Newlands Cross Upgrade EIS - European Investment Bank

South Dublin County Council Newlands Cross Grade Separation
Traffic Modelling: Working Paper No. 1
2.1.7 Scenario Testing
2009 and 2024 Do-Something network scenarios were created to assess the proposed options.
The 2009 and 2024 networks and matrices were assessed with SATURN for the above
proposed junction improvements to determine any local and wider effects on traffic on the
network..
3. PRELIMINARY DESIGN AND EIS
The traffic model assessment results were used to produce information for the preliminary
design and environmental assessment of the preferred option.
3.1 Environmental Impact Assessment
Twenty-four-hour link counts on a number of road links identified as representative of the
different daily traffic patterns present in the network were used to calculate appropriate local
conversion factors, which were used to convert AM peak volumes into daily and other
average volumes, as required for the environmental impact assessment in the EIS.
3.2 Cost Benefit Analysis
Arup carried out a Cost Benefit Analysis (CBA) of the proposed improvements. COBA 11
(the NRA’s standard tool) was used.
3.2.1 Traffic Growth
The modelled area is urban in nature, suffers congestion during peak periods and benefits
from a significant PT provision that will be enhanced and improved in the future. NRA
standard high and growth rates as provided in the NRA’s CBA Guidelines are not appropriate
for this urban environment and therefore local growth rates were input into COBA based on
the DTO predictions for the 2009 and 2024 traffic scenarios – which effectively caps growth
rates input into COBA..
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REPORT_FINAL REV1.DOC
Page 6 Arup Consulting Engineers
Final 3 November 2005