Barrett Byrd Associates

Building a new visitor centre on the top of Mount Snowdon required a complete trial erection of the structure, to make sure everything fitted together, before construction actually started on the sometimes inclement summit. Martin Cooper reports on the UK’s highest construction site.

Occasional dense fog, intermittent low cloud and winds that can regularly reach speeds of 80mph are just some of the conditions that had to be overcome by the team building the new Mount Snowdon Visitor Centre.

And, aside from the unpredictable weather, the contractors were also faced with the logistical problem of how to get materials and workers to a construction site 1,065m above sea level.

Conveniently Snowdon has a mountain railway which winds its way to the summit and this provided the contractors with a viable transport route to the top. All of the materials including steelwork were bundled into 14m-long packages to fit onto a rail flat bed carriage.

Once materials were on-site the construction team were very much at the mercy of the elements. “It can be a bright sunny day at the bottom, but windy and raining at the summit,” says Andrew Roberts Project Manager of steelwork contractor EvadX. “The weather is extremely changeable.

“When we started erecting the steelwork it was early Summer, but we still had to work through all weather conditions. Taking all the challenges into consideration I’m proud to say we erected the entire steel frame in just over two months.”

Wind speed has also been a major factor, as the train service is halted when velocity exceeds 40mph, and on the occasions this happened all work had to be cancelled for the day.

“We had some close calls, but luckily the train service wasn’t halted while our workers were still on the summit,” says Mr Roberts. “It’s a long walk down Snowdon.”

As of November the steel frame of the visitor centre is complete, the roof has been erected and fitting out has begun. Main contractor Carillion - weather permitting - hopes to carry on working until Xmas, and then resume work in early spring to complete the job by Easter 2008. The aim is to seal the structure before the winter sets in. The Visitor Centre is then scheduled to open during the summer of 2008.

“Considering the logistical challenge of working on the highest point in England and Wales we are still pretty much on schedule,” explains Brian Hanlon, Carillion’s Project Manager.

‘If we get a mild winter we may be able to work right through and get ahead of schedule. But the train service is also stopped if there is ice on the tracks, so again it’s all weather permitting.”

Work on the project effectively began in early 2006 with the demolition of an existing Snowdon visitor centre. Once the ground was cleared the concrete foundations were also installed to allow EvadX to begin its steel erection programme this April.

The finished visitor centre will consist of a large cafe with washrooms and information area, medical facilities and an emergency overnight shelter. Attached to the centre there will be a 60m-long steel framed lean-to structure which will house a new platform for the railway, plant rooms and staff accommodation.

Building a structure on mountain top is a one off and the construction team decided early on in the design stage that a complete trial erection of the structure would be needed.

“The remoteness of the location dictated this,” explains Mr Hanlon. “It was no good fabricating the steel and then transporting it to site to then discover we needed some alterations.”

The trial was carried out at Corus’ Deeside facility at Shotton. “We marked up all of the individual members which then helped with the second erection on the summit and also ensured the steel was taken up the mountain in the correct order,” explains Mr Roberts.

The trial erection consisted of putting up the complete steel skeleton of the structure as well as the roof which was a Corus supplied Hi-Point roofing system.

The roof manufactured at the Corus Building Systems’ facility in St Helens was delivered to Shotton in 35 individual elements which were then trial erected to make sure they fitted with the main steel structure.

“The roofing system and the steel frame both lend themselves to off-site construction,” comments Mr Roberts. “With no room to store materials on-site this method of construction was crucial to a successful completion of the job.”

Once the trial was over the pre-assembled roofing elements were stored and when the time came they were simply transported to site and erected on top of the frame.

“Steel is easy to erect and I can’t imagine trying to build this structure with any other material,” comments Mr Hanlon. “The trial erection proved beyond doubt that the real construction programme was going to be successful.”

Once the erection programme began in earnest it was divided into three main phases and all steel taken to the summit was usually erected that day to minimise disruption to other trades.

EvadX used two cherrypickers for the erection and one 8t capacity mini mobile crane. The cherrypickers were fortunately just small enough to squeeze onto the train’s flat bed trailer, while the crane was specially sourced as the largest crane available which could be transported by rail to the summit.

According to the design team the main structure, which measures 30m-long x 13.5m wide, was complex to fabricate and design because of its unusual sloping shape. The slope of the structure is intended to fit into the mountain’s summit environment without impairing the spectacular view.

Four columns at the front and back all slope out at 13-degrees, while the curved ends of the structure feature column members which slope inwards and outwards. To achieve the sloping roof the back columns are 5.5m high, while those at the front are only 3m.

These columns are all stainless steel CHS sections and Mr Roberts says they are ‘architectural features’ and will be visible from inside the finished building. The columns will also be incorporated into large glazed areas which will allow tourists to see right through the building.

In order to erect the complex shape on what is a very confined site, EvadX initially constructed one square section. “We then proppped it up and using this as a support we then erected one curved end around this. Once this was up we were able to take the temporary props down and erect the rest of the structure in the same way,” sums up Mr Roberts.

Fact File
Mount Snowdon Visitor Centre, north Wales.
Client: Snowdonia National Park Authority
Architect: RH Architects
Structural engineer: Arup
Main contractor: Carillion
Steelwork contractor: EvadX
Steel tonnage: 120t

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