Seven into Four does go – at Thickley Wood footbridge

27th September 2019

IMG20190328100205 RESIZED — The refurbished main span of Thickley Wood bridge.

Thickley Wood footbridge at Shildon, County Durham, is unusual but reflects the growth and decline of the local coalfields. Spanning the historic Stockton & Darlington Railway, this bridge dates from 1857, at which time it was a cast iron span of 16.5 metres over the Darlington to Bishop Auckland line.

As the collieries expanded to meet the demands of Victorian Britain’s industries, so were additional sidings required. In 1868, a second wrought iron girder span of 10.9 metres was added to the south and, in 1875, four additional wrought iron lattice spans, one of 7.7 metres and three of 15.2 metres, were added to the south. At this time there were two running lines and six sidings passing below the bridge.

Although, there had been 27 miles of sidings around Shildon at their peak, by 2018, there were just two running lines and a single siding passing beneath the bridge, with the first three spans being redundant.

The sidings at Shildon in their heyday, with Thickley Wood bridge in the background.

The bridge carries a footpath, much used by walkers and recreational visitors to Thickley Wood. The bridge is just 40 metres to the east of ‘Locomotion’, part of the National Railway Museum.

The oldest section, ‘span 7’, is cast iron and is listed Grade II because it is “a single casting of exceptional length”. This includes a maker’s plate, ‘HARRIS MDCCCLVII MAKER’. John Harris was the Stockton & Darlington Railway’s resident engineer from 1836 to 1844. He then became self-employed, and one of his many businesses was Hopetown foundry, in Darlington, where he cast this bridge.

It was recognised by Network Rail that parts of the bridge were in very poor condition and that substantial investment would be required to return it to full strength.

Seen in 2017, the bridge’s poor condition contrasts with the modern Locomotion museum alongside.

Local concerns

The 1825 Stockton & Darlington Railway was the birthplace of Britain’s railway system and was designated in 2018 by Historic England as a Heritage Action Zone. This is part of a five-year project to unlock potential investment into the structures and environment surrounding the Stockton & Darlington Railway with the aim of creating an iconic tourist attraction that will increase economic growth in the surrounding area. As a result, any works around it have the potential to be controversial.

In 2018 Network Rail submitted an application for local authority planning consent for the works as they would affect a listed structure. This described the removal of the redundant spans replacing these with an embankment and the refurbishment of the remaining spans. This being the only realistic economic solution.

These proposals met with much criticism locally. There were concerns that the work would destroy the character of the bridge and the wish was expressed that the bridge should be preserved especially leading up to the bicentenary of the S&DR.

Thickley Wood bridge, before renovation (top) and after (bottom).

Jonny Ham, Network Rail’s project manager, explained: “The design stage was a real challenge and we treated the whole bridge as a listed structure, even though it was only the original three spans that were protected.

“We were conscious that we wanted to be sympathetic to the design of the bridge, so we replicated the original metal latticework in the railings of the new ramped access, and painted the bridge in its original shade of grey”.

In its submission, Network Rail commented: “By maintaining different styles of bridge across the spans, the appearance of the bridge will alter, but this will tell a story of the development of the railway across a period of time. The appearance of the bridge will reflect one altered over the years to accommodate an ever-changing railway and local landscape.”

In March 2018, both Shildon Town Council and Durham County Council considered the application and raised no objections to Network Rail’s proposals.

Design

Leeds-based Construction Marine Ltd (CML) was awarded the £1.6 million contract for the works under its RCDP (Renewals Collaborative Delivery Programme) framework contract. The project at this point was at GRIP 3 (option selection) stage. CML’s Nigel Lea and Mark Anderson explained to Rail Engineer how the project was delivered.

CML prepared an options report, based on Network Rail’s remit, with several alternatives being considered for each of the bridge’s seven spans. Network Rail had liaised over a couple of years with Durham County Council to understand which options were likely to be acceptable at this sensitive location, and this guided the optioneering process.

Span 4, spanning the Locomotion access siding and overgrown siding area, before work began.

There was prolonged and more detailed consideration on costing and practicality of the various options than is usual, to ensure that the planning application would be very detailed, and the logic fully justified.

The agreed solutions were:

The four redundant 1875 lattice side-spans (1-4) would be removed and spans 1 to 3 replaced with an embankment. This was designed to be a reinforced earth structure, reducing fill requirements but also enabling its footprint to remain much the same as the original bridge, and fit within the adjacent boundary fencing of the ‘Locomotion’ museum;
Span 4 would be replaced with a standard LM footbridge welded steel span. The original pier between spans 3 and 4 was to become an abutment, with new wing walls built from masonry recovered from the demolished piers. The reinforced embankment behind the abutment would be self-supporting but a compressible layer between fill and masonry would be provided to ensure that no thrust would be imposed on the slender pier;
Span 5 (1868 span) would be retained and the wrought iron structure repaired and repainted, timber decking refurbished and full height parapet handrails installed;
Span 6 would receive minor masonry repairs and have a lightweight in-situ concrete deck installed;
Span 7 (the listed 1857 cast iron span), would have stitch repairs to its cast iron cross girders, making good poor historic repairs, and would be repainted. This, too, would have a lightweight concrete deck over the waterproofed jack arches, and improved parapets;
In addition, a second embankment would be formed to provide a wheelchair-friendly access ramp up to span 7 from the former track bed, connecting with the foot and cycleway that connects the town to the museum. This was to be funded by Durham County Council and was designed to be easily removable as it occupies a former track bed that might at some point in the future be required should freight expansion take place.

Construction

Before works began at the end of August 2018, the CML project team met with representatives of Network Rail, National Railway Museum, landowners and Friends of the Stockton & Darlington Railway, to fully explain the scope and timeline of the project.

Removing the old Span 3, September 2018.

Following initial site clearance operations, the team installed a temporary 120-metre access road from the site compound, which was established adjacent to the ‘Locomotion’ access road. This was designed to cope with the bulk earthworks deliveries and bridge delivery. Good, regular liaison with the museum team ensured deliveries of plant and materials did not affect their peak visitor periods. Crane pads and a large laydown area were constructed to store the removed and new spans.

The siding into ‘Locomotion’ through span 4, was blocked throughout the project.

On 15/16 September, the four lattice spans were lifted out by a 150-tonne LTM 1150 Crane. The 10-tonne spans 1 and 2 were lifted out during the day and these placed in the laydown area. The crane then de-rigged and moved forward to lift out spans 3 and 4 during a 23:00-06:00 possession of the Darlington – Bishop Auckland line.

During November to January, the new reinforced earth embankment was designed and constructed by Maccaferri using its Terramesh system. This combined the use of galvanised steel cages to face the embankment with geo-fabric tensile straps installed in layers as the embankment was constructed.

The fill for the embankment facing was locally sourced gabion stone, tipped adjacent to the work areas and loaded into the 3000mm wide facing baskets, to create a drystone wall appearance. The central fill was placed by 25-tonne and 13-tonne excavators, a D6 bulldozer and dumptrucks and compacted in 150mm layers by rollers and plates.

Forming the base of the new southern embankment with Paragrid 80/50 reinforcement.

The geotextile straps were installed in sequence with the erection of the facing baskets. Paragrid 80/05 reinforcement was laid every other layer at the face edge. As the works proceeded, temporary scaffold edge protection was attached to the baskets.

Pockets of pre-seeded soil mixture were incorporated into the upper section of the face, which will result in grass-covered walls. The lower will remain stone-faced, matching the adjacent walls of ‘Locomotion’. The new access ramp at the north end was constructed using a mix of reinforced earth and, at the lower ends, natural fill. The steel footway fencing of the south embankment incorporates a lattice design, reflecting the original girders, the north ramp has steel, five-rail estate fencing.

The masonry wing walls and repairs to other part of the structure were carried out by a team from Darlington-based D France Masonry. They constructed the walls using recovered stone from the demolished piers, matching exactly the historic masonry.

The new span 4 was fabricated by Britcon Engineering Services at Scunthorpe and the pre-cast retention units by Ebor Concrete. These were installed in possession by a Liebherr 160-tonne crane – the bridge unit weighed 9 tonnes and this planned lift was delayed by two weeks due to high winds.

The repairs to span 5 were carried out by HS Carlsteel Engineering. This span has a timber deck, which was refurbished using timbers recovered from the demolished spans 1-4.

Spans 5 and 7 were wet blasted to Sa2.5, and an M24 paint system applied by Bagnalls, in a series of Saturday and weeknight rules of the route possessions of the Darlington – Bishop Auckland line.

Following the blasting, further cracking was identified in the bottom flange of the cast main beams. A supplementary planning consent for additional repairs to the listed structure was quickly agreed. These fractures, together with the known problems with the cross girders, were repaired using the Metalock stitch system.

The heritage of the site and structure were very much in the CML teams mind during the project. In addition to the use of recovered timber and masonry, the redundant lattice span 4 was donated to the Friends of the Stockton & Darlington Railway. Ross Chisholm explained that this is in store at the Weardale Railway but that they hope to use this as a training project for the next generation of tradespeople. Once restored it will be displayed within the Heritage Action Zone.

The opening of the completed bridge took place on 28 March, attended by 30 representatives from stakeholding groups. Despite their initial concerns at the scope of the works, the Friends of the Stockton & Darlington Railway complimented Network Rail and CML, describing the bridge as a “good job well done” and were very pleased to have been involved in the project.

Striving for Innovation: An industry challenge

27th September 2019

Creative thinking ideas brain innovation concept. Light bulb on yellow background

Signal engineers tend to have a measure of distrust when new ideas and concepts are put forward. This is understandable, given that any radical change to signalling practices can have catastrophic consequences if it all goes wrong and accidents occur.

It has taken over 20 years to develop and prove ERTMS/ETCS but, even now, the ultimate goal of Level 3 systems with no lineside signals and radio-based train detection seems many years away.

Nonetheless, progress has to be made with technology and engineering methods in order to drive down the cost of signalling, now measured by the terminology SEUs (Signalling Equivalent Units), a measurement based on the number of items controlled by the central interlocking.

Network Rail has had a Signalling Innovations Group (SIG) for a number of years and it holds a seminar annually to enlighten the railway community on the initiatives it is engaged in. Rail Engineer has reported on this event in the past, the last time being in 2014, so it was high time to take a re-look at what the group is currently engaged in and a meeting with the Group’s head, David Shipman, was held recently.

Group organisation and mission

Having national implications, SIG is part of the centralised engineering organisation within the IP Signalling project delivery organisation. The Group has a total of 18 engineering and support staff, based principally in Birmingham, Crewe and York but with outbased members in Glasgow, Derby, Milton Keynes and Reading. This will enable close contact with the soon-to-be-established Regional organisations, each of which will have its own signal engineers responsible for day to day performance.

Whilst much of the team’s work is an essential operational overhead, there was a budgeted programme of signalling innovations in Control Period 5 (CP5). For CP6, the group will work far more as an internal consultancy, winning the mandate for delivering specific packages of work. This has already borne fruit in establishing SIG as the deliverer of design tools elements of the research and development (R&D) programme for command, control and signalling (CCS).

Under the ‘putting passengers first’ devolution programme, SIG expects to become part of the national Network Services directorate, offering a key link between capital delivery in the regions and the central technical authority.

In line with the consultancy role and the need to maintain customer demand both internally and externally, SIG’s activities are regularly marketed by means of articles, external events and participation at national and international conferences. Interestingly, there is no one equivalent group in electrification & plant or building & civils, and only a smaller element in track, which perhaps demonstrates the complexities with which signal engineers are now faced.

Past success

A number of previous initiatives have come to fruition, others are still being taken forward:

‘Plug and play’ cabling.
This is a dreadful term, since it is anything but ‘play’, but it is now routinely applied to most signalling projects, mainly for the connection between trackside location and local devices such as signal heads and point machines. The idea allows much greater testing to be carried out in the factory, thus saving time. Lessons learned have shown, however, that the original intent to apply the plugs to long lineside cabling is inefficient, due mainly to the range of lengths that would need to be stocked for spares.

Product acceptance.
The often arduous process of getting new products accepted has been tackled head on by SIG. Equipment worthy of note, and now approved, includes the ElectroLogix interlocking developed by Atkins, now in use on the Shepperton Branch and in progress for the Norwich-Yarmouth-Lowestoft resignalling project; also the updated Ansaldo (now Hitachi) interlocking employed on the Ferriby to Gilberdyke project.

Aluminium cabling for power. The Class II lineside power supply for signalling systems now uses two-core instead of three-core cabling. This, in itself, saves a third of cable costs, but the adoption of aluminium instead of copper cores gives further reductions in price. SIG has been instrumental in achieving product acceptance for the many components and cables required.

Regional team assistance.
Getting track circuit re-set procedures in Manchester and a new design of theatre style route indicators for the recent resignalling at Liverpool Lime Street are examples where acceptance assistance has been given to regional teams.

Level crossing PLCs.
Some level crossings are now equipped with proprietary PLCs (Programmable Logic Controllers), thus reducing project cost. However, more work is needed to get a consistent set of requirements and to understand properly what is available in the commercial market. Being a tiny user in the vast quantities that are manufactured makes any special adaptations difficult.

Current projects

With the overall aim of reducing SEU costs by almost half, various innovations are underway, not always directly associated with signalling hardware and systems.

Tail Lamp Camera
This is a misnomer as the device is at the front of the train but hung on the tail lamp bracket. It incorporates a standard high-definition camera, is battery powered lasting up to six hours and is controlled using custom software developed for SIG. Pictures are taken at 25-50 frames per second with a GPS positioning reference incorporated. Greater positioning accuracy will increase the usefulness of the system for detailed design, and more work is planned on this element.
Originally envisaged for signalling needs, it is now extensively used for many asset-inspection purposes, for example saving around 5,000 site visits for the measurement of bridge parapet heights in the East Midlands.
Agreement has been reached with most TOCs for the camera to be put on any train, but with every journey being accompanied by an engineer who fits the appropriate camera for the purpose intended. This is normally a single forward-facing camera, but variants can include extra cameras viewing down to the track or out to the side. It is normal for images to be taken in both directions if double or quadruple track.
One of the ongoing challenges is transferring the images over existing network infrastructure owing to the file sizes involved.

Positioned Video Pixels – comparison of point cloud and video data.

Positioned Video Pixels
For signal sighting purposes, obtaining an accurate picture of the area where the signal is needed can be a fraught process. The old methodology of going to site with replica signal boards is long gone, but use of video and laser technology requires more development.
The latest result is a 4K ultra-high-definition video imagery and laser pointcloud system, three of which are now available, two mounted on maintenance vehicles, the other fitted as required to a Class 37 locomotive. The latter has permanent fixtures including power supply, cable looms and brackets to which a dual laser source can be attached. As part of the overall SIG service, an in-house train planner is also part of the team.
The resultant images enable signal sighting and its associated sign-off by many departments to be achieved off-site as it is capable of very accurate measurements. Laser data enhances the flexibility of video pictures. The signal engineer can position the signal where it is required and then assess this against other existing and proposed structures, such as OLE supports and gantries. Various assets can be inserted so as to visualise how the signalling will fit into the overall scheme.
All information is stored in a data model for the area or layout. The forthcoming Leeds to Manchester trans-Pennine upgrade will be using this modelling system. The images can be used for design, construction and access planning and can be downloaded to portable devices to assist trackside workers.

Signal-Sighting Form Tool (SSiLT)
It traditionally took significant amounts of time to generate a signal-sighting form and obtain all the necessary signatures. If an electronic form with electronic signatures were to be available, the time taken would be significantly reduced.
Such a system has thus been devised and is now a mandated format with records stored in one place. The system can be updated from other signal sighting methods through SIGs common data format, and a Signal Clearance Calculator interfaces with track geometry data to ensure the end result is not foul of the gauge.

The Headway Analysis Tool is a web-based solution that reads SDEF files generated from Sketch.

Headway Analysis Tool
Predicting future traffic flows and calculating the possible headways required to achieve the train service pattern is an interactive process. SIG has developed tools to optimise the process, commencing with the foreseen headway requirements and then inputting the train characteristics, such as length and speed, loading the given signalling system layout design and, finally, calculating whether it achieves the necessary results. If not, then a rework is required until an optimised solution is eventually achieved.

Design Automation

The digital railway and associated radio-based train control will require a new approach to signalling design if the SEU cost reduction is to be achieved. A design automation strategy is thus being devised that will deliver many principles of BIM (building information modelling) through a core data model that is stored, extended and shared through the project life.

A number of key steps are required to achieve this:

Step 1 – Asset Discovery.
Asset data is collected by various means from surveys and existing records, usually in different data formats and covering different disciplines – track, signalling, overhead electrification, power and suchlike. Workstreams are underway to integrate these accurately in order to obtain a complete record of survey data and to identify the assets from the images automatically. This will yield many benefits in safety, time and cost, but the result has to be 100 per cent accurate in order to eliminate inefficient human activity.
Step 2 – Scheme Design.
Automation will free up the designer to concentrate on the key issues that introduce risk to the proposals. As signalling, track and electrification design progresses, so the identification of problems, trade-offs, risks and cost can be analysed and changes made more effectively by automating time consuming repetitive aspects.
Step 3 – Design Review.
Having designed a new scheme based on an underlying model, interactive review can then take place, including simulated trains running through the layout to prove the effectiveness of the signalling. This enables better visualisation of the results and the changes that may be needed to obtain optimum performance.
Step 4 – Detailed Design.
At this stage, data needs to be shared with the supply chain, who can automate elements including signalling controls, power supplies and construction. Establishing data-exchange criteria will enable structured data to be provided during the bidding process and returned (in updated form) on project completion.
Step 5 – Construct and Test.
Ensuring that a project is built on a ‘right first time’ basis is crucial, as re-work costs money. The new approach for design tools can be extended to provide greater support during later project stages and, whilst ‘right first time’ is the ultimate aim, when problems do arise, they can be resolved with the best decision support available.
Step 6 – Whole Life Management.
Once commissioned, the project elements need to be integrated into all existing asset management systems.

It is estimated that the development of the core automated design process will take five years, and SIG is working to deliver this as part of Network Rail’s CP6 R&D provision. Data is at the heart of the process, with core software tools for visualisation and finalisation of scheme design supported by modular extensions for specific tasks. Currently, development is in the first year with the goal of having multiple ‘proofs of concept’ available so that the overall proposal can be demonstrated to stakeholders, including users, management and potential suppliers.

There is much work still to be done to achieve the end game of enabling automation tools built around a scalable core data model. With continuing devolvement of activities down to the new regions, a means of ensuring a universal commitment will be part of the challenge.

EULYNX

A European project that has existed for some time, EULYNX aims to specify and standardise the interfaces between electronic interlockings from different suppliers with the outside components of a signalling scheme, such as points, signal heads, axle counters, track circuits and so on, with the overall objective of facilitating equipment from different suppliers to be incorporated into the same project.

Achieving cross acceptance within 12 infrastructure organisations in Europe (Germany, Netherlands, Belgium, France, Luxembourg, Great Britain, Finland, Norway, Sweden, Slovenia, Switzerland and Italy) was never going to be a fast process, but members of SIG head up the assurance aspects and alignment of data structures. With meetings in a number of different European cities, it has the spin-off benefit of observing what other European railways are doing in the field of innovation.

SKETCH

Getting a signalling scheme plan right at the outset of a project is important and time consuming. Whilst computer aided design (CAD) techniques have been employed for some time, these have limitations in how they analyse the suitability of the plan for the eventual project.

Hitachi Information Control systems Europe (HICSE) implemented SIG’s requirements for a SKETCH tool that not only makes drawing of a scheme plan much easier but also allows many more elements from other disciplines to be included with sufficient intelligence to alert designers that the plan may have deficiencies. This is acknowledged as a first step toward automating the design production.

SIG will promote the system within Network Rail and the supply chain, as well as providing second line support and training of the design teams. A further article on how it all functions will be written for Rail Engineer later this year.

In closing, David Shipman was keen to stress that the above are all examples of how innovation in signalling has migrated to a different perspective and is now much more focussed on design challenges for a total railway solution. While previous work relating to new hardware or component elements will not be forgotten, it is less likely to produce the savings required to make signalling more cost efficient than the initiatives now being taken forward by the Signalling Innovation Group

Long may these continue.

Platforms from polystyrene? Who’d have thought it?

27th September 2019

MegaTech celebrates ten years of platforms with a difference

Next time you are standing on a station, waiting for a train, look down. Not at your feet – past those. What’s down there? On an older station it may be paving slabs, or tarmac. If it’s a newer platform, or a recent extension, it could be a fibreglass panel, or a concrete slab.

But what’s under that? Rubble fill retained by a brick wall under the platform coping stones? A complex arrangement of piled steel sections and cross braces with a glass-reinforced polymer (GRP) deck on top?

If it was built in the last ten years, it could even be a block of expanded polystyrene. You know, the stuff that TVs come packed in when they are delivered in a box.

It seems an unlikely material to use for station platforms, but, actually, it’s a good choice – easy to install and simple to modify.

An idea

It all started over ten years ago. A chartered surveyor named George Rowe saw expanded polystyrene being used to fill voids under platforms in the Netherlands, and thought it was a great idea.

Up to then, George had been leading a double life. He joined Tarmac Major Projects in 1986 as a trainee quantity surveyor. Working first at the Faslane naval submarine base on the Clyde, and then at the Royal Naval Armaments Depot at Coulport, he had been spending one month in three at college in Croydon, where Tarmac trainees from all over the country gathered centrally for the academic part of their training.

At the same time, George was a semi-professional footballer. He trained with local clubs wherever he was working around the country, but at weekends he was back in Scotland, playing for Clydebank, Queen of the South, Arbroath, Stirling Albion and finally Partick Thistle. While at Queen of the South, George also spent 18 months as the player/manager, being the youngest league manager in Britain at the age of 29.

By this time, George had left Tarmac and was working as commercial director with railway contractor QTS.

When he saw the Dutch platform, George thought that the simple idea could have applications in the UK, which was just embarking on a programme of renewing and extending station platforms as new, longer trains started to come into service.

He spoke with the Dutch supplier, intending to use that company as a source both of technology and of material. However, when he approached Network Rail, he had a setback as the material wasn’t acceptable in the UK, so he had to re-engineer the whole product.

Improved technology

Expanded polystyrene (EPS) is naturally flammable, self-igniting at a temperature of about 450°C. However, additives such as hexabromocyclododecane (HBCD) give the foam flame-retardant qualities such that the material shrinks away from a flame and self-extinguishes when the source of the fire is removed.

The large blocks of EPS used for building platforms need to be protected from the weather and accidental damage. The original Dutch system used sheets of polyurea, bonded to the outer surfaces of the blocks. That also has a flash point of around 450°C and is self-extinguishing.

However, at Network Rail’s request, George sought out another material, finally selecting sheets of a cementitious material that both met the technical specifications and gave the product the appearance of cement, so fitting in with existing and surrounding structures.

Tests were carried out by Exova Warringtonfire, demonstrating that the new product complied with Network Rail’s standards.

Once the tests were completed to the satisfaction of all Network Rail Departments, including James Holland, Network Rail’s principal fire safety specialist, George’s new company MegaTech Projects was ready to take on its first real-world challenge.

Three stations on the East Grinstead line were to have platform extensions. Geoffrey Osborne was the chosen contractor and three different solutions were chosen. Oxted itself was to be extended using traditional techniques – a brick retaining wall with a rubble infill behind.

Upper Warlingham was fitted with a GRP deck, supported by a steel framework that had been piled into the ground.

Sanderstead suffered from poor ground conditions, so it was the natural choice for MegaTech’s new lightweight system. A 50mm sand screed was laid and the EPS blocks placed on top. These were topped off with a polythene membrane and the concrete slab.

Network Rail’s lighting, CCTV and long-line public address requirements were all incorporated into the precast slabs. Coping stones and a tactile strip were fitted and the platform finished off and lined out.

And that, as they say, was how it all began.

The first installation – at Sanderstead.

Supply chain

The experience of successfully delivering Sanderstead enabled George and the MegaTech team to fine-tune the design and to establish their supply chain.

Adams Design Associates of Hastings became MegaTech’s sole designer, sorting out not only the design of the finished platform but how the various components fit together. The EPS blocks and the concrete slabs have to overlap so that no two joins coincide. Some blocks are channelled to accept cables, or drainage, in which case manholes need to be left in the concrete slabs.

The EPS blocks, cut to size and with channels, holes and recesses in them to the Adams design, are supplied by DS Smith of Livingston, West Lothian.

Peter Duffy, a civil engineering and construction company in Wakefield, takes those blocks and finishes them off. The cementitious board, delivered from Warrington, has to be fixed to exposed faces – normally three sides on end blocks and two sides (front and back) for those in the middle. In addition, recesses, such as chambers under manhole covers and cable/drainage channels, have to be clad as well.

Interestingly, about ten millimetres of EPS is left exposed, sticking up above the cladding. This is the compression allowance, to give room for the block to be slightly crushed as several tonnes of concrete slab is placed on top, without it damaging or cracking the cladding.

Those concrete slabs come from FP McCann. Originally, they were ‘just’ platform surface slabs – the copers and tactiles had to be added. Now those are all cast-in too, though tactile strips from Viztek are still used on occasion.

The slabs also have an anti-slip finish and are thicker at the front than the back – the slope of between 1:40 and 1:80 encourages drainage towards the rear of the platform and again complies with Network Rail’s standard requirements.

While the civils plant on site is usually supplied by the contractor, MegaTech likes to use road-rail (RRV) plant from Readypower, as its drivers know the system and how it fits together.

In addition to Duffy, GK Railways, CSM Projects and Rainton Construction (Scotland) build the platforms and extensions on site. Hayward Contracts manufactures, supplies and erects all of the fencing and Wrightseal seals all of the exposed edges and joints. Even the job of lining-out the completed platform is entrusted to only one supplier, Lincs Lining from Lincoln.

Bath Spa

Ask George what his most memorable job is, and he has several definitions of the word ‘memorable’.

One of the largest was at Bath Spa station, in amongst the World Heritage Site that is the city of Bath. Electrification was coming through, and there is a minimum distance allowable between the overhead wires and the edge of the platform canopy. At Bath, this would have been below the minimum and, at any other stations, the canopies would have been modified and cut back.

But not at World Heritage Bath.

Fortunately, however, Isambard Kingdom Brunel originally built the line using his broad gauge of seven feet (2,134mm). When the route was converted to standard 4’ 8.1/2” gauge (1,435mm) in 1892, having been dual-gauge since 1874, this left the two tracks ten feet apart rather than the usual six.

So, the plan was to move both the tracks and the platform edges closer together, while leaving the canopies in their original location. This would give extra clearance between the canopies and the overhead wire, now above the moved tracks.

One platform was to be modified at a time, leaving the other platform open so that a revised train service could operate, with trains between Bristol Temple Meads and London Paddington via Bath and Chippenham operating every hour.

The speed with which the MegaTech platforms could be erected was key to it all working.

Main contractor Hochtief asked MegaTech to handle all of the platform work, including lifting the original surface. This was a mix of Victorian paving slabs and tarmac. The plan was to lift and reuse as many of the Victorian slabs as possible, so that, when the new, wider platform surface went back down, it would be similar in appearance to the original.

On the weekend of 8-9 April 2017, Babcock removed the track adjacent to Platform 1. MegaTech moved in on Monday morning, stripped the platform surface, broke up the old platform underpinnings, laid the sand bed, positioned the EPS blocks, replaced the retaining wall so it would closely resemble the original and relayed the surface using as many old slabs as possible.

That was all finished on Friday night. That Saturday, Babcock replaced the track, then removed the railway next to Platform 2 on Sunday, which was Easter Day.

Bath Spa – one patfiorm completed, the other is work in progress.

Monday to Friday was a repeat of the first week. Babcock replaced the track on Saturday, Sunday was spent tidying up and commissioning, and the whole station reopened with new, wider platforms, which were now at the standardised height of 905mm above the track and 740mm from it, on Monday morning. What’s more, the new OLE wires, when they were installed, would be the regulation distance from the untouched canopies.

Uckfield

One property of EPS that is not normally needed when building a station platform is that it floats. However, at a station such as Uckfield in East Sussex, which regularly floods above the platform height, that could be a problem. What would happen if the natural buoyancy of the EPS was more than the weight of the concrete platform slabs? Would the whole thing just float away?

MegaTech’s designers and installers had an answer to that. For a change, they didn’t butt the EPS blocks up against one another – they left a gap, facing all four sides of each one. This allowed the floodwaters to pass through the platform and reduced the total amount of (buoyant) EPS. The concrete slab was also thickened into ribs that fitted down into the gaps, both locking the blocks in place and adding weight.

Finally, Platipus ground anchors were driven through the platform surface slab, passing down through the gaps and three metres into the ground, locking the assembly in place. It wasn’t going to go anywhere!

Uckfield – installing a Platipus anchor.

Short access times

One of the two platforms at South Hampstead station, between London Euston and Watford, had suffered from retaining wall heave in 2013. This pushed the footings out and forced Network Rail to close half of the platform, only using the other half.

With the added complication of a high-voltage cable running through the platform, and work access limited to only two hours each night, with no time available at weekends, that half of the platform stood unused for two years.

Half of the platform at South Hampstead had been unused for two years.

Finally, J Murphy & Sons was brought in to rebuild it, and MegaTech was asked to undertake the platform work using its EPS system.

The first task was to demolish the damaged platform and survey the footings. These contained cast-in concrete ribs that, although they could be cut back by hand, couldn’t easily be removed entirely. The solution was to cut the EPS blocks to fit, and cast the concrete slabs to fit them. This resulted in 26 slabs – every one of which was different.

The blocks and slabs were prepared in a Murphy compound nearby, then brought to site in the correct order. The platform was rebuilt between late-January and April 2015, a three-month period that only allowed a total of 45 hours of access – on one night it was just 50 minutes.

Access was also a problem at Newark Northgate, this time it was just six hours a week, all on a Saturday night. A timber 28-metre platform was to be extended by 38 metres. As the existing timber trestle was in poor condition, MegaTech and principal contractor Carillion were asked to replace the whole thing. However, the train operator required at least 28 metres of platform, an equivalent length to the original structure, to be available at all times.

To achieve this, work was planned in three six-hour possessions over three weekends. Every section had to be complete at the end of the shift so as to comply with the train operator’s requirements.

Watford Junction was another station with an old wooden platform – Platform 11. It was replaced over Christmas, with the last train calling late on Christmas Eve and the first train using the new platform on the morning of 27 December, just 54 hours later.

All of this is a far cry from building a new station, as MegaTech did for VolkerFitzpatrick at Cambridge North. 1,000 metres of new platform on virgin ground – a doddle!

Success breeds success

One of the more successful results of a MegaTech platform extension came at Slough. Working to an overall design by Amey Consulting, MegaTech was asked to extend two platforms, one by 100 metres and one by 70 metres, which it did in 36 hours.

The visible speed and success at Slough meant Network Rail’s response was to cancel the partially completed, traditional design at Maidenhead station (in March) and have it reissued, specifying the MegaTech EPS. Amey Consulting worked with Adams Design Associates to rework the design. Installation commenced in August and was complete by September, more or less when it was originally required. Network Rail had clawed the overrun back.

It’s a cracker

But ask George Rowe what the best project that MegaTech has completed is, and his answer is surprising – Ulceby station rework, Saturday 7 September 2019, for a fee of just £10,000.

Ulceby – using an excavator to push the slab forward into position.

Really?

MegaTech had extended Ulceby, which lies on the Barton line in Lincolnshire and is served by trains between Cleethorpes to Barton-on-Humber via Grimsby and Immingham, in 2015 as part of Siemens Mobility’s North Lincolnshire resignalling and control project.

The platform extension was completed as planned. However, the railway line through Ulceby was undulating, and the extension followed that line (905mm high and 740mm from the track).

A couple of years later, Network Rail upgraded the track, smoothing out the undulations and slewing it over, which now made the EPS platform too low (by up to 60mm) and too far from the track by 30mm. To conform to standards, it had to be moved outwards and raised up.

Using any other system, the whole platform surface would have to come off, the underpinnings modified, and then the surface reinstated, a major job.

Ulceby – lifting the patform surface using bottle jacks.

Instead, MegaTech did it in one evening with an excavator and four bottle jacks.

First, the excavator got behind each concrete platform slab and gave it a shove, moving it out 30mm.

Then, using the bottle jacks, each slab was raised up by about 70mm. A spacer of the correct thickness, already faced by the cementitious material, was then slid into the gap and the slab lowered. Job done.

It was quick, easy, cheap, and really demonstrated the versatility of the MegaTech EPS system.

It was also almost exactly ten years since MegaTech installed that first platform extension at Sanderstead.

Happy Birthday, MegaTech!