The Lillholmen bridge, which was completed in 1982, was built on an earth embankment, and between Skräbböle and Gunnarsnäs, Road 12029 passes through the island of Lillholmen across Kyrkfjärden (Kirkkoselkä). In the summer, a busy boatway had passed under the bridge, and the depth below the raising leaf at its northern end had been only 1.7 metres. After the bridge was completed, the barrier effect for water traffic was completely removed from vessels under six metres in height. In addition, the useful width of the bridge increased to nine metres, and the total length is 254 metres. The width of the boat opening was set at 10 metres.
Kreate built a new bridge that replaced the existing reinforced concrete pontoon and the self-service flap at its north end. The embankment was dismantled along the entire length of the new bridge, and the waterflow conditions were improved with a flow opening.
We built the bridge from three separate bridge structures, of which the middle bridge with a 25-metre span is movable and the 4-span fixed bridge sections are on each side of it. The fixed bridge sections are pre-stressed, continuous girder bridges in concrete. The middle section is a non-counterbalanced, hydraulic movable bridge. All the supports of the bridge were based on bored piles, and some of the intermediate supports were anchored through the pile all the way to the bedrock.
Movable bridges are rarely built in Finland, and so the construction of the middle section with its hydraulics and electrical automation as well as careful testing constituted one of the most interesting work phases.
We improved the material management of the project by utilising the material flows generated during the demolition work in the construction. We used the old pontoon bridge in the construction work, and utilised the suitable materials from the road bed for the mass replacement of the new bridge and for the road embankments.
The value of the contract was approximately 8 million euros, and the customer was the Centre for Economic Development, Transport and the Environment for Finland Proper.
