JeffJohnson

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Complexity Science & Transport Systems

Jeffrey Johnson & Joan Serras

Design, Development, Environment & MaterialsThe Open University

to infinity and beyond


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The Complex Systems Perspective:

Road systems - interconnected systems of dynamic systems.

Many subsystems: Populations, roads, railways, land uses, regulations.All have multilevel structure, e.g. people, families,

neighbourhoods, cities.All have dynamics => emergent dynamics of whole

Subsystems have thousands or millions of partscan only be modelled on computers.

How to represent and modelling huge heterogeneous multilevelroad systems such as the whole of the UK or Europe ?


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You are here You came in here

or hereor here


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You are here


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9/72 and youre still in England Wales !

Theres a lot of stuff


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11/72 how can we represent so much stuff ?



12/72from micro to macro ?



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Traffic Modelling Conference 31-March-2009 Open University

Everything is becoming more & more connected

MiltonKeynes

Bedford


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MiltonKeynes

Bedford


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MiltonKeynes

Bedford


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MiltonKeynes

Bedford

Cannot divide & rule

- the are connected !


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Objectives of the research

To model road system in an holistic way such that:

captures the dynamics of road traffic:

microdynamics: e.g. shock wavesmacrodynamics: e.g. transmission of congestion


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includes all the smallest level links nothing left out!

aggregates bottom-up dynamics no information loss!


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distributes computation and data naturally acrossadministrative levels


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distributes computation and data naturally acrossadministrative levels

illustrate by huge road systems, e.g. London, Europe


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Starting point: it is like this


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Plots of land zones


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Plots of land zones

ActivityLand Uses


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Plots of land zones

ActivityLand Uses


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origin

destination

Trips are madebetween locatedactivities


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origin

destination


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origin

destination


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origin

destination


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origin

destination


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origin

destination

A route traversesa set of zones atdifferent levels


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Plots aggregateinto larger areas

zones


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Zones aggregate into larger zones


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Larger zones aggregate into even larger zones


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Even larger zones aggregate into even larger zones


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Even larger zones aggregate into even larger zones


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and so on to zones for London, England, Europe,


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We assume there is a hierarchical set of zones

ZN-3 Z N-1 ZN ZN+2 ZN+k-1 ZN+k


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link between junction nodes

kitchen

houseplot,road

segment



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link between junction nodes

kitchen

houseplot,road

segment


Abstract higher level lines(to be explained)


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Define a set of nodes -

where a vehicle can cross aroad zone boundary


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A link is defined by a pair of nodes


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A link is defined by a pair of nodes

conventional links exist at Level N


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A

B

A Level-N route is a set of Level N links


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A

B

There are many N-Level routes between A and B


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A

B



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A

B



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A

B

Let this set of routes be a Level N+2 Link


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There are ~8000 Level-N routes between A and B

AB

~ 20 routes ~ 20 routes ~ 20 routes


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Put a N+2-level nodes on the boundaries

AB


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Make Level N+2 links and a Level N+2 route

AB


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AB


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AB


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We now have 20 + 20 + 20 + 1 = 61


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We now have ~ 100,000 possible routes !

AB

~ 50 routes ~ 50 routes ~ 50 routes


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We now have ~150 + 9 = ~159


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If the routes cross a Level N+3 Zone ..

AB


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AB

make a Level N+3 link as the set of N+2 routes


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AB

Hierarchical routes used for routing trips

Level N+2 linksLevel N+1 linksLevel N+1

Level N linksLevel N links

Within hierarchical zones, always use the highestlevel links available


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AB

Higher level links have lower variance !



relative

frequenc

y

travel time, minutes travel time travel time, hours

100%

relative

frequenc

y

relative

frequency


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AB

Hierarchical routes used for routing trips



Note: higher level links have more stable flowand travel time statistics than lower level links initialisation heuristics ?


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TRANSIMS from Micro simulation to Macro dynamics


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Level N+7

Level N+6

Level N+5

Level N+4

Level N+3

Level N+2

Level N+1

Level N

Level N-1

Level N-2

Level N-3

The World !

Region (e.g. the Americas, Asia )

Nation (e.g. USA, UK )

State (e.g. Virginia, Buckinghamshire)

City, rural region (e.g. New River Valley)

Small town (e.g. Blacksburg, Milton Keynes)

Neighbourhood (e.g. VT Campus)

Conventional Links and zones

Road segment, plot of land

House, garden, garage

Rooms


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Research in Progress

1. Devise new microlevel simulation

2. Implement at microlevel for Milton Keynes

3. Implement hierarchical routing schemes

4. New synthetic micropopulation all properties

5. Run the system for Milton Keynes

6. extend to UK7. extend to Europe

8. extend to infinity, and beyond !

JeffJohnson

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