Virginia and Washington DC

Joint SimCap Meeting

January 15, 2019

Mesoscopic and Hybrid Modelingin Aimsun

Murat Ayçin, PhD

Modeling Levels

• All models in same network

• Allows exchange of information• Path files from higher

models can be utilized

2

Traversal OD

Matrices &

adjustment

DTA with DUE, paths

assignment file

Detailed simulation,

Pedestrians

Models

Macro Assignment: ✓ capacity, vdf, turn penalty functions

✓ does not represent individual vehicles

✓ does not consider signals (signals can still be represented by turn penalties)

✓ No animation

Micro✓ Detailed vehicle simulation

✓ Updates vehicles every time step and provides animation

✓ not suitable for very large networks since demanding computationally

✓ Calibration involves representing individual vehicle behavior which limits its suitability for large networks

3

What is Meso?

• Efficient way of modeling vehicle movements

• Detailed vehicle based simulation like microscopic

• Discrete-Event Simulation

• No Animation during simulation (it can be recorded for playing back later)

4

Traversal OD

Matrices &

adjustment

DTA with DUE, paths

assignment file

Detailed simulation,

Pedestrians

Meso Model Approach

• Movement of individual vehicles.

• The model calculates the time at which each vehicle enters and exits a section (instead of the position of each vehicle over time)

• Discrete event simulation: Not all vehicles updated at the same time

• Simplified car-following, lane-changing, gap-acceptance

5 Discrete-event

Meso Parameters

Jam Density : Specifies storage capacity of sections and turns. Select a jam density considering vehicle mix.

SectionCapacity = JamDensity * Length * NumberLanes

TurnCapacity = JamDensity * Length * NumberLanes

Look Ahead: Sets the distance from decision point for lane changing.

7

Lane-Changing

• Look-ahead distance controls the shape of the queue.

• Global parameter by road type but can be modified locally.

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1

4

Lane-Changing

If look-ahead is too short,the queue blocks all lanes

If look-ahead is too long,vehicles queue too farin advance

Queuing for left turn

Hybrid Simulator

Inside the Meso model, pockets of microsimulation can be created for animation and detailed modeling.

Traversal OD

Matrices &

adjustment

DTA with DUE, paths

assignment file

Detailed simulation,

Pedestrians

HYBRID

Hybrid Simulator

MesoModel

Microsimulation area

Hybrid Simulator

Advantages:

• No need to extract a smaller subarea for a

microsimulation.

• Operations can be studied in detail inside micro area:

➢ Interactions of pedestrians and vehicles,

➢ merging and weaving behaviour of on and off ramps,

➢ traffic incidents,

➢ transit signal priority actions

• Path costs between OD’s will consider operations

inside the micro area. More realistic behaviour.

• Animation during simulation

Hybrid Modeling Example

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Meso and Hybrid Project Examples

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PanAM Games Model

• Pan Am Games held in July 2015, Toronto, Canada

• Hybrid model: Microsimulaton of highways with HOV lanes

• Over 1500 signals

• 366 miles of highway and ramps

16

San Diego

• Full San Diego region model in Meso

• 24 hour model with 8.8 mil trips

• 9290 miles of roadways

• 3600 actuated signals

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• Full Meso model of very congested area

• 1047 miles

• 2300 signals

• AM, PM, Midday and Overnight models

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Brooklyn - Queens Model

Thank you

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