METACOR
METACOR is based on a macroscopic, dynamic modeling philosophy. Traffic flow is considered as a fluid with specific characteristics. Motorway traffic flow is described based on 2nd-order flow model; urban traffic flow is described based on 1st-order flow model with particular attention being paid to the intersection modeling. The aggregate variables are density r (vh/km/lane) , mean speed v (km/h) and traffic volume (or flow) q(vh/h). METACOR includes traffic assignment capabilities whereby sub-flows of vehicles with common destinations are explicitly taken into account, and routed along network links. At intersections, the sub-flows are routed according to the splitting rates provided.
The network is represented by a directed graph. More precisely, urban signal intersections, motorway intersections, and on/off ramps are represented by the nodes of the graph, while the motorway and urban stretches between these locations are represented by links. The two directions of a motorway or of an urban stretch are modeled as separate links with opposite directions. Inside each link, geometric characteristics such as number of lanes, upgrade, curvature, etc. are assumed to be homogeneous. A non-homogeneous stretch may be represented by two or more consecutive links separated by nodes at the locations where the change of geometry occurs. At the boundaries of the network, origin and destination links are added where traffic respectively enters and leaves the simulated part of the network.
Software
A friendly graphic display has been developed by Phoenix isi on WIN95-WINNT OS using C++ object oriented-language and the Microsoft Foundation Class (MFC). This enables the users to:
• draw the network easily;
• configure the network easily (input link parameters, traffic parameters, etc.);
• draw the network on a scanned real network to locate the equipment: traffic light, loop detectors, VMS, fixed decors, texts, background network map, etc.
Network configuration functions
• Easy network configuration: origins, destination, links, intersections are identified automatically,
• Associated parameters are activated automatically in the corresponding dialog box.
• Geometric parameters: link length, number of lanes, length, etc.
• Traffic parameters: link capacity, turning rates at each node, associated fundamental diagram, input flow at origins, etc. can be modified by the user.
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Dynamic Graphic Display
During the simulation session:
• Easy configuration of the traffic states for the graphic display: green=fluid; amber=dense; red=congested, etc.
• The number and associated color of the traffic states are chosen by the user.
Output criteria
The overall results of simulation tests using METACOR may be summarized in terms of the following performance indices:
• Travel Time in seconds (TT)
• Total Waiting Time (TWT) at the origins
• Total Time Spent (TTS = TTT+TWT)
• Total Traveled Distance (TTD)
• Total Fuel Consumption (TFC) and pollution
These quantitative assessment criteria are calculated for the overall network and for each axis defined separately.
METACOR applications
METACOR has been used in several European projects: EUROCOR (FR, NL sites), DACCORD (FR, NL sites), QUOVADIS (UK, DK sites), for the development and off-line evaluation of several control strategies: ramp metering, motorway to motorway control, user guidance using VMS, speed control and integrated control applied to corridor network (mixed network: urban +motorway).
References
[1] Haj Salem H., Elloumi N., METACOR: "A Macroscopic Simulation Model of Corridor Traffic, and its Calibration and Validation at the Corridor Périphérique in Paris ", World Congress, Paris 94, ATT Conference
[2] Haj Salem H., M. Papageorgiou M., " METACOR: A Dynamic Macroscopic Simulation Tool for Corridor Traffic", CESA'98-IEEE, Nabeul-Tunisia, April 1998.
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