TRANSPORT MODELLING Lecture 4 TRANSPORT MODELLING Lecture 4 26-Sep-08 [email protected] Transport...

TRANSPORT MODELLINGLecture 4


26-Sep-08

[email protected]

Transport Modelling

Microsimulation Software



26-Sep-08

[email protected]

Traffic Models

Traffic Flow Models

Level of Details Operationalisation

Micro Meso Macro Analytical Simulation



26-Sep-08

[email protected]

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



26-Sep-08

[email protected]

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



26-Sep-08

[email protected]

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



26-Sep-08

[email protected]

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



26-Sep-08

[email protected]

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



26-Sep-08

[email protected]

Popular microsimulation models

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

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

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

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

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

Classification based on traffic conditions

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

Scale of applications

Exis

ting

Mic

ro s

imu

latio

n M

od

els

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



26-Sep-08

[email protected]

Objects modelled

Exis

ting

Mic

ro s

imu

latio

n M

od

els



26-Sep-08

[email protected]

Modelling Techniques

Exis

ting

Mic

ro s

imu

latio

n M

od

els

•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.



26-Sep-08

[email protected]

Modelling Techniques Exis

ting

Mic

ro s

imu

latio

n M

od

els

•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.

TRANSPORT MODELLING Lecture 4 TRANSPORT MODELLING Lecture 4 26-Sep-08 [email protected] Transport...

Documents

Transcript of TRANSPORT MODELLING Lecture 4 TRANSPORT MODELLING Lecture 4 26-Sep-08 [email protected] Transport...