Raising the roof in Adamstown

Architect BDP Ireland wanted to create a dramatic roof for the recently completed railway station on the main Cork-Dublin train line – part of a new town development at Adamstown, near Lucan, Dublin. The practice designed a spaceframe structure for the 1100m2 , 37.5-tonne steel roof.

Matt Green, project architect, explains that because the team could only work on the station side, they chose to build the roof on the ground and lift it into place. To achieve this, BDP appointed specialist contractor Mero UK. Green and Brian Linton, head of engineering at Mero UK, explain how they work together.

Q: What was your original vision?

A: Green: We wanted to create an iconic building, because the railway station is part of a large scheme that includes a housing development. The roof has the shape of an airship or a diamond. We also needed to create a roof structure that could be built on the ground and lifted over the tracks. We felt that a spaceframe was the best option.

Q: Why did you choose Mero UK?

A: Green: We were advised that Mero was the leader for spaceframe roofs. Our first contact was at the tendering stage. We were impressed with the quality of the products they were offering and their professionalism.

Q: What were your first thoughts when BDP presented its drawing to you?

A: Linton: Mero UK developed spaceframe in the 1960s and has worked on schemes such as the Eden project in Cornwall and stadiums requiring massive structures. We knew we could achieve the shape they designed. We’re familiar with assembling the components in a large structure without manipulating the frame. With spaceframe, all geometries can be realised.

Q: What special requirements were there?

A: Linton: The nature of the structure meant it had to be built alongside the railway tracks, not on top of it. We had two options to lift the structure: to create it in two halves and stitch in the middle, or build it as one piece. Because of the time constraint, we decided on the second option.

Q: How did you develop the design?

A: Green: We started work at the beginning of this year. At the first meeting, Mero came up with precise preliminary drawings and calculations. After that, we communicated through emails and met in Ireland and London. It worked very well. We discussed the support points and elements requiring specific structural engineering work.

A: Linton: We worked with a specialist software company based in Germany during the manufacturing process, enabling us to get precision to within millimetres.

Q: How did you build the roof?

A: Linton: The frame comprises cast steel nodes with threaded holes at varying angles, into which steel tubes are screwed. When connected, they form a lattice structure. The on-site construction took eight days.

Q: What were the construction challenges?

A: Linton: We had to make sure that all the cables and elements were perfect. During the construction, we found there had been complications with the fabrication of certain items. They had to be adjusted on site to make sure they fitted. The critical items had to be identified, recertified and retested.

Q: How did the lift go?

A: Linton: We weren’t sure we could find a crane with a 30m high reaching capacity in Ireland, but we did. We started lifting the roof at midnight and it was in place when the station reopened at 4.30am. The most vital aspect of the lift was that the slings and chains coming from the frame to the hood of the 500-tonne crane had to be exactly the same angle as the lifting eyes. If not, there was a danger that the eyes would break under the load and the 37.5 tonnes of steel would fall to the ground.

Q: What was the impact of value engineering on the specification?

A: Green: At the tender stage Mero’s proposal was so detailed there was almost nothing to change, so there wasn’t any particular value engineering.

Q: What do you think of the finished result?

A: Green: We’ve built a very good relationship with the contractor. I am very impressed with the result. It looks as good, if not better than we originally designed it.