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A model solution

Building information modelling has cut costs and improved efficiency on a Swedish rail project.

Fast track

Fast track: The new tunnel will increase railway capacity from four to 24 trains per hour

The construction of a railway tunnel through the Hallandsås ridge in southern Sweden has a long history, but the end is in sight, with the start of traffic services scheduled for late 2015. To help meet the demanding project schedule and the challenge of excavating the tunnel while doing detailed design, the Swedish transport administration Trafikverket has been using building information modelling (BIM).

Consultant Sweco is responsible for the project’s BIM strategy and coordination, which includes helping the project team implement effective processes to optimise production, develop integrated 3D models, and use that information throughout the project lifecycle.

And by implementing BIM successfully on this project, the team has been able to use some innovative methods, re-use resources, reduce costs and improve productivity.

The most important contribution is our coordination process, which efficiently reduces design errors and increases quality

When completed, the SEK 700M (£64M) tunnel will increase railway capacity from four to 24 trains per hour. Construction originally began in 1992, but stopped five years later due to concerns over its environmental impact. The project restarted in 2003, with new tunnelling techniques and equipment enabling a fully lined, watertight tunnel to be built to minimise the ­environmental impact.

Trafikverket set a challenging timetable for the project, so planning and detailed design for the tracks and rail infrastructure had to happen in parallel with the tunnelling. Adopting BIM was intended to help this process, ­according to Trafikverket technology strategist for major projects Leif Malm.

“Trafikverket have been using BIM techniques and methods since 1994 for its rail projects but concluded that increasing its level of BIM adoption would help improve productivity and reduce rework on the Hallandsås project,” he explains.

3D-object library

Sweco worked with Trafikverket to create an integrated 3D-object library, as well as automated scripts for when objects are inserted into the CAD models.

Every object is specified with detailed information such as type, codes, part number, description, and web links. This standardised library means that every 3D object can be re-used by Trafikverket on future projects.

The 3D model allows visualisation of design and function, as well as automatically generating drawings and reports, facilitating simulation and analysis, and aiding in the identification and avoidance of clashes.

Both Trafikverket and Sweco were familiar with Bentley’s software, and saw it as a natural choice for the Hallandsås project, using the company’s ProjectWise, MicroStation, InRoads, Rail Track, and Navigator for different aspects of the job. Bentley Navigator is used to visualise and inspect the 3D digital model, while ProjectWise is the hub for document management and administration.

As tunnelling proceeds, by feeding as-built data from the tunnelling into the 3D model, integrating it with the latest design and engineering information, the team can effectively manage the changing conditions.
This shared information enables the design engineers to analyse the effect of, and react to, changes immediately, avoiding the risk of costly surprises during the construction.

“We call that ‘live BIM’ - to use information from the ongoing production as a basis for impact assessments and adjustment of the engineering,” explains Sweco BIM strategist and team manager Daniel Ahnsjö.

“The most important contribution is our coordination process, which efficiently reduces design errors and increases quality,” he says, adding that checking design files using Navigator’s clash detection functionality highlights design problems and obvious errors, something that has saved the project around £4.6M.

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