for Greater Manchester (TfGM) Metrolink director Philip Purdy says, “There are big political and public expectations. The sooner we can open a line, the sooner we start making revenue to contribute to the initial investment.”

That means speed is of the essence. Laing O’Rourke has responded to this challenge, not least in the introduction of Design for Manufacture and Assembly (DfMA) techniques for the first time on a UK rail project, and the whole programme is on track to be finished by 2016.