Faenol Avenue

Faenol Avenue is a single span bridge carrying an unclassified road (Faenol Avenue) over the river Afon Gele located in the town of Abergele, Conwy, Wales. The superstructure consists of rolled steel joists and transversely spanning in-situ unreinforced concrete. The substructures consist of reinforced concrete abutments (integral to adjacent retaining walls) and spread footings. The parapets consist of metallic handrails with two horizontal flat rails and circular vertical infill. The original structure was built at an unknown date.

Scope of services

Nuttall Bowser undertook design surveys to inform feasibility, outline design and detailed design with the aim of increasing the structure capacity from the current 7.5T weight restriction to 40T capability. Nuttall Bowser undertook geometric and condition surveys of the existing assets, topographical survey and ecology surveys. The feasibility report compared options including deck replacement only with retention of existing abutment and footings to whole replacement options including both in-situ and precast concrete portals and box solutions.

Challenges

There were no archive record drawings depicting the shape and founding level of the abutments and foundations.  There is a foul water main running beneath the structure with exact alignment and depth unknown.  

The lack of archive information meant that an assessment of the existing abutment and footings was not viable beyond a qualitative assessment at the current level of loading only – circa 7.5T. An quantitative assessment would have required substantial investigation with associated disruption and costs which may not have led to an assessed capacity at the required 40T rating.

The design solution needed to at least meet or improve upon the current capacity against scour whilst limiting any intrusive works within the watercourse to avoid adverse environmental impact and potential NRW scheme approval rejection.

Value added

Nuttall Bowser provided in depth feasibility reporting including: performance, residual asset life, technical risk, constructibility, safety, initial cost, whole life costs, environmental impact, carbon impact and disruption. We provided estimated carbon use, within whole life performance, to inform carbon impact option scoring for each solution considered.

The proposed solution, comprising an in-situ reinforced concrete portal, improved upon existing weight limitation, maintained similar levels of scour protection whilst limiting intrusive works within the watercourse and provided the geometrical flexibility required to deal with geometric unknowns including interfaces with neighbouring properties.