Brief Description

Fehily Timoney Gifford was the Designer of this project for the NRA and Donegal County Council.

The project consisted of an 11km bypass with both wide single and dual carriageway sections, together with a further 5km of link and side road improvements. A grade separated junction and eight roundabout junctions formed part of the highway improvements while the works required the design and construction of 15 new principal structures including the Cathaleen’s Falls Bridge across the River Erne.

Notable Features

• A ‘landmark’ structure, Cathaleen’s Falls Bridge carries the N15 over the River Erne with a pedestrian bridge below the main deck. The in situ, reinforced concrete arch bridge has a span of 120m.
• Environmental issues required the provision of noise barriers and porous asphalt surfacing.
• The economic drainage design meets the latest environmental standards including analysis of culverts to meet 1 in 100 year storm events. Groundwater flows to the most northerly Turloughs (temporary lakes) in Europe were uninterrupted
• The geotechnical design of an embankment crossing up to 4m of peat overlying 16m of very soft silts was achieved with the installation of 16,000 band drains to allow for construction in 7 stages with surcharging and hold periods totalling 36 weeks.

Fehily Timoney Gifford Responsibilities

• Preparation of conceptual design for tender stage
• Overall project detail design for highways, structures, geotechnical and environmental aspects
• Obtaining technical approvals and consents for various aspects of the proposed design with relevant authorities
• On-site supervision and design office support during the construction period