The economic appraisal of schemes modelled by microsimulationSIAS is a market leader in the field of traffic and economic assessment, and is retained by central and local government organisations to undertake economic appraisals for road improvement schemes. Traditionally these would require analysis using NESA in Scotland or COBA in England. In some cases, economically marginal schemes have been re-assessed using S-Paramics microsimulation in conjunction with PEARS (Programme for the Economic Assessment of Road Schemes), software specially developed for the economic analysis of microsimulation.
The principal advantages of using S-Paramics and PEARS for combined traffic and economic assessments include the ability to:
As a result, an economic assessment is likely to more accurately reflect the detail of the improvement scheme and capture benefits which are largely invisible to deterministic methodologies. PEARS conforms to the same underlying principles as COBA and NESA, and uses the same economic parameters [Ref: DMRB Vols 13 & 15]. The basic assumptions and algorithms underlying PEARS are consistent with those in COBA and NESA. Re-assessment of various schemes using S-Paramics and PEARS has demonstrated improved benefits, leading to their justification in economic terms.
PEARS, the Program for Economic Assessment of Road Schemes, fulfils the function of a NESA or COBA analysis for a scheme modelled using microsimulation. PEARS calculates the monetary value of changes made to a road scheme and compares them with the costs of implementation. PEARS uses the detailed S-Paramics output and is capable of aggregating results over many runs, so is inherently robust in its treatment of normal variations in traffic flow and congestion. The economic concepts contained within PEARS are compatible with TAG Unit 3.5.6.
Transport Scotland retains PEARS as its cost benefit analysis program for use with microsimulation models. |
Advancing economic analysis through microsimulation :
In common with other traffic flow analysis systems, S-Paramics provides the output necessary to undertake economic assessments using link based or matrix based methodologies. Users may specify S-Paramics hardcopy output to a wide range of formats and levels of detail for subsequent operational or economic analysis. Information on journey times and distances, link traffic flow and average link travel speeds can be specified for output, and most statistics can be summarised by link and O/D pair or even by individual vehicle. Such outputs are subsequently used in the assessment of road network performance to financially quantify travel time, accidents, vehicle operating costs and road maintenance.
S-Paramics outputs detailed information relating to individual vehicle pollution emissions and fuel consumption, which enables environmental performance measures to be established. The output from S-Paramics far exceeds the level of detail necessary to undertake the type of road scheme assessments addressed by the UK Government's standard software COBA and NESA. S-Paramics enables more detailed evaluations of congestion related schemes, such as bus priority measures, the impact of roadworks and the effect of incidents. Because, for instance, incidents are ignored by COBA, potentially the largest benefit to a highway improvement scheme may go unrecorded.
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model
the effects of platooning, and thereby capture the downstream benefits
of the scheme. 
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