The Grandfather Bridge is a full-blooded BIM project from the tender to the opening of the bridge and beyond.
The Isoisänsilta project, which aimed to achieve paperless design and construction, created new practices for transferring information from one party to another. Design by modelling reduced errors and made the transfer of information faster and clearer. This resulted in significant time and resource savings for the parties involved.
A slick start to information modelling
BIM was a fairly new thing for the main contractor, Kreate, when they started on the Isoisänsilta project. However, using Tekla software for a full-blooded information modelling project seemed like an easy task. Aki Kopra, project engineer at KRETE, says that the information modelling was used throughout the project, from the tender phase to delivery.
"During the tender phase of the project, the data model was an official and binding document. I believe that this type of approach will become more common, but for me this was the first time. However, a well-done bridge model made our tender calculations much easier," says Aki Kopra.
"BIM helps us to improve the efficiency of construction. " Ville Alajoki, Project Manager, City of Helsinki Building Department
Common understanding
In the Grandfather Bridge project, BIM was not only a way of working at the design stage, but data models were used for scheduling, construction support and supervision, and installation of structures. For example, steel structures were given three different statuses for scheduling - design, fabrication and installation - and concrete casting was scheduled in the data model.
A data model was used to visualise the stages of the project for the client, and the engineering company that supplied the steel structures used the data model for scheduling and smooth cooperation between the site and the fabrication department. Kopra emphasises that the three-dimensional visualisation of the structures using Tekla significantly helped the processing of information, for example on site. The bridge design process was smooth and avoiding mistakes saved time. Tekla Field3D was also used extensively on site and was a great help in visualising the structures.
"Design is simpler and clearer with modelling, and visibility to other project participants is better. The data model helped the site team to better understand the bridge structures. This makes the design and the whole project smoother, faster and more error-free," says Jarkko Savolainen, BIM expert for the project at A-Insinööre. The project partners decided to use Tekla Model Sharing to share the composite model. The model was kept up to date and all parties received the information they needed.
Manufacture, acquisition and disposal
The project used data models to produce the structures. Challenging steel structures were modelled for the machine shop, and the model was used for fabrication. When the temporary steel structures were removed, the bridge took the final shape designed by the architect. The steel superstructure was successfully adapted to the concrete deck supports.
The structural design was successfully carried out by modelling, and the coordination of the installation was particularly smooth. Aki Kopra says that procurement and material deliveries were more efficient with the use of information modelling, as the reinforcement for the bridge structures was delivered directly to the site on time.
"The schedule made it easy to time the deliveries correctly and the site never stood still because of missing parts. Accurate deliveries also make it much easier when there is not much space on site," says Kopra about the benefits of BIM during construction.
The data model will also be useful for the City of Helsinki, which owns the bridge and is commissioning the project. Project Director Ville Alajoki from the City of Helsinki's Department of Public Works considers the project a great success.
"The project was a great success. Quality improves immediately when you get it right the first time and don't have to correct mistakes. I believe that the new technology will enable new innovations, and soon we will be able to produce reinforcement for a bridge as a whole, changing the shape of the construction and improving efficiency even further." Ville Alajoki, Project Manager, Helsinki City Construction Office
Grandfather's bridge
Location: in Helsinki
Tension: 144,3 metres
Width: 4 metres
Shape: the bridge widens at one end, where the traffic flow is split in two directions
Height of descent: 4,7 metres
Deck structures: steel
Bridge deck: depends on 22 pairs of drawbars
Cover mounting blocks welded in place on site
