Thirty-five experts from Unger Steel Group used Tekla’s BIM software to plan, produce and assemble the diamond trusses of the partially transparent roof of the Vienna Central Railway Station. Now when the trains arrive at the station, passengers see the first glimpse of the city through the roof.
The new Vienna Central Railway Station is a major European traffic hub. When completed in 2015, about 145,000 passengers and 1,000 trains will pass through the station every day. The project has an attached shopping mall, residential buildings and park. Unger Steel Group had to work with precision on this crowded site and include other project parties.
Unger was contracted to complete the roof which covers the tracks, with a complex geometry of 14 unique diamond-shaped steel trusses. It used Tekla software and Trimble Total Station to complete the work.
What’s in the model?
Tekla created constructable steel structures, modelled and detailed the main structure and substructures like cable channels, extracted data and drawings for production and assembly, and simulated welding sequences of the complex components.
Up to ten designers worked on the model in multi-user mode. Unger imported the architect’s model as 3D DWG files to Tekla Structures for design and detailing the diamond trusses. As numerous parties operated on the huge construction site, Unger included platforms with rails and concrete foundations to the model in order to notice and solve possible clashes in the design phase.
At Unger BIM does not stop at the design office door. The company configures each new version of Tekla Structures according to specific standards, which enables it to plan specifically for cutting and production.
Unger created transport lists and surveys directly from the model in Tekla and used it to control production and assembly.
The required data is transferred directly from the design office in to the DSTV file format and interfaces with the cutting machines in Unger’s workshop. The process means production can start immediately after completion of planning. Transferring fabrication information automatically to production machinery means errors are avoided.
Unger chose Tekla because it had to work punctually: it was crucial to have the right material at the right place.
Unger’s team had to assemble the complex diamond trusses in a very limited space. The pieces arrived to site just before they were bolted together. The site staff assembled the first trusses while the workshop team produced the remaining ones. The entire process from cutting one truss to its final assembly took on average three and a half months.
Trimble Total Station
Unger used Trimble Total Station with Tekla for the first time to assemble the diamond trusses. Unger assembled the roof components while they hung from a crane, and the team needed exact position information for lifting and fitting the components correctly at 15m above the platforms.
They used the combination of Tekla and Trimble in a preassembly workshop to measure the components after welding, to spot possible manufacturing tolerances before assembly, and later to control the position of the structure and put the parts together.
From Total Station to Tekla and back
The workflow for positioning the roof parts moved in rounds. Unger’s team measured the structure with Trimble Total Station, imported the data to Tekla Structures, adjusted it, and exported the modified data back to Total Station for positioning.
As any inaccuracies would have affected the composition, the Unger team performed control measurements continuously in case the components would carry tolerances from fabrication or transport. On the connection points of the diamond trusses, the team measured the structure, downloaded the measurements into the Tekla model and after this planned and manufactured the connection parts. On site, they also marked building axes with Trimble Total Station.
Time, money and workflow
Smooth workflow between office and site is the goal of every construction company, and according to Unger, Trimble and Tekla together take their customers closer to this goal.
BIM and automated data transfer accelerated the project. With Trimble Total Station, Unger’s own staff could measure the structures to save on expenses of external surveyors. They transferred the measurements of the built structure directly to Tekla to save time and labour and avoid entering the measuring data manually. Tekla eased the logistical challenge with automatically generated transport lists and aid in controlling production and assembly sequence.
Collaboration using Tekla BIMsight
Unger chose Tekla BIMsight for collaboration with architects and structural engineers. Each party had the building information model available and could work together, including production and installation teams on site. Tekla BIMsight was also used for the approval process in the planning phase.