Norwegian Highways Agency - Hydrodemolition of Underwater Bridge Pillars
Underwater Hydrodemolition works wonders in Norway
- Customer: Norwegian Highways Agency
- Service: Concrete hydrodemolition and Surface preparation
- Industry: Civil Engineering
When RGL deployed hydrodemolition techniques during underwater surface preparation on a bridge project in Northern Norway; they generated significant cost savings and improved safety by eliminating the need for divers or other operatives, to be in the work areas whilst material was being removed.
The Arstein Bridge in the north of Norway was built in the 1940s from reinforced concrete. The structure, a single carriageway supported by 11 pairs of columns joined above water by a crosshead beam, had suffered from extensive degradation over a 70+ year history and the concrete and steel of these columns, especially around the splash zone and needed to be recovered.
The depth of damaged concrete ranged between 25 – 150mm and in total more than 1500m² was treated.
Using a bespoke 1500mm diameter pile ring multi-modular frame system the goal was to prepare each column for the installation of stainless-steel reinforcement to be fixed before reinstatement of a new concrete casing.
Working remotely, from a barge, RGL was able to set the jet angle, number of passes and speed of travel of the Hydrodemolition rig to make a controlled traverse in a complete circle of the column, before ‘auto indexing’ to the next level and continuing until the cycle was completed.
Jeremy Twigg, RGL’s Commercial Director acted as site liaison and confirmed that, had RGL employed divers for the underwater preparation work, “It would have taken 10 times longer and the quality achieved by hydrodemolition was so much better.”
“Remote control of our hydrodemolition robots greatly helps towards ensuring continuous reliability in the harsh environment at Arstein; working in deep water and temperatures below 4ºC meant unnecessary time or operatives in a high-risk environment could be eliminated. As no jackhammers are used in the hydrodemolition process, we were able to achieve a much higher the quality of finish on the bridge repairs too”.
RGL’s underwater hydrodemolition solution proved to be ideal at meeting the project requirements and tight schedule, reducing the planned timeframe by several days.
The depth of the fjord was 16m which meant as work progressed, underwater checks were carried out both by divers on hand and through underwater camera surveillance to ensure that an even finish was achieved across each column.
The project ran for a total of three months with all 22 columns being completed. The result ensured all stakeholders were satisfied including the Norwegian Highways Agency, PEAB Civil Engineering and Multibetong.
If you would like to know more about our underwater Hydrodemolition services, Contact RGL today.
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