Refurbishment of a 100m long four-span road bridge that spans the River Wye. The project required the demolition and reconstruction of reinforced concrete cross heads, piers and cantilever deck sections within a sensitive ecosystem and high river levels.
During buildability reviews, we redesigned the construction approach for the demolition and removal of more than 200m3 of concrete. The original approach was a hydro-demolition solution, which was deemed too damaging to the sensitive eco-system. We suggested using diamond wire cutting, which resulted in dry cutting and removal of concrete elements in segments, eliminating environmental risks.
Using this technique the existing pier support structure was cut and removed in 1m3 segments while the piers were temporarily supported. The segments needed to be handled within the temporary structure and transported to the bridge deck level for disposal while the bridge was temporarily supported. We worked collaboratively with our temporary works designers and our suppliers to devise an innovative temporary works solution that not only supported the bridge deck and wind loadings but also allowed for the handling of the concrete removal and loading. The temporary works structure provided access for the diamond wire cutting and concrete handling and also provided access for other trades with an integrated cantilever deck support and crosshead support systems.
Following successful completion of the demolition and re-construction works, other works involved installation of 30 new bridge bearings, painting existing structural steel works, installation of new corbel steelwork to support the parapet edge beam, installation of new drainage and surfacing and waterproofing the bridge deck.
Works were completed 11 weeks early, within budget and without any environmental incidents. Our approach won the Innovation Award in both 2015 Constructing Excellence and 2015 Institution of Civil Engineers Wales Awards.
Powys County Council