Undulating Fluvial/Glacial Terrain along the Route
AlignmentA 17km redevelopment of the N14 highway has
been proposed in County Donegal, Ireland in order to improve safety
and infrastructure in the region. The N14 is currently a single
lane highway running between the towns of Lifford and
Letterkenny.
We undertook a desk and field based terrain analysis to identify,
classify and delineate those potential geomorphological,
geological, geotechnical and hydrogeological constraints to
possible corridors for the new highway. This geotechnical
constraint study was combined with environmental and infrastructure
constraints Mott MacDonald identified in order to select a
preferred route.
Terrain Analysis MapThe preferred
scheme runs from the south of Lifford, adjacent to the River Foyle,
and extends northwest to the N14/N13 junction near Manorcunningham.
A number of bridge structures will be required at both road and
river crossings, along with junctions at existing roads. The new
scheme requires approximately 14km of new carriageway and widening
of approximately 3km of the existing highway. In addition, a new
1.3km link road and bridge crossing is proposed to link the new
highway with the A5 at Strabane.
Main Ground Investigation
Mott MacDonald was commissioned by Donegal County Council to
design, prepare contract documents, manage and supervise a
geotechnical ground investigation for the preferred route.
The ground investigation was targeted within each identified
terrain unit in order to characterise the geotechnical constraints
identified and provide robust ground information for development of
the preliminary design and also to allow prospective design and
build contractors to price their tenders with due regard to the
prevalent ground issues. Ground investigations were undertaken by
Geotech Specialists Ltd between June and August 2005. Mott
MacDonald acted as Engineer to the contract.
Terrain evaluation
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