transport modelling lecture 4 transport modelling lecture 4 26-sep-08 bghosh@tcd.ie transport...
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Transport Modelling
Microsimulation Software
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Traffic Models
Traffic Flow Models
Level of Details Operationalisation
Micro Meso Macro Analytical Simulation
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
The analytical models are, where the solution to a set of differential equations describing the traffic system is obtained analytically (using calculus)
– Analytical models can be static and dynamic
– Numerical methods are used for solutions
The simulation models are, where the successive changes of the traffic system over time (space-time dynamics) are reproduced (approximated) in the model.
– Simulation models are dynamic– Macroscopic, mesoscopic and microscopic
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Traffic Simulation
Simulation: dynamic representation of real world by a computer model
Traffic Simulation: application of computer models/simulations for scientific research in planning, training and demonstration purposes
MAIN FACTORS INFLUENCING RESEARCH IN SIMULATION
1.Advance research in traffic theory 2.Advancement in computer hardware technology 3.Advancement in computer software technology 4.Development in information infrastructure5.Increased importance of traffic and transportation in the society
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Aspects of road traffic simulation (1)
1. Transport networks cover wide physical areas
2. Large number of active participants or users and interaction among them
3. Objectives of the participants can be individual or social (system optimum vs. user optimum)
4. Presence of independent variables outside the control of the operator and the participants (the weather conditions, the number of users, etc.)
5. The variables can be stochastic (inherent randomness) and time varying in nature
6. Man-machine system, laws of interaction dependent on human perception
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Limitations of traffic simulations
Simulations are resource limited
– Resolution: Level of detail– Fidelity: Degree of realism– System size: The network size to be covered– Simulation speed: Speed of simulation compared to real
time– Resources: Computational resources, programming time
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Analysis of Existing Models
Dynamic behaviour of individual agents is explicitly simulated over both time and Space to generate aggregate system behaviour
‘Micro’ refers to the resolution at individual Vehicle level – inevitable requirement of detailed analysis
58 identified models of micro-simulation Models are mostly developed in North America, Europe, Australia and Japan
Types of organisation involved: Research institutes, universities and industrial organisation
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Popular microsimulation models
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Exis
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Micro-simulation models are essentially research products
9 of the popular models are commercial products (AIMSUN2, FLEXSYT II, FRESIM, HUTSIM, INTEGRATION, PARAMICS, THOREAU, TRAF-NETSIM and VISSIM) and are continuously in development
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Objectives
From model designer point,•Quantify the benefits of Intelligent Transportation Systems (ITS), primarily Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS)•Evaluation prior and in parallel with on street operation•study of dynamic traffic control•incident management schemes•real-time route guidance strategies•adaptive intersection signal controls•ramp and mainline metering•toll plazas and lane control systems (lane use signs, electronic toll collection, high occupancy vehicle lane, etc.) •assessing the impact and sensitivity of alternative design parameters
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Classification based on traffic conditions
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Scale of applications
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The scale of application varies then from small type, about 20 km, 50 nodes and 1000 vehicles, to large type, 200 nodes and many thousands vehicles
PARAMICS can even simulate 1 million vehicles with 3000 nodes
Highly specific objectives (models of the type "other" traffic condition) have a very small scale of application
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Objects modelled
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TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Modelling Techniques
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•Weather conditions are modelled by the speed-acceleration behaviour (changes in the driver behaviour parameters) or by the free flow speed of vehicles.
•Parked vehicles are modelled by a particular destination node, side parking on links, temporary incidents or by a particular state of vehicle.
•Commercial vehicles are modelled by parameters such as power, mass, length, privilege on certain lanes.
•Pedestrians are taken into account when turning flows interact with pedestrian areas or in extending intersection all red periods to simulate walk periods.
TRANSPORT MODELLINGLecture 4
TRANSPORT MODELLINGLecture 4
26-Sep-08
bghosh@tcd.ie
Modelling Techniques Exis
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•Incidents are modelled by lane closure signs, blocked lanes, "scheduled vehicles" and slow vehicles.
•Public transport, essentially buses, are modelled by vehicles with fixed routes.
•Traffic calming measures are modelled by local speed limits, yield sign objects, Variable Message Signs and route guidance.
•Queue spill back is modelled by space constraint in car-following and in link changing.
•Weaving is modelled by forced lane changing, special lane changing behaviour, decision rules or lane changing logic.
•Roundabouts are modelled by lane segments and yield sign objects.
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