Dynamic network assignment
models overcome the limitations of static assignment models by capturing the
dynamics of congestion formation and dissipation associated with traffic peak
periods. This enables the evaluation of a wide array of congestion relief
measures, which could include both supply-side and demand-orientated measures.
Classical tactical
network models packages exclude trip generation, distribution and modal split
elements and are therefore suitable for evaluating schemes or policies which
will only cause local re-routing of traffic. Nevertheless recent extensions to
the classical route choice models framework focus on the explicit modelling of
departure time choice that allows the continuous splitting of a static Origin
Destination (O-D) matrix over the time of the day on the basis of the traffic
condition (Metropolis computer simulation software).
On the basis of the
description above the tactical models may be synthetically aggregated in the
following main functional categories:
·
Data processing;
·
General traffic;
·
Safety & accident
records;
·
Signal timing &
warrants;
·
Simulation &
analysis;
·
Traffic control;
·
Traffic maintenance;
·
Transit operations;
·
Transit planning.
Typical application
phases for these models are the demand assignment and the operation of
multimodal transport systems within urban or regional transportation planning,
feasibility studies of new infrastructure, network upgrading and specific
operational measures application in private and public transport systems.
The advantages of tactical network
models are also that they produce output statistics which provide useful
details on the speed-cycle for emissions and fuel consumption analysis,
although aggregated on traffic flows and not available for each vehicle. The
application of tactical networks models to air quality analysis is suitable and
advisable.
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