Microsimulation Presentation

8/14/2019 Microsimulation Presentation

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An introduction to microsimulation


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Limitations of traffic models


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What does microsimulation deliver ?

Provides the means to fully test the likely traffic flow

responses to proposed network changes at a detailedlevel

Helps transport planners to design road networks, traffic

management schemes and UTC systems

Outputs 3D visual graphics as well as detailednumerical data

Allows variation in traffic flows and conditions to be

accounted for in assessments by undertaking and

analysing multiple model runs

Allows operational and economic assessments of

scheme options and comparison with reference network

to be undertaken


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How does microsimulation work?

o It works in the same way thatroad users think

o Applies simple rules :

speed / car following

lane changing

gap acceptance

driver behaviour

route choice


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Drivers behave d if ferent ly

To reflect this, microsimulation

assigns parameters which influence:

Speed and overtaking

Gaps to move into

When to be in the right lane


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Speed :

What speed do I

wantto do?

What speed canI

do?

What speed mus tI

do?

Do I maintain my

speed, accelerate or

decelerate?


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Lane Changing :

What lanes can I use now?

What lane do I need to be in

soon?

Do I need to change lane?

Can I change lane?


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Considerat ion of other vehic les:

Car following : Am I too

close?

Lane behaviour : Should I

slow to let someone else

manoeuvre?

Gap acceptance : Can I move

out now?


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Signals:

To model wide area urban traffic flow

in congested networks it is essential to

include control systems in the

simulation

In simple networks this might just

require the inclusion of fixed time

signals

In complex networks, because driversreact to changing conditions, signal

optimisation and UTC systems can be

included.


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Vehicle routeing :

Major and minor routes


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Vehicle routeing :

Find the quickest way

Some drivers will avoid

congestion, but others may not

Waypoints for longer journeys

Route choice advice from ITS

Public transport fixed routes


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Vehicle routeing :

Waypoints

strategic and local networks in one model


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Organised chaos :

Cause and effect is an

important feature of

congested road networks.

Only microsimulation can

model this.


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Microsimulation model inputs

Hardly d i f fer f rom other model l ing

system inputs :

Principal difference is thedependence on data in smaller

time intervals

The source of trip demand data is

common to all traffic flow models


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Microsimulation model inputs

Hardly d i f fer f rom other model l ing

system inputs :

The development of trip demandmatrices is crucial for any form of

modelling


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Fuzzy model l ing = Statist ical

est imates of o utputs

ie. no single num ber answ ers


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1. A platoon builds up behind

a lorry (yellow arrow)

heading north on the A77

from Stranraer.

2. The platoon approaches

the WS2+1 section. The

second blue car anticipates

overtaking.


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3. The second blue car is the

first to overtake.

4. The blue car clears the

head of the platoon.


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5. Meanwhile, the maroon

Mercedes (arrowed white in

Fig.1) has also overtaken.

This is the driver's view.

6. The blue car reaches the

end of the overtaking

section.


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7. The blue and maroon cars

speed away from the head

of the platoon, enjoying the

downstream time benefit.

8. The rest of the platoon exits

the overtaking section,

heading north to the

next one.


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Documents

Microsimulation Presentation