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Introduction
EMME2 - INRO (CANADA) package, set on the Venice municipal territory, is made up
of many modules. The two most important of these are:
a) assignation model of vehicular traffic to
road network.
b) assignation model of passengers to collective
transport network.
The
two models research the mode that minimizes time and cost of user transfer on
their respective transport networks, by considering:
- a series of attributes about road
links and junctions;
- feasible transit tolls;
- parking rates;
- a series of attributes about
collective transport services;
- tariffs as distinguished by type of
users.
The Transport and Mobility Office of the Venice City
Administration has developed and applied a supplementary module, the so-called
“modal allocation”. This module measures user shift
between individual and collective means dependent on policies for
strengthening/rating/regulating various systems of transportation. The
Transport and Mobility Office has also used EMME2 to analyse commercial traffic
trends at urban level.
Practical use of
EMME2
The EMME2 model is set for short, medium and long term
planning at urban scale for both the PGTU (Urban Traffic Plan) and for the PUM
(Urban Transport Plan). Other possible applications requiring greater detail
such as for designing road intersections, need more
traffic surveys and the application of micro-simulation models for which the
EMME2 model assures all relevant data classification and input.
At the moment only one micro-simulation model is
available. This is the TOS, applicable to single intersections and used to
optimize the functioning of a semaphore network. Another dynamic
micro-simulation model is under acquisition (PARAMICS): it deals with sets of
intersections, in order to offer the Administration complete assistance for all
decisions that must be taken.
Input and output
data
EMME2 needs the following input data:
- geo-referred description of road
network topology ;
- description of every feature of
each link (length, number of lanes, type of link, outflow rate curve, maximum
speed);
- description of every junction
subjected to an installation of traffic lights or to precedence rules;
- description of routes, stops,
frequency, maximum speed for each line of public collective transport;
- territory representation in terms
of origin and destination zones;
- mobility demand description distinguished
by means of transportation (individual and collective), reasons (work, study,
other reasons) and origin/destination journeys.
EMME2 model outputs are based on one hour periods and are
available for rush hour in the morning and in the afternoon.
For every simulated scenario, EMME2 generates statistics
on:
- general and average duration of journey
distinguished by type of users;
- costs of journeys;
- vehicles per km (for all the
computed means of transportation);
- average distances run as
distinguished by type of users (workers, students, other travellers);
- atmospheric emissions from vehicular traffic.
Moreover many graphic elaborations can be made:
- map of origin/destination journeys
for each zone;
- map of vehicular traffic flows on
the network of roads;
- map of road congestion levels (on
links and junctions);
- map of passenger flows on public
collective transport networks and number of people ascending and descending;
- map of isochronous
movements from one zone to all the other ones;
- map of comparison between different
scenarios.
Correlation with
traffic data
EMME2 model is not interfaced with the main traffic lights
system because of the scarce reliability of the counting devices (located near
the traffic lights); this is
why they aren’t used regularly for modelling. For monitoring
purposes, they are periodically downloaded and used to check the
reliability/relevance of the simulation model that needs to be updated every
three years.
Module for
atmospheric emissions calculation
Atmospheric emissions calculation is made on a hourly basis and evaluates:
- vehicular traffic composition
(heavy-duty and light-duty vehicles);
- flows for each link;
- speed for each link;
- loss of time at junctions.
Another module prepared by the Municipal Transport and
Mobility Office helps to evaluate traffic noise propagation: it considers,
besides the factors mentioned before, structure of buildings and open spaces
and presence of mitigating elements (like barriers and pavements covered with
acoustic sound-deadening material).
EMME2 advantages and
disadvantages
EMME2 main advantages provide:
- a better aptitude to foresee critical
urban development and the impact of new big attractors (office districts,
commercial districts, etc.);
- enhanced support for drafting
technical feasibility studies for new infrastructure;
- improved capacity in identifying
park-and-ride locations;
- greater accuracy in attributing
rules and functions to collective transport systems and to complex junctions of
passenger exchange;
- greater capacity in evaluating
performances of future infrastructure networks;
- greater awareness in planning
priority elements of the infrastructure ;
- more efficient communication to the
public of resulting transport scenarios.
The most important disadvantage is associated to the
difficulty of training and maintaining a group of qualified technicians that
utilize the EMME2 software and update its databases.
Acknowledgments
This text has been kindly made available by
the Municipal Transport and Mobility Office (Comune di Venezia, Ufficio
Mobilità). |