Newlands Cross Upgrade EIS - European Investment Bank

South Dublin County Council N7 Newlands Cross Upgrade
Environmental Impact Statement
Arup Consulting Engineers
Fonthill Road (R113) to just beyond the junction for Newlands Golf Club on the Belgard /
Fonthill Road (R113). An overall scheme layout has been provided in Figure 4.1.
Interchange ramps on all four sides of the junction will allow full access options between the
N7 and the R113. The form of the junction is known as a Diamond Interchange and is
compact by virtue of use of a vertical reinforced earth retaining structure for the N7 with
interchange ramps pulled tight against this structure. The compact form was adopted to limit
the amount of third party land acquisition. In general all third party land take is on the south
side of the junction, principally from Newlands Golf Club and a private land owner on the
east side of Belgard / Fonthill Road (R113) .
A key objective for this scheme is to improve the level of service and safety on the N7
through Newlands Cross. Particular regard was paid to the likely nature of road traffic
coming form from a semi-rural environment to the west of the junction, and the position of
Newlands Cross in a transition zone to a slower speed urban environment. A necessity in this
regard is the removal of all direct accesses in their current form, between the N7 Service Road
east of Newlands Cross and the N7 mainline.
Access to and from Boot Road has been retained, with no direct access from Boot Road to the
N7 for driver safety reasons.
The existing N7 carries a Quality Bus Corridor (QBC) through Newlands Cross. This is
achieved by dedicated bus lanes on both approaches and through the junction. There is no bus
lane on the westbound N7 west of the junction. The existing QBC utilises the N7 Service
Road east of the junction with restricted access to the Service Road for general traffic. There
is also a bus lane on Belgard / Fonthill Road (R113) , terminating just after the junction. There
is no bus lane on Fonthill Road South. The proposed scheme will retain a bus lane on the
eastbound N7 up to Boot Road. Thereafter buses will share the lane for the Service Road /
Fonthill Road. On the westbound N7 a continuous bus lane will be provided along the
diverge up to the junction. The Belgard Road bus lane will be retained as per its current form
in the new scheme.
Throughout the scheme all existing pedestrian and cycle routes have been retained. In general
pedestrian facilities will be improved with the proposed scheme to reflect the likely future
development of this area and the introduction of the Metro line. There is a desire with this
scheme to ensure there is adequate space for pedestrians adjacent to the N7, from a comfort
and perceived safety perspective. To this extent there will always be some degree of
separation between pedestrian routes and N7 mainline traffic.
The scheme has been vertically designed such that the mainline rises from an at-grade position
after the diverge and merges on both sides of the junction. This ensures that all ramps can
remain at-grade, resulting in optimum vertical geometry, limited extent of road embankment
works and ease of construction. An added advantage of at-grade ramps is longer ramps. This
is ideal for the safe operation of diverges as the longer ramp length allows drivers to gradually
adjust their speed to new conditions. There is also more space for queuing in the event of
congestion and there is a lesser likelihood of queuing back onto the N7.
4.2.1 Mainline Horizontal Alignment
In order to minimise permanent landtake, and in particular to minimise impact on existing
buildings in the vicinity of the junction, one of the principle constraints for determining the
position of the mainline centreline was the existing road boundary to the north of the junction.
Other constraints were the tie-in locations at both ends of the scheme. In order to limit land
take to the south, the scheme was brought as tight as possible up to the existing road boundary
to the north.
December 2007 Page 68