Tikkurila street, bridge over Vantaa river and undercrossing
Siltanylund Oy, Destia Oy
Design-build project at the Tikkurilantie street in Vantaa linked districts of Tikkurila and Aviapolis to the center of Marja-Vantaa. The project included operations related to design and construction of a new road, bridge crossing over the river Vantaa, pile slabs, underpass and an associated trough. The project was started in 2011 and completed in 2013. The project was one of the first infrastructure projects in Finland in which using building information models was a requirement both for design and construction. In the tender phase it was required to describe how building information models would be utilized.
The bridge crossing the river Vantaa is a pre-tensioned concrete beam bridge that has span lengths of 32 m + 45 m + 32 m and the effective width of about 13 m divided into two lanes and a pedestrian pathway. The bridge was founded on steel piles. The approach embankments of the bridge were founded on pile slabs. The underpass of Tikkurilantie and trough are formed of reinforced concrete circular frame structure that has effective span of 5.9 m and total length of approximately 100 m. Underpass and trough were founded ground-supported. In the area there is predominant pressured water that caused its own challenges for the construction work.
All structures were designed by modeling. The road structures were modeled using Tekla Civil software and bridge and pile slabs using Tekla Structures. Tekla Structures Viewer was used at the construction site and also the inspection consultant was using Tekla Structures. The customer was following the project with Tekla BIMsight. Bridge and underpass structures were modeled to a highly detailed level. Bridge models included all the reinforcements and for the underpass also shoring was modeled. Road structures that were modeled with Tekla Civil were used for automated steering. Furthermore, the usage of bridge models on tablets was piloted in the project.
The models were used as much as possible at the construction site. In addition to automated steering of the road construction machinery, layout information of the bridge was taken almost directly from the model into the layout instruments. Model was used also for installing reinforcement and shoring and the personnel was educated to use Tekla’s programs in the beginning of the project. In addition, during the project a new workflow was tested where contractor would build using only the model information and the customer would approve the model as the final design document instead of the traditional drawings. The customer was able to comment the design with the help of inspection consultant based on the model information. Tekla’s Comment tool application was used for checking the model. In the bridge models different parts had different colors depending on the degree of readiness so it was visually easy to follow up the readiness of parts produced by different project parties. In the design meetings the progress of the bridge design was presented using building information models. The models were updated regularly using online project bank that was available to all project parties.
As the first infrastructure project of this magnitude the project was quite challenging in the beginning. Different stakeholders of the project had to understand what was supposed to be modeled. One of the major challenges was the pressurized water at the trough and therefore the structure had to be watertight. From the structural point of view the curved shape of the trough brought challenges especially for the reinforcement. In addition, different pipes, roadway inlets and pumping stations at the bridge structures caused some reconciling and fixing models both at road planning and bridge design. Also reconciling the pile slabs together with bridge abutments was challenges at times because pile slabs had to include holes at the correct positions for the piles in the bridge foundation. Combining the models was executed mainly using the project bank.
During the project experience was gained especially from technologies that can be used on the construction sites in coming projects. New solutions to model curved structures were discovered. Tekla BIMsight was used for the first time to create a combination model where all the structures could be easily combined. Both the engineering office and customer organization gained valuable experience from model-based checking and approval processes. The use of tablets was evaluated using Tekla BIMsight model on the construction site. Possibly the most efficient way to utilize the bridge models was also found: the design engineer takes a snapshot from the model, adds the necessary comments and sends it directly to the construction site via email.
It was discovered that it is possibly most important to agree on questions related to modeling early enough before the project starts. Questions include what parts should be modeled, modeling tools used, location where the models should be stored and how the models should be utilized. Once the project is up and running, there is no time to go through these things. In that case there would be a risk that the models will not be utilized as much as was originally expected.