Newlands Cross Upgrade EIS - European Investment Bank

South Dublin County Council N7 Newlands Cross Upgrade
Environmental Impact Statement
Arup Consulting Engineers
Permanent ground anchors will be installed as excavation proceeds and construction of the
permanent base slab will commence.
The precast prestressed concrete beams for the bridge deck and the permanent GRC formwork
panels will be placed and the reinforced concrete in-situ deck slab will be cast. The surfacing,
parapets, drainage and other finishes for the underpass bridge deck will also be put in place.
Stage 3: The Fonthill / Belgard Road (R113) through traffic will be diverted onto the
completed eastern half of the bridge deck. Construction of the secant piled wall, which will
form the sub-structure for the western half of the bridge deck, will commence.
The precast beams of the bridge deck and the permanent formwork panels will be placed and
the RC deck slab will be cast.
Excavation for the underpass at the remote eastern and western ends of the project will
continue. This excavation will be in open cut with RC retaining walls. Excavation within the
vicinity of the secant piled walls will also continue and again will stop within a safe distance
of the bridge structure. Permanent ground anchors will be installed as excavation proceeds and
construction of the permanent base slab will commence.
The surfacing, parapets, drainage and other finishes for the remainder of the underpass bridge
deck will also be put in place.
Stage 4: Excavation of the underpass beneath and immediately either side of the bridge deck
will commence with ground anchors installed where appropriate as the excavation proceeds.
The base slab to the underpass as well as the road pavement, drainage, safety barriers, and
lighting will be constructed. Fascia panels and other finishes to the carriageway will be
installed.
Stage 5: Eastbound and westbound traffic will be diverted back onto the re-aligned Naas
Road (N7) to provide free flowing traffic beneath the junction. Contra flow operations on the
bridge deck will also be removed when the bridge deck is complete.
Stage 6: The westbound diversion to the south of the underpass will be removed and the final
highway arrangement for the westbound merge and diverge lanes will be completed. The
highway arrangements to the north of the underpass structure will be completed in phases to
facilitate traffic movements.
Stage 7: All remaining highway upgrade works will be completed in stages to the Fonthill
Road, Belgard Road and to the at-grade junction on the bridge deck. All landscaping, lighting
and drainage elements will also be finalised at this time.
3.7.3 Construction Duration
It is estimated that the construction of the Overpass could take up to 2 years.
However, the Underpass Option could take up to 3 years to construct as it would involve
removing a significant quantity of rock to allow the mainline N7 to be placed under the
Fonthill/Belgard Road (R113).
3.7.4 Construction Traffic
It is estimated that at its busiest there will be approximately 20 HGV vehicles per hour
arriving at the site (worst case scenario) for the overpass scheme. The underpass will generate
a greater number of additional movements resulting from the excavation of the rock and the
piling activities.
The speed limit on the temporary road layout during construction will be 60 km/hr during
construction. It is likely that there will be 2 No. entry and 2 No. exit points for construction
traffic in both directions. For the eastbound approach into Dublin it is estimated that there will
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