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Platforms from polystyrene? Who’d have thought it?

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.

Cambridge North.

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.

Widening the platform at Bath Spa.

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?

Uckfield – gaps were left between each block so that floodwater could flow more easily.

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!

Nigel Wordsworth BSc(Hons) MCIJ
Nigel Wordsworth BSc(Hons) MCIJhttps://www.railengineer.co.uk
SPECIALIST AREAS Rolling stock, mechanical equipment, project reports, executive interviewsNigel Wordsworth graduated with an honours degree in Mechanical Engineering from Nottingham University, after which he joined the American aerospace and industrial fastener group SPS Technologies. After a short time at the research laboratories in Pennsylvania, USA, Nigel became responsible for applications engineering to industry in the UK and Western Europe. At this time he advised on various engineering projects, from Formula 1 to machine tools, including a particularly problematic area of bogie design for the HST. A move to the power generation and offshore oil supply sector followed as Nigel became director of Entwistle-Sandiacre, a subsidiary of the Australian-owned group Aurora plc. At the same time, Nigel spent ten years as a Technical Commissioner with the RAC Motor Sports Association, responsible for drafting and enforcing technical regulations for national and international motor racing series. Joining Rail Engineer in 2008, Nigel’s first assignment was a report on new three-dimensional mobile mapping and surveying equipment, swiftly followed by a look at vegetation control machinery. He continues to write on a variety of topics for most issues.

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