As Crossrail’s progress approaches 75 per cent completion we explore the innovations and challenges of the complex railway systems phase
When it enters operation in December 2018, Crossrail’s tunnelled section, which passes through Central London and Docklands, will mark the beginning of the end of one of the UK’s biggest construction projects in a generation. Making its way from Royal Oak in the West all the way through to Pudding Mill Lane and Plumstead in the East, over 50km of track –- which will be known as the Elizabeth Line when the railway opens – will make its way through newly formed tunnels beneath London, passing through ten new stations and onto mainline track to Reading and Shenfield. As the extensive tunnelling work drew to completion in 2015, the installation of the railway systems is now in full swing. Taking on the main works of this phase is ATC – a Joint Venture between Alstom, Transports Sud Ouest (TSO) and Costain.
Speaking at the start of June 2016, Crossrail’s Construction Manager for the railway systems phase, Gregg Purcell, gives us an overview of the programme’s progress so far.
In the Eastern section, which begins at the Plumstead railhead, track has been installed all the way up the South Eastern branch to Stepney Green where it meets the North Eastern branch coming from Pudding Mill Lane. The 465-metre long concreting train is following this closely and is currently in operation five nights a week. Out in the west, track has been installed from the Royal Oak portal through Paddington Station to Bond Street, with concreting here taking place three days a week.
Throughout Crossrail’s tunnelled section, five different types of track are being used. Eighty per cent of this will be made up of standard track slab, with direct fixed track being installed in the Victorian-engineered Connaught Tunnel and a few small areas benefitting from high attenuation sleepers, which further reduces noise and vibration. However, in two sections underneath Central London, Crossrail is making use of innovative floating track slabs (FTS), which significantly reduce noise and vibration in sensitive areas, with a light version being used under Soho and a heavier one underneath the Barbican.
Using the Fisher Street shaft as the main construction hub for FTS, 1.97km of the light system is currently being installed under Soho, with around 85 per cent of reinforcement cages already put in place to receive the specialist concrete system. “We are looking to start concreting here from the middle of June, and hope to complete a fairly rapid plan of about three months,” Gregg explains. “At the end of May we also took possession of the Barbican section from the Farringdon team, which means we can now commence work on the 1.34km FTS (heavy) installation.”
In terms of M&E systems, equally significant progress is being made in the Eastern phase. “From Plumstead we are quite far advanced into the Thames Tunnels with installing physical infrastructure, such as Overhead Line Equipment (OHLE) systems and bracketry for all the permanent cable systems,” Gregg outlines. “In the North East branch our drilling rig is making good progress to prepare those tunnels as well. Temporary services such as tunnel ventilation, which will be completed by September 2016, and safety systems like the fire mains, are also making good progress – as are the permanent ventilation installations at Canary Wharf, Whitechapel and Tottenham Court Road.”
Unsurprisingly, a project of such scale and complexity is not without its challenges. Chief amongst these is to maintain a consistent output of work to meet the tight deadlines posed by the Crossrail programme. “Whilst the timeline is highly achievable, it does require us to keep to a very tight and efficient programme,” Gregg explains. “This include being able to overcome any unplanned challenges – mechanical, plant or even human issues – quickly and effectively. Our 23-wagon concrete batching plant, for instance, is nearly half a kilometre long and has around 2500 individual components and systems. Law of averages will suggest some things will go wrong, so we have to be prepared for this.”
Access through stations and shafts, which are increasingly lively development sites, too, also poses significant complexity, with Gregg noting that interface management between the station and rail systems teams is essential to overcoming these. “I was told quite early on that this project would get built because of the people and the relationships, and this has turned out to be absolutely correct,” he says. “I spent a lot of time at the beginning developing relationships with various station teams, explaining what we need and understanding their needs, so that we can all remain professional and do the best to accommodate each other. This is by far the most logistically complex and interface-heavy project I have ever worked on so this approach is absolutely vital.” Despite the extraordinary complexity of Crossrail, the development programme has proven to be an exemplary showcase of innovation. Four Multi Purpose Gantries (MPG), for instance, have been developed especially for the Crossrail tunnels, allowing t
he team to handle a range of materials and activities, including the accurate positioning of 70,000 sleepers and 57km of rail, and achieve incredibly high outputs within a single bore tunnel environment. “The MPG solves a whole host of issues,” highlights Gregg. “In terms of pure innovation it’s one of the cleverest pieces of plant I have seen in a long time. Working through the tunnels is a very linear activity, which means we can take a slightly more production line mentality when approaching it, which the MPG supports, but it also provides the ability to magnify operations over 42km and develop some unique solutions in a slightly bigger context.”
One such solution is the use of a multi-access manipulator – technology borrowed from the tree felling industry. Used to help install fire mains systems, the highly flexible robotic arm has been attached to a Unimog and is able to manipulate long lengths of pipe into position whilst eliminating much of the human interface and therefore creating a much safer working environment. “It also allows us to maintain a very high standard of output with a very high quality level in a much safer manner,” adds Gregg.
Removing the human element from much of the physical process has been a key feature in the development of Crossrail’s one-of-a-kind drilling rig, as well. Using cloud surveying to digitally map the tunnels to a very high degree of accuracy, positions for the 250,000-plus holes – to support the installation of bracketry and walkways – are programmed into the drilling rig, which then uses a series of robotic drilling arms to carry out the work. Capable of running on both track and concrete, the drilling rig has been designed to be highly flexible in achieving high output and an effective workflow. In the North Eastern branch, for example, the drilling rig is completing its work before the tracks have been laid, whilst in the South Eastern the opposite occurred. Logistically, this enables the team to make significant progress on each section concurrently.
“With many of these innovations we have been able to maintain the human element as the intelligent component organising, planning and programming the heavy duty labour, which can be carried out by a machine,” Gregg outlines. “Of course, final connections, fixings and fittings still have to be carried out by people, but we have significantly reduced the risks.” This ties into Crossrail’s overarching health and safety programme, which focuses on behavioural safety just as much as it does on mechanising processes. “We run numerous behavioural-safety and front-line leadership initiatives to ensure that the right decisions are being made,” Gregg continues. “This is supported by some very sophisticated root-cause analytics, which enable us to interrogate an incident right back to its origin and take appropriate preventative action accordingly.”
The Crossrail project is undeniably vast, but the way it has approached such unprecedented complexity by applying intelligent innovation alongside close co-operation is extraordinary. Gregg’s enthusiasm for taking on such a key project typifies the level of expertise and passionate professionalism across that thrives off of delivering such a critical piece of infrastructure to the people of London right across the programme. This is set to continue over the coming months, when numerous short-term milestones are set to be achieved, each marking even greater progress for Gregg and his team.
“In June we’ll start concreting our FTS systems, in July we will turn our concreting train around 180 degrees and in September we’ll be commissioning our temporary ventilation system,” he outlines. “There are lots of challenges ahead, but we have good momentum and all of these phases take us one step closer to November 2017, when we can start handing the tunnels over to rail operators for the beginning of dynamic testing.”