New challenges facing east and west

Chris Binns was the head of engineering for the £6.5 billion Thameslink programme for six years, one of Network Rail’s biggest infrastructure challenges to date. However, in June 2015, he swapped the north to south London line project for the new east to west link now under construction known as Crossrail. Chris became the chief engineer of this £14 billion project which is, without doubt, Transport for London’s (TfL) biggest infrastructure challenge to date.

Chris replaced Chris Dulake who, now that the tunnelling work and associated heavy civil engineering (his speciality) has been successfully completed, has moved on to an even bigger project, the £50 billion High Speed 2 line. Chris Binns now reports to Crossrail’s technical director, Chris Sexton. Yes, another Chris!

Rail Engineer visited Chris Binns recently to find out how life in his new role is panning out for him now that he has completed his first six months. His immediate response was “responding to the sheer volume of technical challenges”. He added that these challenges are not necessarily more complex than those he experienced at Thameslink, but the scale has increased significantly.

As readers will be aware, unlike the Thameslink project, which is being successfully built around a fully functioning urban railway, Crossrail includes a new central core consisting of 42km of newly bored tunnels. There are also 10 new Crossrail stations being built, some in very complex locations – Paddington, Bond Street and Liverpool Street to mention a few. In addition, there are complex redesigned track layouts both west and east of the capital, extending out to Reading in the west and Shenfield in the east.

Area of expertise

The tunnels and the new stations all need fitting out, while new power supplies have to be installed alongside signalling and control systems. These are the challenges that now face Crossrail and this is the area of expertise that Chris is most suited to, hence his appointment to this post.

As with Thameslink, all the different technical heads report to Chris. However, Crossrail’s expenditure is three times that of Thameslink and, because of the significant volume of work and diverse issues that they have to cover, Chris has a large team of 200 plus engineers which is not far off double the resource at Thameslink. He was keen to point out that the Thameslink team were of a high calibre, but one of the benefits of Crossrail is that it is considered to be probably the biggest railway project in Europe if not the world, and this again means he is working with another very high calibre team.

Key suppliers

Of course, none of the fitting out work of tunnels and stations can be carried out without the support of a competent and innovative supply chain and, in April 2013, Crossrail awarded the last major suite of contracts valued at £300 million, to a joint venture comprising Alstom Transport, French trackwork specialist Transport Sud Ouest (TSO), and Costain. The joint venture is normally referred to as ATC and it has the responsibility of ensuring that the tunnels are fitted out with the necessary equipment for an operational railway system. This work will be the focus of much of Chris’s attention over the coming months and years, leading up to the 2018 opening.

He explained that, when the tunnels were completed, the construction included a mass concrete base ready to receive the various slab track designs. The base has a raised curb either side, designed to carry a specially built multi-purpose gantry, which at first sight looks like something out of Star Wars. This gantry has the capacity to carry and position 28 sleepers at a time before installing 108-metre lengths of rail.

The 70,000 sleepers required are being manufactured by Nottingham- based SBC Rail and then stock piled in bales at the railhead depots at Plumstead Logistics Centre in south east London and Westbourne temporary railhead in West London. Both locations are being used throughout the contract for providing engineering trains and for storing materials and equipment.

Also, given the recent concerns about the UK steel industry, it was pleasing to note that Tata Steel is supplying more than 57km of heat treated, wear-resistant rail and that the steel blooms are produced in their Scunthorpe plant. The slight surprise is that these blooms are then transported to Tata’s Hayange mill in northern France to be rolled into the rail profile.

Neighbourly awareness

When Chris was at Thameslink he was especially pleased with the way the project team dealt with its neighbours, the sensitivities associated with a new viaduct built across Borough Market being a good example. Chris was eager to point out that this committed approach to the surrounding environment is clearly evident within the Crossrail project as well. One technical example is the creation of five different standards of track designed to cater for such sensitive locations as recording studios in Soho, the Barbican concert hall, and historical listed buildings, to name just a few.

For the majority of track constructed in the tunnels, standard track slab with fibre reinforced concrete is being used. However, in the Victorian Connaught Tunnel, a newly designed, direct fixed track system has been installed, using Australian Delkor two holed baseplates. The design of the baseplates includes a top plate and base frame which are vulcanised together by means of a natural rubber boot. This helps to significantly reduce the dynamic stresses on the base structure.

In addition, a high-attenuation sleeper track design, that is placing whole sleepers into a rubber boot before they are concreted into the formation, is being used in a number of selected areas where there is a particular need to reduce noise and vibration.

Light or heavy?

Where the noise and vibration have to be reduced, in more sensitive locations such as Soho, light floating track slab is used.

However, where noise and vibration has to be controlled in the most sensitive area such as the Barbican, heavy floating slab track is being installed. The concrete in this track is described as magna dense – double the density of normal concrete with a high iron ore content, hence the heavy!

So there is a fair array of options available, all required to be installed to a high specification and in accordance with the very tight tolerances imposed. It is down to Chris’s team to ensure that this level of quality is maintained and, during site visits, the team has been able to verify the high expectations of the surveyors within the production team.

It is not always easy to tell the production team to stop a full-flowing process to make marginal adjustments of just one or two millimetres, but that is the standard that everyone is working to and it is this meticulous approach that Chris finds very reassuring.

Invaluable equipment

The ATC joint venture has acquired a Plasser and Theurer road-rail flash butt welding machine, designed to produce welds to a consistently high standard in a tunnel environment. This will undoubtedly prove to be an invaluable piece of kit as will another new machine – a new drilling rig.

As part of the tunnel fit-out, it has been estimated that more than 250,000 holes will need to be drilled to accommodate brackets for cabling, walkways and other equipment to support the operation of the railway. A state of the art drilling rig, owned by Crossrail and manufactured by Rowa Tunnelling Logistics in Switzerland, is now being used to drill the majority of the holes, thus minimising the need for manual drilling.

Once the slab track has been laid, the rig sits on the track and is designed to move through the tunnels drilling the holes in pre-determined locations. The machine has a dust suppression system in place, helping to produce a clean and accurately drilled hole every time. The rig is configured to work in conjunction with real-time 3D laser surveys of the tunnel to ensure accuracy, and it is proving to be an invaluable piece of equipment for all concerned.

Dry and wet

Crossrail has also invested in a refurbished concreting train that was brought to the UK from France via the Channel Tunnel in August 2015.

It is 465 metres long and is a mobile underground concrete batching factory using dry materials. Running and maintaining the concreting train is a 24-hour operation. Concrete pouring generally takes place during the night with restocking and maintenance carried out during the day.

The train is based at the Plumstead rail depot and is being used for the construction of standard track slab. At first, the production team was achieving about 74 metres per day, but this has now increased to around 150 metres per day, which is a considerable achievement. The train has piping running from the front of the train, like a giant insect proboscis, for about 300m. This means that the train does not have to run on freshly laid concrete the next day allowing the concrete adequate time to gain strength.

Also, a different, smaller concrete train known as the Shuttle, was brought into action in January 2016. Chris explained that the Shuttle is being used to construct the standard track slab in the tunnels from the Royal Oak Portal through to central London. The train was designed to accommodate the limited room available at its stabling point in Westbourne Park. However, because the train uses batches of ready-mixed fibre reinforced concrete, time becomes a critical factor.

Power supplies

The Crossrail route will be powered by a 25kV overhead line system using a rigid overhead conductor bar throughout the tunnels, a design that doesn’t require weights and pulleys. As Chris pointed out, it is a similar system to the one used in the Thameslink Canal Tunnels that linked the East Coast main Line to St Pancras and beyond.

In the central section, 25kV traction power for the Crossrail trains will be provided by two new bulk supply points, connected to the National Grid 400kV supply, at Pudding Mill Lane in the east and Kensal Green to the west. Super grid transformers have been installed and are currently being ‘dressed’ (fitted with fans, coolants etc).

A 22kV high-voltage network will be installed in the central section from Royal Oak Portal in the west to Limmo Peninsula in the east with an 11kV high- voltage non-traction spur to be installed from Limmo through to Plumstead. This network will supply mains power to each Crossrail station, shaft and portal within the central section.

With regard to the signalling systems, Thameslink is using a novel combination of metro Automatic Train Operation, and the main-line European Train Control System (ETCS), with a recent trial run through the core section of the route going very well. Crossrail, on the other hand, is using a Communications-Based Train Control System (CBTC) for its core.

This system is popular with Metros throughout the world and is familiar to TfL. Therefore, development costs are more predictable and Siemens has just commissioned a similar system in Copenhagen in February 2016 so, lessons learnt will be transported into the project.

As Chris pointed out at the start, the scale and volume of this project is enormous with a myriad of Crossrail’s communications and control systems.

When asked if he was enjoying it, he replied “thoroughly!” and then added that he had just finished his first induction session for new recruits into Crossrail so now he really feels that he is part of the team facing the challenges of building a railway that will stretch from Reading, across town to Shenfield, by 2018.