📋 Tender Overview
The more than a hundred-year-old stone bridge located in the cultural landscape of the center of Pomarku was banned in the fall of 2016. After a long process an atypical solution was created instead a concrete bridge covered with the stones of the old bridge which was opened to traffic in 2020. In this story we will tell you what the exceptional project contained.There was not only movement on the bridge due to traffic loads but you could clearly see the movement of stones with the naked eye. It was difficult to know where the limit for excessive load was so the bridge was completely closed at the end of 2016.This is what Heini Raunio an expert on the load-bearing capacity of bridges at the Norwegian Railways Agency says about the stone bridge over the Pomarkunjoki which in 2016 had reached more than a hundred years of age. The church village of Pomarku is also a nationally significant cultural environment where the bridge located had already been under intensive observation for a long time. The first changes were noticed already in 2000 and in the 2010s more detailed monitoring began.In 2016 ever-tightening weight restrictions were imposed on the bridge. First 20 tons then three then two. In the end the ELY center of Varsinais-Finland decided to completely close the bridge to traffic in November 2016. Even after that one of the threats was that the entire bridge would go into the river with the departure of the ice if it was not dismantled soon.There were and are still protected buildings on both sides of the stone bridge and the bridge belonged to the same entity. The old Kylnraitti of the municipality of Pomarku which runs on the spot was awarded the Safa award of the Finnish Association of Architects in 1982. It is therefore an important historical landmark and a big part of the identity of the people of the municipality as the songs related to the bridge project made by the Kahden tonnin duo from Pomarku which can be found on YouTube speak for themselves.Negotiations on the possible repair or renewal of the bridge had already been going on for quite some time when the bridge was finally closed to traffic. The discussions were not easy the process was long and many different perspectives had to be taken into account. Securing the bridges cultural heritage value traffic safety and the bridges load-bearing capacity combined with scarce road funds became a special challenge.The bridge was literally falling apart but understandably we wanted to cherish it for as long as possible. Thats why all the stones were turned when it came to repairing the bridge but it simply wouldnt have been possible in a sustainable way. The location in the cultural landscape colored the whole project and a lot of emotions were involved Raunio remembers. .This one easily comes out on top in terms of its memorability and uniqueness when I think about my own bridge projects over the years sums up Heikki Lilja a bridge expert with a long career from the Norwegian Railway Agency.Many different actors involvedThe project that led to the renewal of the bridge got more rounds as different actors joined the negotiations. They were started between the ELY center of Varsinais-Finland and the Satakunta Museum after which the Transport Agency now Vylvirasto the Museum Agency and the municipality of Pomarku got involved.From the point of view of the highway operator the most effective solution would have been to build a completely new bridge. However there was no intention at any stage to build a completely basic bridge because it is a great and important area. We had to seek a compromise solution at the latest when the old bridge was banned says the Highways Agencys engineer and Minna Torkkeli head of the environment department .The old bridge was built in 1907 and it was not designed to carry such large loads as for example caused by todays agricultural machinery. The ban on use was the only option to guarantee safety as the strict weight restrictions were not obeyed enough. But why was it not possible to repair the bridgeThe bridge type was problematic overall. A stone arch structure is challenging and in this case the arch had already lost its shape. If the old bridge had been repaired the weight restrictions would never have been removed and the project would perhaps have been even more expensive sums up Raunio.However not everyone wanted to believe at first that repairing the bridge was not possible. This stalled negotiations to build a new bridge.The initial phase of the project was challenging but when the decision on a new bridge was finally made we got to the normal process. Of course the site was exceptional remembers Jari Nikki a bridge expert at the Vylvirasto who worked as a bridge engineer at the ELY center in Varsinais-Finland during the project.A unique trickIn the end it was decided to replace the old bridge with a kind of hybrid model a modern reinforced concrete bridge on the inside which looks like an old bridge on the outside. This was realized by using stones from the old bridge in the cladding. The method of operation is exceptional.When a bridge of the type and shape of an old stone arch bridge was found to be the best option for the site the idea came to use old stones in the new structure. It is very rare that the materials of an old bridge are saved and reused says Lilja.A unique trick meant that the stones were preserved and later sawn to the appropriate thickness for cladding the new bridge.The stones were numbered moved to the storage area sawn into pieces in the stone carving workshop and placed in the mold of the new bridge. So the stones do not carry anything in the new bridge but are mostly decorative. The stones still have their own important function in protecting the concrete surface from natural forces.
