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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
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
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
17
• Full Meso model of very congested area
• 1047 miles
• 2300 signals
• AM, PM, Midday and Overnight models
18
Brooklyn - Queens Model