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Sunday, July 21, 2024

Perfect platforms

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Recent harsh winters have resulted in station platforms taking a beating from the effects of rain, snow and ice.

Some of the worst damage has occurred where the platforms have suffered from the effects of frost heave. This is caused when rain water penetrates into the compacted fill inside the platform and subsequently freezes, expanding as it does so and pushing outwards on the structure of the platform. This can impose stress on the platform surface and the riser wall, and the resulting damage can cause dangerously uneven surfaces and weakened structures.

Problems at Perth

A recent project at Perth station arose for this very reason. As well as repairing the damage, Story Contracting was asked to design and build a solution to frost heave. Several measures were taken to help ensure the platform’s long term resistance to future problems, including careful selection of frost resistant aggregates and construction details.

One example is that, over time, the joints around the edges of tactile pavers can offer a potential route for water ingress. To overcome this, the design at Perth station completely eliminated the need for tactile pavers and instead included tarmac surfacing laid all the way up to the back of the coper where a good seal was created. Then, to provide tactile feedback behind the coper, an array of studs was resin anchored permanently into the surfacing. These were positioned using a bespoke rig that drilled multiple holes at once, all correctly laid out into the standard offset pattern.

These measures have helped ensure that Perth’s platforms are well equipped for whatever the upcoming winters have to offer.

Bridging Birkenhead

Birkenhead Central station has recently had both of its platforms refurbished, also by Story Contracting. This proved to be a particularly challenging project, largely owing to its location as the station is situated in a cutting with tunnels at both ends and no direct road access. However, with a large fleet of road-rail plant, Story Contracting was well placed to get materials in and out of the station – although even this wasn’t as simple as it might have been.

The nearest road rail-access point was more than a mile away at the Arthur Street depot. Taking account of travel time along the track, this meant that there was little more than two hours of working time that could be achieved each night in the short maintenance possessions that were available.

This would clearly lead to significant cost and risk to the programme. To combat this, arrangements were made to take permanent possession of a redundant siding within the station. This enabled Story to leave the RRV and its trailers on track permanently, removing the need to on-track the plant every night and eliminating the journey time from Arthur Street. To supplement this, as much new material as possible was lowered directly into the site by crane from the adjacent gas works over a seven metre high wall.

On the platforms, Section D notices were used to reduce the operational lengths so that work could progress alongside normal use of the station. The initial phase of works shortened the platforms furthest away from the station building and caused the least disruption to passengers and staff. The second phase, however, closed the platform at the station building end and also took the existing footbridge out of use so that it could be refurbished.

For this closure, a new access to the station had to be created. This used a link bridge leading to road level that spanned off a temporary Birkenhead temporary footbridge in process of construction [online]footbridge which was built to join platforms 1 and 2. This segregated the work site from passengers, safeguarding the continued operation of the station.

However, even this solution imposed numerous design considerations. Signal sighting was factored in to ensure that train drivers sight lines were not obscured and the minimum platform lengths that had to be maintained for trains dictated the location of the footbridge. The orientation of the staircases was designed so that passengers arrived directly onto a platform and not a worksite.

In addition, the footbridge then had to meet Network Rail standards for safe clearance for trains, and the staircases needed to be DDA compliant. The footbridge also had to be fully boarded out to prevent items falling onto the track. This then meant that lighting and security systems were required so that the footbridge could be monitored.

The loadings that this temporary structure would then impose on the platform meant that a foundation design was needed to ensure that its mass was sufficiently spread.

With the temporary footbridge opened, the existing footbridge was refurbished with steelwork repairs and the replacement of missing rivets. It was also partly re- roofed and given a full redecoration inside and out, along with DDA compliant staircase treads and nosings. A new anti- skid surface was installed throughout to complete the works.

Story Contracting’s site teams struck up excellent working relationships with the station staff which was essential due to the potentially disruptive nature of the works. This allowed the teams to maintain communication allowing plans to be agreed and put in place in good time.

Long ramp at Long Eaton

The Access for All Programme is part of the Railways for All strategy that was launched by Network Rail in 2006. Its purpose was to address the issues faced by passengers who were using the railway stations in Great Britain be it the disabled, elderly, mothers with pushchairs or simply people with heavy luggage!

Long Eaton station is built at high level on top of an embankment that was originally accessed using some steeply sloping ramps. Story Contracting completed an Access for All project to design and build two lifts from ground to platform level. The new lifts were at the foot of the embankment slope and used link bridges to cross to the platforms.

The station remained open throughout and a fully DDA-compliant temporary disabled access ramp was installed. This was constructed from scaffolding and, in order to create a gentle slope from platform level down to the car park, was more than 30 metres long. In addition to a non-slip surface it was fully lit, had 24hr CCTV surveillance and all necessary landings and handrails to comply with statutory requirements.

The new lift shafts used piled foundations that were complex to build because of the limited site access that was available. This restricted the size of the piling rig that could be used, not to mention that the site was on an embankment adjacent to a live railway line accompanied by poor and variable ground conditions including boulders, cobbles and running sand all encountered within the small building footprint.

To overcome these challenges, Story Contracting’s design achieved a watertight structure using a combination of contiguous piled retaining walls internally lined with reinforced concrete that was tanked to create a dry pit and shaft ready for the installation of the new lift.

The task of constructing two new lift shafts and associated link bridges in a busy operational station was always going to be a test but all went smoothly due to detailed planning. Train operators, Network Rail and local stakeholders such as Erewash Council and Derbyshire County Council were all fully consulted.

Key lifting activities were undertaken during night shifts utilising possessions and local road closures. Structural steelwork elements for the shaft and walkways were designed to be prefabricated and painted off site and delivered pre-assembled and ready for installation. This meant that all lifts could be successfully completed in short five hour possessions.

The works were all completed on programme and budget and the result is that Long Eaton station now benefits from step free access to each of its platforms.

Long Eaton is one of a number of stations that have been refurbished by Story Contrac- ting, other recent projects being at Glossop, Whaley Bridge, and Roman Bridge in Wales.

Station works are a core part of keeping our rail networks running smoothly and efficiently. Whilst the great British weather remains ever unpredictable, the need for quality service across our infrastructure will remain. Keeping up with this demand will continue to be an important role for companies such as Story Contracting.


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