IFC models shortened the design time of Nelostie bridges by months

The renewal of Finnish national road 4, AKA Nelostie, from Kirri in Jyväskylä to Tikkakoski has been one of the largest and most advanced infrastructure projects in recent years. The new highway, which has been awarded a Tekla BIM award, includes 30 bridges, the design time of which was shortened by several months with the help of a digital process.

Finland’s longest highway, Nelostie, is one of the country’s most important main roads for heavy traffic, stretching from Helsinki in the south coast all the way to Utsjoki in the northern border. The service level and safety of an approximately 16-kilometre section of Nelostie in Central Finland is currently being improved in the Finnish Transport Infrastructure Agency’s Vt 4 Kirri–Tikkakoski project. “This is a major project for us, the largest one in progress at the moment,” says Project Manager Jaakko Taipale from the main contractor of the project, Destia.

Pioneering information modelling eliminated work stages and saved materials

What makes the Kirri–Tikkakoksi infrastructure project truly special is the pioneering information modelling utilised in it. At the request of the Finnish Transport Infrastructure Agency, the design, implementation and quality control of the project were carried out based on information models. The different parties of the project were provided with up-to-date and reliable information with IFC models, almost completely eliminating the need for 2D drawings. “These new tools provide us with a better understanding of the structure and eliminate unnecessary work,” Taipale summarises.

Thanks to these new tools, the highway was opened to traffic approximately 8 months ahead of schedule, and the design time of the bridges was shortened by about six months. “We saved a lot of time in the planning, when the external inspection of the plans and the approval of the Finnish Transport Infrastructure Agency were handled directly from the data model,” says Project Manager Mauri Kuvaja from Sweco. Usually, external checks are carried out on paper drawings. In addition, the models also helped optimise material consumption. “Concrete consumption was reduced by 11%, meaning over 1,000 cubic metres.”

The information models were also utilised at the worksites, allowing e.g. steel fitters to examine models of the bridges’ steel reinforcements via a large touchscreen inside the site hut. “At the start of the project, we provided the entire project team with training on information modelling,” says the principal designer of the bridges, Juha Litmanen from Sweco. The information models provided dimension and location data at the worksite and for the steel reinforcement plant. “This was a first in a Finnish bridge project. We managed to eliminate unnecessary work stages, and there wasn’t a single mistake in the steel reinforcement deliveries.”

The project also involved creating bridge maintenance models for Nelostie, allowing the new operating methods to provide added value for bridge maintenance as well. “The project proved the benefits of information modelling in practice, which I believe will promote the digitalisation of the entire infrastructure sector and the adoption of harmonised information model standards,” Kuvaja states.

Relying on the old and developing something new

The majority of the new Nelostie bridges consist of prestressed concrete block bridges, but the project also involved testing some new bridge technologies, such as element bridges, which have become rarer in Finland. In addition to these, the project included twin bridges, reinforced concrete slab bridges and two wooden Versowood cycling and pedestrian bridges.

“These are examples of climate-sustainable bridge-building,” Litmanen says. According to him, Sweco started the groundwork for the bridge designs in collaboration with the Finnish Transport Infrastructure Agency and the main contractor back in the project planning phase in 2018. “We chose the bridge types used in the project, allowing us to prioritise repeatability in the structural design and thus generate cost savings.”

In a design and build contract like this, close partnership between the client, the contractor and the design office is key. “Sweco’s expertise was a great help in the bridge design, and the design work proceeded as planned and on schedule,” Taipale says. Every bridge was also completed on time.

In Mauri Kuvaja’s opinion, one of the key success factors of the project was Destia’s precise scheduling. “The contractor’s ability to organise design and site schedules and work orders ensured smooth transport connections both on the old Nelostie and on the parallel road constructed for site traffic. Kirri is passed by 20,000 vehicles every day.”