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Moving through netsAn introduction

Author(s): Axhausen, Kay W.

Publication Date: 2006-02

Permanent Link: https://doi.org/10.3929/ethz-a-005226264

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Introduction

Moving through nets: An introduction

K.W. Axhausen

Arbeitsbericht Verkehrs- und Raumplanung 348 February 2006

Introduction ..._______________________________________________________________________ February 2006

1

Arbeitsbericht Verkehrs- und Raumplanung

Sich in Netzen bewegen: Eine Einleitung

K.W. Axhausen

IVT

ETH

CH – 8093 Zürich

Telefon: +41-1-633 3943

Telefax: +41-1-633 1057

[email protected]

February 2006

Kurzfassung

Dies ist die Einleitung des Buches zur 10th International Conference on Travel Behaviour Research, die im August 2003 vom IVT in Luzern organisiert wurde.. Es skizziert einen theoretischen Rahmen für die in der Konferenz präsentierten Arbeiten.

Schlagworte

10th International Conference on Travel Behaviour Research, Luzern, IATBR

Zitierungsvorschlag

K.W. Axhausen (2005) Moving through nets: An introduction, in K.W. Axhausen (ed.) Moving

Through Nets: The Physical and Social Dimensions of Travel, xx-xx, Elsevier, Oxford.


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Working paper

Moving through nets: An Introduction

K.W. Axhausen

IVT

ETH

CH – 8093 Zürich

Telephone: +41-1-633 3943

Telefax: +41-1-633 1057

[email protected]

February 2006

Abstract

This introductory chapter sketches a conceptual framework for the papers presented at the 10th International Conference on Travel Behaviour research, which was organised by the IVT in Lucerne during August 2003..

Keywords

10th International Conference on Travel Behaviour Research, Lucerne, IATBR

Preferred citation style

K.W. Axhausen (2005) Moving through nets: An introduction, in K.W. Axhausen (ed.) Moving Through Nets: The Physical and Social Dimensions of Travel, xx-xx, Elsevier, Oxford.


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1 A reframing

Travel behaviour research, in particular that informed by the activity-based viewpoint, has

expanded our understanding of travellers and their choices enormously. The International

Association of Travel Behaviour Research (IATBR) has furthered this process through its

now long-standing series of tri-annual conferences (see Table 1 below). Their proceedings

and the literature generally document the increasing refinement of our conceptual frameworks

and models for the behaviours and choices of travellers on individual days. Taste differences,

lifestyles, attitudes and sociodemographics have been added to the description of choice

situations, which are driven by the relative, generalized costs of the activities and their

associated travel. What is mostly missing in the current analysis is a framing, which would

integrate the short- and long-term dynamics of travellers. While the industrialized world will

never again see a similarly dramatic shrinking of its time-space system as it did during the last

fifty years (see Figure 1 for the Swiss example), other major changes should force travel

behaviour analysis to adopt fully dynamic frameworks.

Figure 1 Road travel time-scaled mapping of Switzerland (same scale)

1950 2000

Source: Axhausen and Hurni (2005)

The changes and challenges to the field are both external and internal. The recent difficulties

and costs involved in expanding infrastructure capacity have led to increasing reliance on

demand management approaches to balance the loads on the networks. Transport telematics,

Action spaces, biographies, social networks.. ______________________________________________ February 2006

4

on-line traffic control, road pricing, revenue management of the airlines, but also employer-

based “green travel” come to mind. All of these work because travellers have some flexibility

with regard to their timings, above and beyond other possible changes to their schedule such

as route, mode or destination. These changed timings are likely to affect other days than just

the current one and therefore suggest models which are able to address sequences of days.

The internal logic of the past thirty years of model development points to the microsimulation

of all travel in a study area as the appropriate approach for transferring the results of activity-

based travel analysis into practise. Microsimulations are inherently dynamic and are therefore

able to welcome the external emphasis on behaviour interactions over time. Additionally, the

limitations of the current set of variables to explain behaviour have become clear. While the

models often have good fits, there remains an unease, especially about trip generation, the

stability of behaviour over time, the joint choices of groups and households, the formation of

choice sets and finally the selection and formation of choice rules by travellers. From the

dynamic perspective, and also against an analysis of the missing variables, two issues (and

variable groups) seem obvious: the information assembled by travellers via their biographies,

and the information and abilities inherent in their social networks.

Figure 2 The individual in a dynamic social context

Personalworld

Biography

Projects Learning

Personalworlds of

others

Sharedhistory

and commitments

Household locationsSocial network geography

Mobility tools

Personalworld

Personalworld

Biography

Projects Learning

Personalworlds of

others

Sharedhistory

and commitments

Household locationsSocial network geography

Mobility tools


5

Figure 2 above tries to summarize this view of the traveller in a dynamic social context. The

personal world of the traveller is perhaps better known as his or her mental map, but that

image is limiting, as it emphasizes the geography of the activity space at the expense of other

important elements of knowledge: types of activities known, when and with whom to

undertake them, and the opening hours of facilities. An alternative term for this knowledge

would be activity repertoire, which in turn is weak because it does not refer to the geography

of activity participation. Drawing on the knowledge accumulated over the course of a lifetime,

the traveller selects projects against the background of his or her current commitments.

Longer-term household locations (including workplaces, regularly used shops and other

facilities), social networks and the available mobility tools (such as licences, motorized

vehicles, public transport season tickets and bicycles) are mentioned in Figure 2 The members

of the social network and their personal worlds are both resources and constraints. Their

knowledge, their abilities and their material resources can be drawn on within the limits of

convention and the strength of the personal relationship, which gives the individual extra

leverage in his or her daily life. Their locations, abilities and resources are also limiting, as

they have to be considered in decision making. Consider the trivial case of the joint choice of

a restaurant if one of the members of the group has particularly strong dislikes, such as an

aversion to a cuisine, or is allergic to, say, seafood.

Such a dynamic view of the individual requires a division of the modelled processes into

short-term and long(er)-term ones. One possibility for such a division is suggested in Figure 3

and Figure 4. The understanding sketched here does not require an equilibrium concept, but

assumes a willingness on the part of the individual to improve his or her situation

incrementally. While behaviourally appealing, such an approach might still need equilibrating

mechanisms to produce consistent results in application timeframes.

The central process for the short term (Figure 3) is the formulation of schedules, such as the

complete description of a day (number, type and sequence of activities, their durations and

locations, modes and routes, finally group size and composition for travel and activities). It is

assumed here that the scheduler draws from an activity calendar which lists the activities or,

more generally, activity types that the traveller has to accomplish due to project engagements,

commitments, physiological needs or desires. This list reflects the activity repertoire of the

person, which can be expanded through interaction with others and the environment. As

people generally aim to improve and possibly even optimize their schedules, they will draw

on their mental maps to reduce the effort and uncertainties of the day. We know that

travellers, as a rule, do not fully book their days, but leave slots for the unexpected and the

unplanned. In a simulation framework it might be necessary for the sake of computational


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convenience to impose the assumption that the current day has been fully allocated by some

arbitrary point of time in the previous night.

Figure 3 Modelling the individual’s day-to-day dynamics

The execution of the schedule requires interacting with others in the networks and in activity

opportunity places such as shops, cinemas or other persons’ homes. In some cases the

resulting congestion or the failure of an activity opportunity to deliver the expected service or

good forces travellers to adjust and to reschedule. At the end of the day, travellers will have

updated their knowledge about the elements in their activity repertoires and mental maps.

They may have developed new solutions to the fulfilment of their needs by trying new routes,

modes or locations, by drawing on new information, by expanding their expectation space or

by accepting solutions proposed by others on the basis of their knowledge. The expectation

space is a third view of the personal world. It is the set of heuristics which people develop

about the environment, and their generalizations about the organization of space. Examples

are the heuristics of how and where to find a gasoline station in an otherwise unknown part of

town or expectations about the store composition of a local shopping mall.

Longer-term processes, which structure the shorter-term ones, revolve around the projects

which a traveller formulates to translate his or her life goals and his or her understanding of

him- or herself into reality. In any one period these projects need to be sequenced to provide a

Activity repertoire (t) Activity repertoire (t+1) ................

Activitycalendar (t)

Physiological needsCommitmentsDesiresPending activities

Activityschedule (t)

Mental map (t) Mental map (t+1) ................

Scheduling

Networks, Opportunities

Rescheduling,Execution

Updates,Innovations

Unexecutedactivities

Activity repertoire (t) Activity repertoire (t+1) ................

Activitycalendar (t)

Physiological needsCommitmentsDesiresPending activities

Activityschedule (t)

Mental map (t) Mental map (t+1) ................

Scheduling

Networks, Opportunities

Rescheduling,Execution

Updates,Innovations

Unexecutedactivities


7

reasonable load and prioritization. This planning requires negotiation with others, as many

projects will depend on synchronization with, input of, presence of or permission of others.

Again, the interaction with still others in the markets and networks during execution will

require adjustments and changes, including the abandonment of certain projects or project

elements. The experience will update and expand the individual’s personal world, but also

shape the set of life goals pursued in the next time interval.

Figure 4 Modelling the individual’s longer-term dynamics

The impact on travel behaviour modelling of such a reframing of the task would be profound.

It would move the centre of attention away from the idea of equilibrium and towards concepts

such as innovation, solution generation, life goals and commitments to people and ideas.

These concepts are not unknown to activity-based travel behaviour analysis, but they would

need to be moved centre-stage.

(Life) goals (t) (Life) goals (t+1) ................

Projects (t)[committments]

Definition of „Self“DesiresPending projects

Projectsequence (t)

Personal world (t) Personal world (t+1) ................

Planning, Negotiation

Markets and networks

Replanning,Execution

Updates,Innovations,Reflection

Unexecutedprojects

(Life) goals (t) (Life) goals (t+1) ................

Projects (t)[committments]

Definition of „Self“DesiresPending projects

Projectsequence (t)

Personal world (t) Personal world (t+1) ................

Planning, Negotiation

Markets and networks

Replanning,Execution

Updates,Innovations,Reflection

Unexecutedprojects


8

2 Acknowledgements

This book documents the reviewed keynote papers of the 10th International Conference on

Travel Behaviour Research in Lucerne, August 2003. It gives an excellent, state-of-the-art

overview of the key concerns of the travel behaviour research community. The authors of the

papers were free to achieve this goal by presenting reviews or by challenging through a focus

on new and innovative aspects of the area. The titles of the papers and the names of the

authors speak for themselves, so I will forgo the usual capsule summaries of a book

introduction.

Such an event and the associated book is the product of many hands, which I have the

pleasure and duty to acknowledge.

Dr. Robert Schlich was the main local organizer who made sure that the event during the

hottest week in living memory worked smoothly in an only partially air-conditioned building.

The building, which was ideally suited for our purposes, had generously been made available

by the Schweizerische Hotelfachschule of Lucerne. Dr. Robert Schlich was able to draw on

his colleagues at the Institute for Transport Planning and Systems, ETH Zürich, who set up

the projectors, fixed lap top problems and undertook all the further less exciting but necessary

tasks of such a conference (Sigrun Beige, Saikumar Chalasani, Phillip Fröhlich, Jeremy

Hackney, Arnd König, Stefan Sandmeier, Stefan Schönfelder, Martin Tschopp and Milenko

Vrtic).

The local organizing committee provided important and generous input during the three-year

preparation of the conference: Dr. Michel Bierlaire, EPF Lausanne; Prof. Rico Maggi, USI,

Lugano and Prof. Kai Nagel, then ETH Zürich. The committee was again supported by Dr.

Robert Schlich during this phase. In the same spirit, we were able to draw on the advice and

help of the members of the scientific committee of the conference and of the members of the

IATBR board, who unfortunately are too numerous to list here.

An international conference needs financial support, which was kindly provided by the

Schweizer Nationalfonds, Bundesamt für Strassen, Bundesamt für Raumentwicklung, ETH

Zürich, EPF Lausanne, Universita de la Svizzera Italiana, Migros Kulturprozent, Swiss

Federal Railroads, the Urban Transport Institute and educatis.ch.

The production of this book benefited from the careful and intensive copyediting of Judith

Diane Weston, Karlsruhe, and from the graphic design skills of Andreas Gähwiler, ETH

Zürich.


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3 Literature

Axhausen, K.W. and L. Hurni (eds.) (2005) Zeitkarten Schweiz 1950-2000, IVT and IKA, ETH Zürich, Zürich.

1 History of the series


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Table 1 History of the series

Year Location Title Reference

1 June 1973 South Berwick, Maine

Issues in Behavioral Demand Modeling and the Evaluation of Travel Time

TRB (ed.) (1974) Behavioral Demand Modeling and Valuation of Travel Time, Special Report, 149, Transportation Research Board, Washington, D.C.

2 May 1975 Asheville, North Carolina

Second International Conference on Behavioral Travel Demand

Stopher, P.R. and A.H. Meyburg (eds.) (1976) Behavioral Travel-Demand Models, Lexington Books, Lexington.

3 April 1977 Tanunda, South Australia

Third International Conference on Behavioural Travel Modelling

Hensher, D. A. and P.R. Stopher (eds.) (1979) Behavioural Travel Modelling, Croom Helm, London.

4 July 1979 Grainau, Germany

Fourth International Conference on Behavioural Travel Modelling

Stopher, P.R., A.H. Meyburg and W. Brög (eds.) (1981) New Horizons in Travel-Behavior Research, Lexington Books, Lexington.

5 October 1982

Easton, Maryland

Fifth International Conference on Travel Analysis Methods

TRB (ed.) (1983) Travel analysis methods for the 1980s, Special Report, 201, Transportation Research Board, Washington, D.C.

6 April 1985 Nordwijk, Netherlands

1985 International Conference on Travel Behaviour

Rijkswaterstaat (ed.) (1986) Behavioural Research for Transport Policy, VNU Science Press, Utrecht

7 October 1987

Aix-en-Provence, France

Fifth International Conference on Travel Behaviour

International Association for Travel Behaviour (ed.) (1989) Travel Behaviour Research, Avebury, Aldershot.

8 May 1991 Quebec, Quebec International Conference on Travel Behavior Research

Stopher, P.R. and M.E.H. Lee-Gosselin (eds.) (1997) Understanding Travel Behavior in an Era of Change, Pergamon, Oxford.

9 June 1994 Valle Nevada, Chile

Seventh International Conference on Travel Behaviour

Ortuzar, J. de Dios, D.A. Hensher and S. Jara-Diaz (eds.) (1998) Travel Behaviour Research: An Update, Pergamon, Oxford.

10 September 1997

Austin, Texas Eight International Conference on Travel Behavior Research

Mahmassani, H. (ed.) (2002) In Perpetual Motion: Travel Behaviour Research Opportunities and Application Challenges, Pergamon, Oxford.

11 June 2000 Goldcoast, Queensland

Ninth International Conference on Travel Behaviour Research

Hensher, D.A. (ed.) (2001) The Leading Edge in Travel Behaviour Research, Pergamon, Oxford.

12 August 2003

Lucerne, Switzerland

Tenth International Conference on Travel Behaviour Research

Axhausen, K.W. (ed.) (2005) Moving Through Nets: The Physical and Social Dimensions of Travel, Pergamon, Oxford.

13 August 2006

Kyoto, Japan Eleventh International Conference on Travel Behaviour Research

The Expanding Sphere of Travel Behaviour Research


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