Work on the Sofia Northern Tangent was the principal civil engineering project of 2015 for the Bulgarian capital. The purpose was to create a motorway link between the HEMUS motorway (connecting Sofia to the port of Varna in the North-East of Bulgaria) and the STRUMA motorway (serving the South-West).
The company HYDROSTROY AD
won the design and construction contract for the East section involving
more than 8 km of new carriageway and including large-scale backfilling
and numerous crossings. The acces ramps and abutment walls of reinforced
soil specified for seven of these structures represented an area of almost
20,000 m² of facings. Thanks to the responsiveness of the Terre
Armée teams and very proactive sales support by the local team from
Freyssinet Bulgaria, design and supply of this very large retaining
structures project was entrusted to Terre Armée France.
The proposed solution combines TerraPlus® type concrete facing panels and EcoStrapTM reinforcements made of PVA fibers resistant to the alkaline environment. This proposal enabled the company ISA2000, responsible for the earthworks and walls (prefabrication and construction), to use a recycled fill sourced from the steel industry that would have been too aggressive used with standard reinforcements containing polyester fibres.
Another major constraint on this project was the tight deadline. It was imperative for this motorway section to be operational at the end of December 2015 even though the first procurement operations were in late May 2015. In the end, the supply of 50 formwork elements by Terre Armée and full participation by the ISA2000 teams in prefabrication of the panels and the structural work made it possible to meet the deadline while also ensuring high quality completed structures.
This was a major project in Bulgaria and has led to a second contract. Terre Armée has been awarded, by GP GROUP, the contract for the design and supply of Reinforced Earth® walls for construction of the Western Sofia Ring Road, an extension of the Northern Tangent. This time the project involves around 15,000 m² of facing comprising a mix of TerraTrel® green facing panels and TerraPlus® concrete panels.