Newlands Cross Upgrade EIS - European Investment Bank

South Dublin County Council N7 Newlands Cross Upgrade
Environmental Impact Statement
Arup Consulting Engineers
both eastbound and westbound. It was identified that it was possible to accommodate two
eastbound traffic lanes on the N7 to the north of the works area. The remaining lanes were
seen as being provided on the southern side of the works area and this requirement drove the
need for substantial temporary landtake here. It was envisaged in the assessment that the
vehicle conflicts at the junction of the N7 with Belgard Road (R113) and Fonthill Road South
(R113) would be resolved in a traffic signal junction
5.10.2 Construction Traffic Flows
An estimate has been made of likely construction traffic flows – for heavy vehicles only as
these will have the greatest impact locally. It is estimated that around 400 vehicles two-way
(per day) will be the worst-case construction traffic flow, in 2009. The forecast 2009 flows at
the time of construction is for AADT heavy vehicle flows of approximately 9,000 vehicles per
day two-way on the N7 West; and 1200 HGVs ped day on Fonthill Road. Construction traffic
will add around 200 HGVs per day and 50 HGVs per day at these two locations, which is
equivalent to a 2% and 5% increase respectively in HGV traffic. Thus the impact of
construction vehicles is therefore considered to be not significant.
5.11 Conclusions
• The grade-separated intersection provides an optimum solution which provides
appropriate capacity for Opening and Design Year traffic flow scenarios.
• The at-grade signal controlled junction has appropriate capacity to ensure that significant
queuing does not occur on key links (eg. N7 off-slip roads, R113 link across N7
mainline).
• N7 through-traffic will operate under ‘free-flow’ conditions and will not be affected by
operation of the R113 / N7 junction.
• The impact of construction traffic will not be significant when compared to the levels of
general vehicle traffic at the junction.
• Cost-Benefit appraisal has identified that the scheme has a positive Net Present Value,
which indicates that delay savings will significantly outweigh construction cost.
December 2007 Page 94