Psychological Aspects of
Travel Information Presentation
A psychological and ergonomic view on travellers’ response
to travel information
Psychological Aspects of
Travel Information Presentation
A psychological and ergonomic view on travellers’ response
to travel information
Proefschrift
ter verkrijging van de graad van doctor aan de Technische Universiteit Delft,
op gezag van de rector Magnificus prof. ir. K.C.A.M. Luyben, voorzitter van het College voor Promoties,
in het openbaar te verdedigen op woensdag 17 oktober 2012 om 12.30 uur door
Matthijs DICKE
Master of Science in Psychology Geboren te Roden
Prof. dr. K.A. Brookhuis.
Samenstelling Promotiecommissie:
Rector Magnificus Voorzitter
Prof. dr. K.A. Brookhuis Technische Universiteit Delft, promotor
Prof. dr. E.M. Steg Rijksuniversiteit Groningen
Prof. dr. ir. S.P. Hoogendoorn Technische Universiteit Delft Prof. dr. G.P. van Wee Technische Universiteit Delft Prof. dr. ir. E.C. van Berkum Universiteit Twente
Prof. dr. W.H. Brouwer Rijksuniversiteit Groningen
Dr. D. de Waard Rijksuniversiteit Groningen
Prof. dr. ir. H. Priemus Technische Universiteit Delft, reservelid
Dit proefschrift is het resultaat van onderzoek in de periode tussen 2002 en 2005 uitgevoerd bij de Rijksuniversiteit Groningen, faculteit Gedrags- en maatschappijwetenschappen en de Technische Universiteit Delft, faculteit Techniek, Bestuur en Management. Het onderzoek maakte deel uit van het AMICI (Advanced Multi-agent Information and Control for Integrated multi-class traffic networks) onderzoeksprogramma, onderdeel van het programma Verkeer en Vervoer gefinancierd door NWO en Connekt.
TRAIL Thesis Series T2012/5, the Netherlands TRAIL Research School TRAIL Research School
P.O. Box 5017 2600 GA Delft The Netherlands T: +31 (0) 15 278 6046 F: +31 (0) 15 278 4333 E: info@rstrail.nl ISBN: 978-90-5584-159-2
Copyright © 2012 by Matthijs Dicke-Ogenia
All rights reserved. No part of the material protect by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the author.
The proof of the pudding is the eating Miguel de Cervantes, 1547-1616.
i
Voorwoord
Dit hoofdstuk is ongeveer het laatste wat ik opschrijf voor mijn proefschrift. Misschien wel het stukje met de meeste tijdsdruk (hoewel de lengte anders doet vermoeden). En tegelijkertijd ook een erg belangrijk stuk. Ik vermoed dat de samenvatting en het dankwoord vele malen vaker gelezen worden dan de overige hoofdstukken.
U bent als lezer toch wel benieuwd: sta ik in het dankwoord (en als ik erin sta, welke woorden benadrukt hij), of wie is die Matthijs eigenlijk, wat voor hobbies heeft hij, wie zijn zijn vrienden, is uit de tekst op te maken of er strubbelingen waren met begeleiders of anderen? Hoe is zijn band met zijn familie? En wie zijn Jacqueline, Noor, Daniël en Evi? En waarom heeft hij er eigenlijk zo lang over gedaan!?
Ik ga op die laatste vraag kort in. Want even overwoog ik in plaats van een dankwoord een verontschuldiging te schrijven. Immers, iedereen die een bijdrage heeft geleverd aan dit proefschrift heb ik allang bedankt. Bedanken is niet zo erg moeilijk, verontschuldigen des te meer.
Na mijn AIO-periode in Groningen was er nog een restje proefschrift over dat geschreven moest worden. Niet eens heel erg veel, twee papers combineren tot een hoofdstuk en een conclusie en discussie schrijven. Dit restje duurde bijna vijf jaar. Ik was aan een andere zeer leuke baan begonnen, kreeg drie kinderen en verhuisde drie keer. Enige onderschatting van mijn kant was hier wel aan de orde. Ondanks de medewerking van mijn nieuwe werkgever bleef de tijd en concentratie om te schrijven toch beperkt. Ik wilde voorkomen (en ik vind dat dat in ieder geval voldoende gelukt is) dat ik in mijn dankwoord een verontschuldiging moest maken aan mijn gezin. Noor, Evi en Daniël, ik schrijf dit stukje in het weekend terwijl ik met jullie had kunnen spelen. Gelukkig kwamen opa en oma vandaag onverwacht langs.
Jarenlang sleepte ik de stukken die ik nodig had voor het laatste restje mee in een plastic tas van Albert Heyn. Om in weekenden bij “opa en oma” wat te kunnen schrijven. Toen ook die tas gaten begon te vertonen werd het tijd wat vaker de weekenden te benutten om echte vooruitgang te boeken. Met een vast recept van twee roombroodjes, twee bakjes volle roomyoghurt (kersen) van de AH en een flesje cola dat ik nooit opdronk ronde ik het proefschrift af in enkele zaterdag- en/of zondagmiddagen. Chocola en Cola light heb ik ook wel eens geprobeerd, maar dat werkt volgens mij alleen maar in uitzonderlijke gevallen. Mijn idee over bedanken is dat je dat zo snel mogelijk moet doen. Niet jaren later nog eens. Bovendien is bedanken een hachelijke zaak. Natuurlijk, iemand heeft iets voor je gedaan en dat is bijzonder en belangrijk. Het is echter niet goed in te schatten in welke mate de inzet van een ander een invloed heeft gehad op dit proefschrift. Een achteloze opmerking van iemand kan heel belangrijk zijn geweest in de ideevorming. Ik denk dat ik iedereen die betrokken is geweest al lang geleden heb bedankt. Maar ik besef me ook dat ik aan anderen nog niet verteld heb hoe belangrijk deze mensen zijn geweest.
Dit proefschrift is niet mijn individuele prestatie. Dus, genoeg over mij en wat ik voor mezelf heb gedaan, laten we het er over hebben wat anderen voor mij hebben gedaan!
Op een bijzonder warme dag in 2002 solliciteerde ik bij Karel Brookhuis, mijn promotor, naar een AIO-positie. Hij had vertrouwen in mij (vast omdat ik ondanks de enorme hitte vastbesloten was mijn jasje niet uit te doen) en samen ontwikkelden we plannen voor onderzoek. Hij gaf mogelijke richtingen aan, maar gaf me vooral veel vrijheid mijn eigen koers te bepalen. Op momenten dat ik het gevoel had vastgelopen te zijn wist hij me altijd weer terug te krijgen op de rode draad in het onderzoek. Door contacten die hij had gelegd konden we erg leuk onderzoek uitvoeren in de praktijk. Ik hoefde nooit lang te wachten op een reactie op mijn concept hoofdstukken. Karel heeft zich een zeer geduldig promotor getoond. Karel is gastvrij en plezierig in de omgang. Helemaal als Lena aanschuift.
Addie Johnson is lang tweede promotor geweest. Haar inbreng in de onderzoeksopzet van de studies in Hoofdstuk 4 waren van groot belang. Ik heb veel geleerd van haar werkhouding (ze reageerde nog sneller dan Karel op concepten), gedegen reacties op conceptversies en correcties op mijn Engels. Af en toe bij het schrijven in het Engels heb ik het gevoel dat ze over mijn schouder meekijkt of ik de bijwoorden grammaticaal goed schrijf.
Linda Steg heeft een grote invloed gehad op de theorievorming van mijn onderzoek. Het idee om de invloed van cognitieve ergonomie en de sociale psychologie op het keuzeproces te omschrijven via de informatie verwerkingstheorie van McGuire komt van haar (zie Hoofdstuk 2). Ik ging veel om met de AIO’s van Linda. Ik vermoed dat Linda af en toe vergat dat ik eigenlijk geen AIO van haar was. Ik kon altijd met vragen bij haar terecht, ze beoordeelde concept hoofdstukken (Hoofdstuk 1 en 2) en hielp mij op weg met ideeën voor onderzoek om de koppeling met de sociale psychologie te leggen. Daar nam ze veel tijd voor. Na ieder gesprek met haar had ik nieuwe ideeën en motivatie.
Dick de Waard gaf me veel praktische tips voor de opzet van mijn onderzoeken, hoe ze te verwerken, te rapporteren en te presenteren. Ik profiteer nu nog steeds van wat ik van hem geleerd heb. Als ik mijn vrienden en familie zou vragen wat zij vinden van Dick zouden ze hem de sociale norm vinden. Dick, dat je in de promotiecommissie zit betekent meer voor me dan je vermoed (is mijn inschatting).
Voorwoord iii
Talib Rothengatter was in de beginfase van het onderzoek betrokken en gaf nuttige tips over kansrijk onderzoek en het schrijven van artikelen. Helaas overleed hij begin 2009. Ik had graag met Talib, net als tijdens de koffiepauzes (in de middag), de degens gekruist over een van de stellingen.
Mijn promotiecommissie bestaat naast de Rector Magnificus en mijn promotor uit: Bert van Wee, Dick de Waard, Linda Steg, Wiebo Brouwer, Eric van Berkum en Serge Hoogendoorn (programmaleider AMICI). De korte tijd die er was om mijn proefschrift te beoordelen viel tijdens de zomervakantie. Ondanks dat hebben de commissieleden snel een oordeel geveld. Als AIO kom je niet veel buiten. De Gemeente Den Haag gaf me in twee opvolgende jaren de mogelijkheid om tijdens het vuurwerkfestival in Scheveningen te experimenteren met verschillende afbeeldingen op een Grafisch Route Informatie Paneel. Dankzij Toine Molenschot en Vincent van der Heijden heb ik erg leuk onderzoek gedaan. De praktijkproef geeft dit proefschrift een enorme meerwaarde.
Tijdens mijn AIO-periode deed ik zo’n 25 experimenten. Minder dan de helft heb ik gerapporteerd in dit proefschrift. Door het begeleiden van studenten bij onderzoek kon ik een aantal pilotstudies uitvoeren die later uitmondden in onderzoek dat in dit proefschrift is opgeschreven. Vele studenten van het vak “onderzoeksvaardigheden” werkten daar aan mee. Speciaal noem ik Foppe Wobbes, Jelmer Jeuring en Esther de Vries die hun masterthese uitvoerden bij me. Ik gebruikte de scriptie van Rosanne Rademaker als basis om één van de onderzoeken in Hoofdstuk 5 op te schrijven. Ilse Harms voerde het overgrote deel uit van de studies die gerapporteerd worden in Hoofdstuk 4. Dit deed ze met enorme inzet, flexibiliteit, zelfstandigheid, gezonde nieuwsgierigheid en nuttige tegenspraak. Ik ben dan ook niet verbaasd dat zij nu zelf een promotie onderzoek uitvoert.
Together with Katrin Dziekan I wrote a paper on travel information. The idea for this paper emerged during a conference in 2002 in Eindhoven. Our paper was part of her thesis and was published in a journal. I learned much from our fruitful discussions. During her visit to Groningen she made me realise how inspiring my working environment was. During my visit in Sweden and on other occasions she showed me the benefits of working hard. She never complains and sees the benefits in all situations.
Patrick van Beijnen was mijn contactpersoon bij OV9292. We hadden regelmatig contact over de mogelijkheden van reisinformatie en de manier hoe reisinformatie ingezet kon worden om de keuzereiziger te verleiden met openbaar vervoer te reizen. Ik heb Patrick helaas niet meer kunnen bedanken voor onze leuke en nuttige discussies. Ik kan hem ook niet meer vertellen wat een fijne vent hij was. Hij overleed in 2008.
Mijn dagelijkse werkzaamheden voerde ik uit in Groningen op de afdeling Experimentele en Arbeidspsychologie van de Rijksuniversiteit Groningen. Hoewel daar prachtig onderzoek wordt uitgevoerd is vooral de koffietafel en de niet werkgerelateerde activiteiten het noemen waard. Een dagelijkse welkome onderbreking van het werk. Ik leerde veel levenswijsheden van Berry Weijers (bijvoorbeeld: als het eten niet goed is klaag je daar niet op de avond zelf over, het zou anders de sfeer van de avond verpesten). Monicque Lorist had met een opmerking die ze vast zelf al weer vergeten is een grote invloed op een van de basisideeën in dit proefschrift. Van Pieter de Vries leerde ik hoe je een theezakje zonder te morsen uit een theekopje krijgt. Van Ben Mulder had ik tijdens mijn studie al erg veel geleerd, aan de koffietafel leerde ik door hem dat sommige mensen echt verstand van voetbal hebben. Door Jurjen van der Helden kreeg ik het vermoeden dat dit ook andersom kan zijn. Frank Steyvers
merkte eens op dat je beter eerst je proefschrift kunt afmaken en dan pas aan kinderen moet denken. Ik twijfel of het waar is, maar heb laatst voor de zekerheid die tip aan iemand meegegeven. Van Mattie Tops leerde ik dat in bijna iedere zin (maar soms heel diep) een kans ligt op een totaal andere uitleg van de zin. Maarten Boksem bezat het talent om naast lekker ouwehoeren (en dat kon Jurjen ook) ook prestaties neer te zetten. Jan Willem Bolderdijk wist woordgrappen te waarderen! Verder was het altijd gezellig met Arjen Stuiver, Janet Veldstra, Ben Lewis-Evans, Ebru Dogan, Annemarie van Brussel en een aantal mensen die ik misschien vergeet. En natuurlijk Wokje, Judith en Geertje, maar daarover later meer.
Enige lichte paniek is nu ontstaan bij Ans van Rijsbergen omdat zij niet genoemd is bij de koffietafel van E&A. Maar natuurlijk vergeet ik jou niet Ans! Jij verdient je eigen alinea! De koffietafel en andere activiteiten buiten het werk bestaan dankzij jou Ans! Je bent de lijm van de afdeling. Je zorgt voor gezelligheid, hebt aandacht voor iedereen en werkt erg efficiënt. Daarnaast ben je een hartelijke, warme vrouw met humor!! Met deze woorden is de lichte paniek omgeslagen in zware paniek: meent hij dat nou of neemt hij mij in het ootje? Ans, het is van harte gemeend. Over vier dagen mogen we stemmen. Ik mis de discussies met jou over wel of niet stemmen, en zo ja, waarop of juist waartegen!
Ik deelde mijn kamer met Judith de Groot. Het werd al snel gezellig, vooral toen ook Wokje Abrahamse en Geertje Schuitema onze buurvrouwen werden. Uitdrukken hoe ik die tijd met hen heb ervaren kan ik in vier woorden afdoen: “in één woord fantastisch”. Daarvoor was het ook best leuk met Maarten, Mattie en Jurjen, maar (om met Maartens woorden te spreken) “gewoon anders”. Het is jammer dat de strenge regels in Delft niet toestaan om drie paranimfen te hebben. Deze drie dames waren bereid te lachen om mijn woordgrappen. Niet omdat ze leuk waren, maar omdat het leuk en gezellig is om te lachen. Andersom was ik bijvoorbeeld bereid om aan een van hen uit te leggen wat de woordgrap was, en mijn vrouwelijke kant niet te verbergen. Met hen was iedere werkdag leuk, we hadden leuke avonden, lazen bij mooi weer buiten in de oude Hortustuin artikelen, hadden barbecues (vegetarisch), beleefden weekenden in het buitenland, gingen samen naar congressen, films, enzovoort. Oh ja, en natuurlijk ……. Dalmutsie!
Geertje, je hebt het talent heel lang ergens tegen aan te hikken, maar op het juiste moment precies het goede te doen. Jouw integratiestrategie toen je samen met Wokje op “mijn” afdeling terecht kwam (en die je later ook in Aberdeen en Arhus toepaste) werkte uitstekend. Het heeft mijn AIO-periode enorm verrijkt en zoveel leuker gemaakt. Als ik aan jou denk dan zie ik ons weer rennen over het station van Londen Waterloo (denk ik) om de trein richting kanaaltunnel te halen. De deuren sloten direct na ons. En jaren later reden we met hoge snelheid over de duitse autobahn om jou op tijd bij de nachttrein richting Zurich te krijgen. Gewoon omdat je als bewust openbaar vervoer reiziger weigert een trein eerder te nemen om rekening te houden met vertragingen. Een trein moet gewoon op tijd rijden vind jij. Het levert in ieder geval leuke herinneringen op! Zullen we doen dat ik vanaf nu controlegroep ben? “Nothwithstanding the fact”, komt een aantal keren voor in dit proefschrift. Ik weet eigenlijk niet precies wat het betekent. Wokje, die woorden zijn een eerbetoon aan jou. Omdat jij ze leuk vindt. Jij haalde een enorme last van mijn schouders toen je aanbod het Engels in mijn hoofdstukken te corrigeren. Daardoor kon ik zorgeloos schrijven. Ik snap niet wat voor plezier iemand kan beleven aan de Engelse taal. Maar als ik iemand een plezier doe met mijn gebrekkige engelse teksten: “be my guest”. Wokje, jammer dat je zo vaak en zo ver weg verhuist. Ik heb veel leuke muziek via jou leren kennen en ik luister nog regelmatig naar je verzameling vrolijke muziek. Eigenlijk vooral als ik na muziek die ik als vrolijk beoordeel
Voorwoord v
aan iets rustigers toe ben. Je bracht rust in ons groepje. Wokje kan zonder hulp een kubus oplossen en maakt onbewust woordspelingen, leuk he?
Judith, mijn kamergenoot zijn is niet makkelijk. Ik klaag veel en vooral over futiliteiten, vertel oninteressante anekdotes en maak slechte woordgrappen. Je had er geduld voor. Je sprak me tegen als ik gelijk had en gaf me gelijk als ik er naast zat. En, misschien wel belangrijker: je drukte me af en toe met mijn neus op de feiten als je vond dat ik me wel erg makkelijk van iets afmaakte. Het was altijd beregezellig met jou. Tijdens werk en buiten het werk. Je waardevrije opstelling naar anderen zijn voor mij een goed voorbeeld geweest. En, je maakte me enthousiast voor klimmen. Ik drink niet vaak cappuccino, maar als ik er een neem is dat op donderdagmiddag om 1 uur. En dan zing ik er zacht een liedje bij.
Jammer dat jullie alle drie naar het buitenland zijn verhuisd. Ik hoop dat mijn promotie een aanleiding is om weer eens een gezellige avond “met zijn allen” te hebben. Marieke en Melle, komen jullie dan ook? Ik neem Jacqueline mee. Jullie waren altijd erg geduldig als we langdurig spraken over ons werk en collega’s in jullie bijzijn.
Sinds 2008 werk ik als adviseur bij Goudappel Coffeng. Twee van de beste woordgrappen1 die ik ken werden matig ontvangen, maar verder heb ik het erg naar mijn zin. Ik heb mijn onderzoek naar reisinformatie voortgezet, heb me ontwikkeld als expert in filemijden en samen met mede gedragskundigen Marc de Haan en Lotte van den Munckhof pas ik de laatste inzichten in menselijk gedrag toe op verkeer en vervoer. In de volle breedte van ons bedrijf. Mijn hoofd, Wim Korver, wist dat een proefschrift afronden naast je reguliere werk uiteindelijk zowel op werk als privé kan gaan wringen. Hij creëerde daarom zonder dat ik erom hoefde te vragen mogelijkheden zodat ik in werktijd aan mijn proefschrift kon werken. Zonder hem was mijn proefschrift waarschijnlijk ook wel afgekomen, maar heel veel later. Wat ook erg hielp waren de woorden van directeur Jaap Benschop: “als je zelf geen plan hebt, dan word je het plan van een ander”. Met deze woorden in het achterhoofd ben ik aan de laatste loodjes begonnen. Mijn collega’s Marc Stemerding en Peter van der Mede namen de moeite het manuscript te lezen en te adviseren over de inhoud. Dat leidde tot een sterke verbetering van de discussie. Gewoon door het eerst kleiner te maken en daarna weer groter. Dat kleiner maken is overigens ook een kwaliteit van Marga Mulder. Zij corrigeerde vlak voor het drukken de Nederlandse samenvatting. Met een snelheid die nooit went.
Vanuit onderzoeksschool TRAIL regelde Conchita van der Stelt alle formaliteiten. Ze gaf op een erg prettige manier feedback over de opmaak van het “boekje”. Dankzij haar is de opmaak netjes en consequent. Conchita, ik weet niet hoe je er uit ziet, zelfs niet hoe je stem klinkt, maar als dank geef ik je de kans mijn 500ste contact op LinkedIn te worden. Ik heb je daar zojuist een uitnodiging voor gestuurd.
Carel en Wil zijn mijn ouders. Ik ben de jongste van vijf kinderen en mijn ouders hebben altijd erg hun best gedaan voor ons allemaal. Zij gaven mij goede normen en waarden mee. Ze zijn bescheiden en cijferen zichzelf graag weg. Als je aan een matig betaalde AIO-baan begint is het fijn om een familie achter je te hebben staan. Als u ze ziet bij mijn verdediging of op de receptie, geef ze gerust een schouderklopje. Het valt niet mee voor hen die andere vier
1
Oordeelt u zelf:
Wat is de afkorting van de Hogeschool voor Humor en Hilariteit? (Kees Torn). In het verkeer traffic het nooit. (vrij naar Kees Torn).
kinderen. Ik heb twee broers (Freek en Jan-Jaap) en twee zussen (Hester en Marjolijn). In mijn presentaties over gedragsverandering heeft u hen of hun auto’s wel eens voorbij zien komen. Ik geniet enorm van hen, mijn zwagers, schoonzussen en neefjes en nichtjes. Dus Freek, Astrid, Maaike, Maurits, Hester, Ronnie, Marijke, Loes, Jeroen, Lotte, Jan-Jaap, Engelien, Iris, Tamar, Marjolijn, Frank, Jarno: ik geniet van jullie!
Jacqueline, ik draag dit proefschrift op aan jou en onze kinderen, Noor, Daniël en Evi. De afgelopen jaren waren enorm druk met verhuizingen en de geboorte van onze kinderen. Onze beperkte gezinstijd heb ik zo weinig mogelijk maar toch onvermijdelijk ingezet om dit proefschrift af te ronden. Daarmee werd de last op jouw schouders groter in een toch al vreselijk drukke periode! En ik realiseer me dat het niet prettig was dat juist omdat ik in de weekenden niet aan mijn proefschrift werkte het proces zo lang duurde. Je hebt me fantastisch ondersteund! Dank je wel, ik houd van jou! Evi, Daniël en Noor, ik hoop dat jullie ooit dit dankwoord nog eens lezen. Ik houd ontzettend veel van jullie, en geniet ervan om jullie te zien ontwikkelen. Het is heerlijk om ’s avonds thuis te komen bij drie kinderen die me enthousiast begroeten.
Veel mensen vroegen regelmatig voorzichtig hoe het er voor stond met mijn “P”. De prijs voor de subtielste vraag gaat naar Mark Dekker (weer eens klimmen?) met zijn vraag: “Hoe gaat het eigenlijk met Karel?”.
Matthijs Dicke-Ogenia Deventer, 8 september 2012
vii
Contents
Voorwoord i
1
Congestion and information provision... 1
1.1 Mobility ... 1
1.2 Congestion ... 2
1.3 Mitigating congestion ... 2
1.3.1 Efficient use of travel network ... 3
1.3.2 Travel Demand Management ... 5
1.4 Information systems ... 6
1.4.1 Advanced Traveller Information Systems... 6
1.4.2 Contemporary ATIS ... 7
1.4.3 Roadside information ... 8
2
Travel information to mitigate congestion ... 13
2.1 Diversion rate ... 13
2.2 Persuasive communication ... 15
2.3 Cognitive ergonomic guidelines... 17
2.3.1 Conspicuity... 17
2.3.2 Legibility ... 18
2.3.3 Comprehensibility ... 19
2.3.4 Credibility... 19
2.4 Social psychological principles ... 20
2.4.1 Habit ... 20
2.4.2 The elaboration likelihood model ... 22
2.4.3 Attitudes ... 23
2.4.4 Utility maximisation... 24
2.5 Recommendations for the design of travel information ... 26
2.6 Designing an FCIP – The TravelGuide project ... 31
2.7 Dissertation outline... 32
3
Display of a route map... 35
3.1 Introduction ... 35 3.2 Study 1... 40 3.2.1 Method ... 40 3.2.2 Results ... 41 3.2.3 Discussion ... 43 3.3 Study 2... 44 3.3.1 Method ... 44 3.3.2 Results ... 44 3.3.3 Discussion ... 46 3.4 Study 3... 48 3.4.1 Method ... 48 3.4.2 Results ... 50 3.4.3 Discussion ... 57 3.5 General discussion... 59
4
Presentation of congestion information ... 61
4.1 Introduction ... 61
4.1.1 Methods for displaying congestion ... 61
4.1.2 Using colours to indicate congestion ... 63
4.2 Study 1: Expert opinions on the use of colour ... 65
4.2.1 Method ... 65
4.2.2 Results ... 66
4.2.3 Conclusion... 68
CONTENTS ix
4.3.1 Introduction ... 69
4.3.2 Method ... 69
4.3.3 Results ... 73
4.3.4 Discussion ... 76
5
Usability, safety and route choice aspects of different styles of
en-route travel information ... 79
5.1 Introduction ... 80
5.2 Travel information, information processing and safety ... 80
5.2.1 Physical requirements ... 81
5.2.2 Information processing requirements... 81
5.3 Support of information processing while driving... 83
5.3.1 Working memory ... 83
5.3.2 Auditory versus visual route guidance ... 84
5.4 Aim of the present studies ... 84
5.5 Study 1: Auditory and visual in-car information systems ... 85
5.5.1 Optimal travel information... 85
5.5.2 Research questions and hypotheses... 85
5.5.3 Method ... 85
5.5.4 Design and procedure... 87
5.5.5 Independent variables... 88
5.5.6 Dependent variables ... 90
5.5.7 Results ... 92
5.5.8 Discussion ... 103
5.5.9 Conclusion... 104
5.6 Study 2: In-car travel information or travel information over a road... 106
5.6.1 Method ... 107
5.6.3 Independent variables... 108
5.6.4 Dependent variables ... 108
5.6.5 Results ... 110
5.6.6 Discussion and conclusion ... 124
6
Graphical presentation of travel information: the use of Full Colour
Information Panels ... 127
6.1 Abstract... 127
6.2 Introduction ... 128
6.2.1 Route map to the FCIP ... 129
6.2.2 Colours to indicate congestion ... 130
6.2.3 Readability and legibility of information displayed on an FCIP ... 131
6.3 Method... 132
6.4 Results ... 134
6.5 Discussion... 136
7
Conclusion and discussion... 139
7.1 Introduction ... 139
7.2 Ergonomic issues... 141
7.2.1 Display of a route map ... 141
7.2.2 Display of redundant congestion information ... 144
7.2.3 Display of travel times ... 146
7.2.4 Amount of information... 147
7.3 Behavioural change ... 148
7.3.1 Small target group ... 148
7.3.2 Willingness to change plans during the on-trip stage ... 149
7.3.3 Effects of reducing uncertainty and increasing positive attitude towards public transport 149 7.3.4 Conclusion on behavioural change, recommendations ... 150
CONTENTS xi
7.4.1 Conclusion with respect to traffic safety... 154
7.5 General guidelines for the provision of travel information ... 154
7.5.1 GRIP or DRIP?... 154
7.5.2 Guidelines... 155
7.6 A better use of the travel network?... 157
References ... 159
Summary ... 169
Samenvatting ... 177
About the author ... 185
Publications, conference proceedings and research reports on travel
information by the author ... 187
1
1
Congestion and information provision
1.1
Mobility
Mobility is an important social need and prerequisite to economical growth. Mobility enables us to be involved in a wide range of (leisure) activities, social interactions, work, and business. As a result, people have a strong urge to travel and to try and maintain their levels of mobility. Evidence for this is provided by the law of constant travel time and trip-rates2 (Hupkes, 1982). This law assumes that the average number of trips and the travel time that individuals are willing to spend tends to remain stable over time. That is, travel time saved for one trip is generally used to make an extra trip. As a result, faster means of travel do not necessarily result in less travel time, rather, it results in greater distances travelled.
The demand for mobility continues to increase as a result of various socio-demographic, cultural, and economic factors. For example, in the past two decades women have taken a much more active role in the workplace, which not only has resulted in an increase in the number of women who drive, but also in the number of multi-vehicle families. Moreover, members of double-income families do not necessarily move when one of the household members acquires a job in another area, resulting in an increase in the number of people commuting and hence the distance travelled, particularly during peak hours.
Demographic developments have also helped increase the demand for mobility. As a result of an increase in population size, people nowadays live further from their work. Between 1950 and 2007, the number of inhabitants in the Netherlands increased by 61.3% from 10.0 million to 16.4 million. Furthermore, car ownership in the Netherlands increased by 25.2% from
5.7 million in 1996 to 7.1 million in 2006 (CBS, 2007). Estimates indicate that car ownership will increase even further, by 40% to 8.9 million in 2020 compared to 2000 (Verkeer en Waterstaat (2004).
A cultural factor resulting in an increase in demand for mobility includes an increase in the number of single-parent households and an increase in the number of double-income families. In single-parent households more tasks have to be performed by fewer persons. Working, shopping, and bringing children to day care or to school is most efficient if trips are combined. The car is a preferred mode for combining trips (Batenburg & Knulst, 1993). When people travel to work by car, trips that otherwise would have been made by bike or on foot are also made by car. Although, total mobility will not increase in this example, car use will increase. As a result of cultural changes, more women possess a driving licence and car (Van Knippenberg et al., 1989). This results in more cars per household. In 1990 46.3% of the women had a driving license. In 2005 this percentage had increased to 55.8% (CBS, 2007). Finally, economic factors that have increased the demand for mobility involve increased wealth. Hence, more households can afford one or more cars, and can also afford to spend more money on travel costs. As a result, not only more activities can be undertaken, but also the area in which activities are accessible has become larger (Batenburg & Knulst, 1993; Orfeuil & Salomon, 1993; Pucher, 1999).
1.2
Congestion
The increasing needs and desires for mobility have the unpleasant side effect of increased congestion. Congestion in traffic networks results when traffic demand exceeds the available capacity of a road network. Two types of congestion are generally distinguished. Congestion that occurs regularly (e.g., during rush hours) and at specific locations due to the fact that mobility demand is structurally higher than the supply of road infrastructure, is referred to as
recurrent congestion. Congestion as a result of temporary disruptions that diminish road
capacity during a certain period of time is referred to as non-recurrent congestion. Temporary disruptions can, for example, result from vehicle breakdowns, accidents, road works, bad weather, or large public events. It is estimated that in the Netherlands around 80% of congestion is recurrent and around 20% is non-recurrent (Ministerie van Verkeer en Waterstaat, 2004; AVV, 2005). From 2000 to 2020, the loss of travel time during peak hours will double. Additionally, loss of travel time during off-peak hours is expected to increase (Verkeer en Waterstaat, 2004). Overall, the average traveller is expected to spend more time stuck in traffic congestion.
Congestion on road networks increasingly causes severe problems in and around large cities. Consequences of congestion include an increase in travel time and travel costs, environmental costs, economic costs, increased energy use and decreased economic growth, reduced travel time reliability, and reduced quality of life. Without a change in the traffic network, congestion will become more severe: more roads will become congested, congestion will occur more frequently during the day, and the average length of traffic jams will increase. Therefore, mitigation of congestion is deemed necessary.
1.3
Mitigating congestion
In the Netherlands, congestion is particularly prevalent in the western, more densely populated, part of the country. The infrastructure is not sufficient to serve the growing desire for mobility. The current policy is that mobility should not be sacrificed to mitigate
Chapter 1 - Congestion and information provision 3
congestion (Verkeer en Waterstaat, 2004). Discouraging car use in favour of travelling by public transport or by bike seems a suitable measure. However, the many advantages of private car use make it very difficult to encourage travellers to reduce car use (Steg, 1996). A car is fast, comfortable and flexible in use. As a result, most households own one or more cars. It has been noted that owning a car will almost automatically lead to car use (Banister, 1978), also for trips for which the car may not be an optimal choice in terms of costs, travel time, and risk of congestion. Car use fits a need for individualization, a need for freedom and privacy, and a need for power and control that is valued as more important than disadvantages like congestion and costs of car use (Steg, 1996). Dutch governmental policies tend to encourage car users to use the travel network more efficiently. For example, by choosing alternative (non-congested) routes, using public transport or travelling outside peak hours. For these options to take effect, changes in behaviour are necessary.
In the next section, it will be argued how and why a more efficient use of the travel network will help mitigate congestion. Furthermore, the reasons why psychological strategies aimed at behaviour change, such as information provision, may encourage a more efficient use of the travel network. Furthermore, the possibilities information systems can provide to facilitate an effective provision of travel information will be shown.
1.3.1 Efficient use of travel network
As long as the capacity of a travel network is sufficient to process current and future traffic, obviously a change in travel behaviour is not necessary. However, in situations where congestion may occur, the travel network should be expanded or used more efficiently. In general, four important options exist to use the travel network more efficiently. These options include: making the trip entirely by car, making the trip entirely by public transport, making a combination of travelling by car and public transport, and change the need to travel for a trip. Of course, other options may be possible. For example, travelling by bike may be a good substitute for travelling by car or public transport for short trips. However, for the purpose of this thesis, the four options mentioned are the most important. They will be explained in the remainder of this section.
Making the trip entirely by car
An optimal distribution of cars over the available routes is possible. If a city can be reached via two routes by car, traffic flow on each route will be less dense when traffic is well balanced over both routes. When one route is the optimal route, as defined by travel time or severity of congestion, most travellers may choose this route. As a result, that route will become more congested and the other route may become the optimal route. In turn, more travellers may choose that route. Theoretically, this may lead to an optimal distribution of cars over available routes. The network flow pattern will approach equilibrium when travellers repeatedly choose the optimal route. However, this will only work if travellers are able and
willing to make an optimal route choice based on accurate information about traffic
conditions.
Furthermore, an optimal distribution is only possible when the traffic network has some spare capacity. Congestion may be so severe that an optimal distribution of cars over available routes cannot be achieved. In such cases, other travel modes than the car become important.
Making the trip by public transport
A better distribution of vehicles over routes can be accomplished by providing and promoting the use of public transport services. If car use is substituted by the use of public transport, the number of vehicles on a route will be reduced. As a result, congestion may be lower
compared to the situation without public transport. Travel time in public transport for parts of a journey where congestion is likely to occur may be considerably shorter than travel time for car use. However, public transport does not provide door-to-door service. Furthermore, public transport is not as popular as car use (Steg, 2003b). As a result, the vital link in a public transport system is the part of the trip that is not covered by public transport itself. It includes the trip to arrive at the public transport service or the trip at the end of the public transport journey to the final destination (access and egress) (Krygsman et al., 2004). These first and last steps of the journey are often relatively the most time consuming parts as they are (often) not covered by public transport services. In contrast, the car offers excellent door-to-door mobility. However, the drawbacks of car use may in some cases start outweighing the advantages. Parking fees are increasing and available parking spaces are decreasing. Furthermore, public transport companies offer good alternatives for door-to-door mobility. In the Netherlands the national railway company offers cheap rental bikes for travelling between a train station and the destination of the traveller. Renting this bike is quick and easy. The number of trips made by means of this rental bike in 2008 has increased by 46% compared to 2007 (OV-fiets, 2009).
Combining travel modes
An optimal travel time may be achieved by making a combination of car and public transport. Such combinations involve travelling by car for the first part of a journey and switching to public transport for parts of the journey where the car is slower or less than ideal than public transport. The last part of the trip from public transport to the destination may be made by foot, (rental) bicycle, taxi etc. Logically, making combinations of travel modes is not beneficial for all journeys. The destination should be easily accessible by the public transport service.
Making these combinations for trips in a journey is referred to as chain mobility. Chain
mobility, as an alternative to exclusively travelling by car, entails making combinations of
transport systems within one journey and offers the traveller door-to-door mobility. It combines individual transport with collective transport. For example, a traveller may travel by bicycle or car to a train station. The journey may be continued by train and for the last part of the journey a bus, taxi, or rental bike may be used. When the different chains in the trip are connected optimally, it may - theoretically - result in an optimal travel time, particularly in case of congestion. The travel network is used optimally and the traveller’s experience of freedom is less affected as compared to exclusively travelling by public transport.
A specific example of chain mobility is the use of Park and Ride (P+R) facilities. P+R facilities are generally built in the periphery of urban areas that attract much traffic. Travellers can park their vehicles outside the congested area and switch to public transport for the remainder of their journey. The use of P+R facilities may help to avoid congested roads while providing easy access to city centres or other activity centres.
P+R facilities have three advantages for travellers. First, in case of congestion, the use of the P+R facility may reduce travel time. Public transport services like the tram, train, and metro have their own infrastructure and bus services can often travel via a bus lane separate from other traffic. As a result, public transport services can avoid traffic jams. Second, P+R facilities offer a solution for limited parking capacities in large city centres. Third, parking costs at P+R facilities are lower compared to parking costs in city centres.
Chapter 1 - Congestion and information provision 5
Changing the need for travelling
Besides changing the way of travelling, a traveller can choose to travel outside peak hours, or not travel at all. For example, a traveller can work at home or can start working at home and travel to the office at a later time (to avoid congestion).
As long as congestion occurs, the travel network is apparently not used efficiently. The travel options mentioned in this paragraph assume a change in travel behaviour. As mentioned earlier, it is very difficult to change the behaviour of car drivers. For example, the changes in route choice and mode choice mentioned in this section assume a benefit for the travel network when there is an optimal distribution of travellers within a travel network. However, a discrepancy between what would be optimal for the travel network and what would be optimal for the traveller may exist. The traveller may have other reasons for choosing a specific route or travel mode than travel time, severity of congestion, or travel costs. Amongst others, reasons may include: a preference for a fixed route, a positive or negative attitude towards public transport, unfamiliarity with alternative routes or travel modes, beliefs that congestion on one route will lead to congestion on another route, or distrust in traffic information. Furthermore, travellers may not realise their chosen route is not optimal. All the options mentioned in this paragraph assume a change in travel behaviour on the part of the traveller. Therefore, in order to have an effect on the efficiency of the travel network, measures should be taken that change travel behaviour.
1.3.2 Travel Demand Management
A change in travel behaviour may be induced via Travel Demand Management (TDM) measures. TDM measures can target behaviour via structural or psychological strategies (Steg, 1996; Steg, 2003a). Structural strategies (Messick & Brewer, 1983) aim to change situations in which decisions are made so as to make desired behaviour more attractive and undesired behaviour less attractive. A first type of structural strategy involves the provision of physical alternatives and changes. For example, changes in infrastructure in order to improve the quality of public transport or an increase in road capacity by building more roads. A second type of structural strategy involves financial-economic stimulation. The aim of financial-economic stimulation is to make owning or driving a car less attractive (i.e. more expensive) or to make alternative means of transport, such as the bicycle or public transport, more attractive (e.g. by making them cheaper). A third type of structural strategy involves legal regulation, adopted by government or local councils in order to reduce car use. Examples of legal regulation include the prohibition of motorized vehicles in city centres and reducing speed limits.
Psychological strategies aim to influence people’s perceptions, beliefs, attitudes, values, and norms (Steg, 2003a). Psychological strategies involve the provision of information, education, arguments, examples of “good” behaviour, and prompts aimed at increasing travellers’ knowledge (e.g. of alternative routes or travel modes), enhancing their awareness (e.g. of problems or alternatives), affecting their attitudes and strengthening their inclination and possibilities to adopt other kinds of behaviour (e.g. public transport or non-motorised transport) (Steg, 2003a). For example, informing travellers about alternative routes or alternative travel modes may influence travel behaviour and persuade car users to avoid congested routes or change travel mode.
Each strategy has specific advantages and disadvantages. Structural strategies are generally more effective than psychological measures insofar as they actually change positive and negative consequences of behavioural options and can actually reduce the relative attractiveness of car use during congestion compared to alternative travel modes. However,
structural strategies are not easy to implement. In general, the more effective the measure, the lower public acceptability judgements; measures that are considered to be acceptable by the public are not necessarily effective in terms of reducing congestion (Steg. 2003a). Public support is an important precondition for implementing policies that restrict individual car use (Schlag & Teubel, 1997; Steg, 2003a).
Psychological strategies are generally accepted by the public because they do not affect freedom of choice of the traveller. For example, receiving information does not mean that you have to comply with the information. Furthermore, psychological strategies are less expensive and less difficult to implement than structural strategies. Therefore, psychological strategies are an attractive strategy to mitigate congestion. An important question is how such strategies can be used effectively to mitigate congestion problems. This will be discussed in Chapter 2. In general, neither structural strategies nor psychological strategies are believed to be optimal to mitigate congestion when applied in isolation (Maibach et al., 2009; Steg & Buijs, 2004). Psychological strategies can support the application of structural strategies. For example: A structural strategy such as building a Park and Ride facility will not guarantee that travellers will use the facility. Travellers may be reluctant to use the facility because information on, for example, availability, costs, safety, or departure times of public transport are unclear. In such cases, travellers need to be informed by means of psychological measures. Information should be provided that informs the traveller on relevant aspects of the Park and Ride facility. Psychological strategies can strengthen the effect of structural strategies and are therefore an important prerequisite to promote the efficient use of the travel network.
In this thesis, the focus is on the psychological strategies for travel information over a motorway. The information provided is aimed at affecting route choice or mode choice. For a more efficient use of the travel network information is needed about which route and which travel mode is optimal for a particular travel network and subsequently for the traveller in that specific situation.
1.4
Information systems
Traffic flows in a network can be brought close to an equilibrium if adequate information is provided to travellers (Iida et al., 1992). For example, by providing information to the traveller on traffic conditions for available routes or informing the traveller on the benefits of a travel mode, the traveller may be able to make a better informed route or mode choice. As a result, the traveller has information that may help to travel more efficiently. Therefore, travel information must be brought to the travellers’ attention.
1.4.1 Advanced Traveller Information Systems
One way to provide such information is by making use of Advanced Traveller Information Systems (ATIS). ATIS is a generic term to describe all telecommunication systems that provide static or dynamic information on traffic conditions, time schedules for public transport services, delays as a result of accidents, parking availability, road works, congestion, route guidance, weather conditions, special events, and more.
ATIS can help the traveller to make better informed decisions that may result in a more efficient use of the travel network (Peirce & Lappin, 2003; Adler & Blue, 1998; Mascia, 2003). ATIS offer information to avoid or at least prepare for congestion. For the individual, the ability to avoid congestion by making different travel choices may result in reduced travel time, reduced travel costs, and improved safety. When other travel choices are not viable or
Chapter 1 - Congestion and information provision 7
there do not appear to be better options, ATIS can at least reduce travellers’ stress by providing information on the severity of the road conditions. Even a reduction in travel time uncertainty can be achieved (Mascia, 2003). For example, a commuter used to travel by car who receives information on non-recurrent congestion on his or her daily route to work may decide to travel by another means of transport than initially intended, change his or her departure time, travel via another route by car, or may not change at all. ATIS provides benefits for the individual traveller and the travel network as a whole (Levinson, 2003; Schofer et al., 1993; Emmerink et al., 1995).
Travel information provision through ATIS is generally classified as pre-trip or en-route information. This classification refers to the moment at which travel decisions are made. During the pre-trip stage, decisions on modality, route, and departure time are made. During the en-route stage, decisions are made about what route or modality to take when something happens that provides a reason to change travel plans (e.g., congestion or weather changes). Sometimes post-trip information is appended to the classification of travel information through ATIS. Post-trip information is provided after a trip and enables the traveller to evaluate the trip or compare the trip with facts on alternative trips that could have been chosen. The post-trip information facilitates learning and may have an effect on future choices.
Until recently, information provided in each stage of travelling was mainly static information. Furthermore, when dynamic information was provided it was not personalized. Information during the pre-trip stage for public transport users included, for example, timetables for public transport. These were published on paper or by means of computers. The public transport traveller had to look up a departure time and arrival time by means of time tables. As a result, information on the schedules for public transport was provided. However, information on delays or recent changes was not available. Information for car users was provided via radio, television, teletext, and newspapers. This information could be used during the pre-trip stage and en-route stage. However, it was provided with a substantial delay. Furthermore, these devices provided information only on the most congested routes. For other, less congested routes no information was provided. Travellers were not able to find information by themselves. As a result, this information was not easy to use in the pre-trip and en-route stage. 1.4.2 Contemporary ATIS
Due to technical developments accurate travel information can now be provided for the whole travel network and without considerable delay. Furthermore, the traveller has the opportunity to obtain information at any time. Since the Internet is widespread and mobile devices with or without UMTS (Universal Mobile Telephone System) are introduced, accessibility of travel information has improved considerably. Handheld computers such as the Personal Digital Assistant (PDA) can connect to the internet and enable the user to ask for information on traffic conditions. The mobile phone provides the same service and enables the provision of information via short message services (SMS). These devices have improved travel information provision during the pre-trip and the en-route stages and offers possibilities to provide personalized, dynamic travel information. As a result, ATIS is currently not limited to information provision at a certain location. Travel information currently may be available everywhere, depending on the location of a personal telecommunication system.
An example of travel information provision by means of ATIS that is usable during the pre-trip stage is the provision of camera shots made at roads that are often congested. As a result, traffic conditions can be viewed in real time on the Internet. Another example is provision of information on traffic conditions due to widespread use of the Internet. Particularly,
estimations on development of congestion in an area can be published on the Internet with suggestions for alternative routes or travel modes. As a result of accurate information, a traveller may change route, travel mode, departure time, or even cancel a trip.
The introduction of Global Positioning Systems (GPS) and Graphical Information Systems (GIS) has resulted in a tremendous improvement of travel information provision during the en-route stage. These systems enable information providers to locate the travellers’ position. Information on traffic conditions in the area where the traveller is can be provided without providing redundant information (e.g. about locations the traveller has not planned to travel to). Furthermore, hand held computers and mobile phones offer the opportunity to provide personalised information that is not only based on the location of the traveller but also adapted to preferences and needs of the traveller. Personal preferences and needs can be stored in the personal devices.
1.4.3 Roadside information
Although the use of in-vehicle telecommunication is rising, it is still not used by the majority of travellers. ATIS are mainly used by highly educated men with above average incomes (Petrella & Lappin, 2004), professionals (Emmerink et al., 1996; Hato et al., 1999), and travellers who also use other telecommunication devices (Polydoropoulou & Ben-Akiva, 1999; Yim et al., 2004). Therefore, ATIS should not be limited to in-vehicle devices during the en-route stage. Roadside information is required as well. Roadside ATIS provides information on current road traffic conditions, information on the road itself, and on alternative routes or modes. ATIS can inform travellers about near-real-time roadway conditions, and this may influence short and intermediate-term travel choices (Schofer et al., 1993).
En-route information has the drawback that it is consulted during a demanding activity (i.e. driving). Traffic conditions (e.g. other traffic participants) determine the amount of attention a traveller can give to the information. For in-vehicle devices the problem is smaller than for roadside information. In-vehicle devices enable the traveller to wait for better traffic conditions to assimilate the information. Despite the risk that the traveller will consult the information too late, it enhances safety and the probability that the message is well processed. However, for roadside information the traveller has in general only one chance to read the information. In general, a traveller has around four seconds to read a traffic sign given a speed of 100 km/h (Roskam, 2002). In conditions with congestion the travel speed is lower and time to read the sign is longer. Yet, travel information should be readable under conditions without congestion.
Furthermore, travel time for each alternative must be provided to enable the traveller to make a well informed route or mode choice. For this purpose, dynamic travel information must be provided to the traveller under both normal conditions and conditions that deviate from normal. Dynamic travel information under normal conditions (i.e. without congestion) indicates that traffic flow is measured and information is available. As a result, it can reduce uncertainty about traffic conditions and prevent risk-aversive travellers to take unnecessary detours. Dynamic travel information under other conditions than normal (e.g. congestion) can provide information on deviations to the travellers and subsequently alert them to consider alternative routes or travel modes that may be optimal.
Several devices are feasible and/or available for roadside ATIS. Variable message signs (VMS) positioned on the road-side or on a gantry over a road, provide information uniformly to all drivers about the current traffic situation on that road. This may concern, for example,
Chapter 1 - Congestion and information provision 9
information related to road hazards, traffic conditions, public transport options, and parking availability. The advantage of a VMS is that information can be displayed, changed or removed based on dynamic information provision. However, the information that can be displayed on a VMS is limited to alphanumeric text. An example of a VMS is displayed in Figure 1.1.
Figure 1.1: an example of a VMS. This VMS is also referred to as a DRIP (Dynamical Route Information Panel). This VMS is located over the N44 in The Hague, the Netherlands. The VMS provides dynamic travel times for two routes. In case of congestion the VMS indicates whether the congestion is expected to increase or decrease. A “+” sign next to the travel time indicates increasing congestion levels while a “-“ sign indicates decreasing congestion levels.
A more sophisticated system compared to VMS systems is the Graphical Route Information Panel (GRIP). Unlike conventional VMS, the GRIP is not restricted to text. These panels provide dynamic traffic information graphically and offer the opportunity to display a simplified map of the road network, including the position of traffic congestion (Alkim et al., 2003). Compared to VMS, these panels can provide more information which is easier to understand. However, the map of the road network can not be changed. An example of a GRIP is displayed in Figure 1.2.
In the next-generation of GRIPs, the Full Colour Information Panel (FCIP), the presentation of the map of the road network can be adapted at any time. The FCIP displayed in Figure 1.3 is six metres long and three metres high. The designers of travel information can benefit from the new features offered by the FCIP. It allows a display of any kind of text, graphical representation and combinations thereof. These features offer the opportunity to display route maps, text combined with symbols, the position of traffic congestion (colour coded according to severity), or any other representation the designer may wish. In this way, complex information can be provided in a way that makes it easier to process, understand, and remember.
Figure 1.2: two types of GRIPs. The signs show the traffic network, position and severity of congestion, travel time, destinations, and road numbers. The traffic network is integrated into the traffic sign and cannot be changed.
Source: Public Works and Water Management Department, Centre for transport and navigation (Rijkswaterstaat, Dienst Verkeer en Scheepvaart).
Figure 1.3: an FCIP positioned over the motorway.
While an FCIP can provide more information than a VMS and has more graphical possibilities than a GRIP, there is a risk that more information may be provided than drivers can actually process. The designers of travel information must tread a fine line between providing as much useful information as possible while minimising the risk of information overload. Information overload may result in safety issues and impairment of information processing, particularly, in situations that impose considerable demands on driver's attention, such as high-density traffic. Therefore, it is important to examine how en-route information should be presented to the traveller in order to optimise the effect on route and mode choice. This is the main aim of this thesis.
Chapter 1 - Congestion and information provision 11
The research reported in this thesis was conducted within the AMICI-project (an acronym for
Advanced Multi-agent Information and Control for Integrated multi-class traffic networks),
part of the Dutch program “Verkeer en Vervoer” (Traffic and Transport) funded by Connekt/NWO. Within the program, strategies to mitigate congestion are examined based on a combination of behavioural change, efficient use of existing infrastructure, and efficient land use.
Within the AMICI-project, methods for an optimal assignment of cars over available routes by means of Dynamic Travel Management are examined. The focus is on the (optimal) coordination between different, otherwise isolated, Dynamic Travel Management measures and the provision of traffic information that anticipates expected future conditions. For example, it aims to jointly develop models that indicate how the travel network may be used more efficiently and help providing information on position and severity of traffic congestion on available routes. Subsequently, models are developed to measure current travel flows, and predict traffic flow in the near future, taking into account traffic from different networks. Traffic flow models developed within the AMICI-project are described in Ngoduy (2006). These models provide current travel times within a traffic network. Such models also take into account changes in network characteristics due to information provision (Van den Berg et al., 2005). Within the scope of this thesis, research on the design of optimal travel information will be reported. Subsequently, the behavioural response to travel information and effects on traffic flow are examined. As a result, more effective and more accurate information may become available to help travellers make optimal and reliable route choices.
This thesis focuses on the question of how to effectively design complex dynamic travel information so that it can be optimally used by travellers. Particularly, the effects will be explored of designs that combine a route map with colours to indicate the position and severity of congestion. The focus is on the design of the information itself, and also on how travellers interpret and deal with the information that is provided. Therefore, first, cognitive and ergonomic guidelines are reviewed that facilitate travellers to read and comprehend the information provided. Second, from a social psychology point of view, this thesis reviews reasons why - in spite of the provision of well-designed information - travellers may or may not take a given advice on board, and why travellers sometimes choose a suboptimal travel option. Next, based on these ergonomic and psychological principles, empirical work is presented that provides more insight into which factors improve the design of travel information, i.e. that will encourage travellers to elaborate (more) on the information that is provided and help them make better informed choices when they travel.
In the next chapter cognitive ergonomic guidelines for the design of an FCIP are reviewed. Subsequently, a framework for information provision is introduced that may optimise the use of the information and therefore the effect of the dynamic travel information on route choice, mode choice, and congestion.
13
2
Travel information to mitigate congestion
Chapter 1 showed that travel information as displayed by means of an ATIS can encourage travellers to use the travel network more efficiently. In the current chapter, the guidelines for designing ATIS are discussed. Furthermore, based on social psychological research, an overview will be given of possible reasons why travellers may not always take a given advice on board, and it will explore the reasons why travellers sometimes choose a suboptimal travel option, despite the provision of well-designed information. Subsequently, guidelines are presented based on cognitive ergonomic and social psychological principles to help improve the (future) design of travel information on a Full Colour Information Panel FCIP.
2.1
Diversion rate
Not all travellers may have the option to deviate from their route or travel mode choice. For example, a change in routes may not be an option when arrangements have been made to meet someone at a certain location along a route. Also, a change in travel mode may not be an option when travelling with heavy luggage, when visiting several addresses during a trip, or when the return trip is at a time when public transport is not available. Travellers who do have the possibility to change their travel mode or route are referred to as choice travellers. If this specific group of travellers would change their travel behaviour, congestion may be mitigated significantly. For example, if 20% of the travellers make a choice that is beneficial for the travel network (e.g. a choice that helps to maintain or recover the equilibrium within the network) traffic flow will improve significantly. In general, it is assumed that a small change in traffic intensity during peak hours may lead to a free flow situation on roads where traffic intensity equals road capacity. This occurs during holidays. The total amount of congestion during peak hours during the holidays decreases significantly due to the fact that fewer commuters have to go to work.
Therefore, it is worthwhile to encourage choice travellers to make a choice that is beneficial for the travel network. ATIS may facilitate the information provision to these travellers. Whether ATIS have an impact on the behaviour of choice travellers and consequently, on the travel network, depends on the outcomes of travel decisions in response to the information provided (Polydoropoulou & Ben-Akiva, 1999). ATIS should be capable of reducing traffic flows by means of information that encourages drivers to divert from their regular routes (Khattak et al., 1993) or travel modes. However, although travellers tend to appreciate traffic information about possible route choices, they hardly change their travel behaviour accordingly (Noonan & Shearer, 1998). That means that travel information in these cases may not be designed optimally.
The effect of ATIS is measured by means of the diversion rate: the difference between the percentage of drivers that use alternative routes or travel modes suggested by ATIS, and the percentage of drivers that use alternative routes or travel modes when the ATIS provides no information. For a more efficient use of the travel network during congestion or when congestion is developing, the diversion to alternative routes or alternative travel modes may increase as a result of information provision. As such, individual drivers may be persuaded to divert to an alternative route.
Research in recent years has shown that the diversion rate from the intended route depends mostly on three factors: traffic situations, driver characteristics, and content of the information provided. The effect of these three factors will be explained next. Subsequently, additional reasons for this occurrence will be explored.
The traffic situation is the first factor that may have an effect on the diversion rate. That is to say, travellers will consider whether to change to an alternative route or travel mode is worthwhile given the traffic situation within the travel network (Chatterjee & McDonald, 2004). Local circumstances during normal traffic conditions (e.g. relative journey times) (Wardman et al., 1997), type and distance of the alternative routes (Emmerink et al., 1996; Schiesel & Demetsky, 2000), and cause and extent of the delay (Wardman et al., 1997) may all have an effect on the choice to change to an alternative route.
Route guidance via ATIS is most effective when the route advice provides information on situations that are different from normal, because traffic conditions in that case are unpredictable to travellers (Chatterjee & McDonald, 2004). That is, the effect of ATIS on route diversion is larger in case of non-recurrent incidents (i.e. accidents and temporary closure of road segments) than in case of recurrent congestion warnings (Levinson & Huo, 2003). For non-recurrent congestion, diversion rates between 10 and 40% are reported (Mammar et al., 1996; Chatterjee et al., 2002; Erke, Sagberg & Hagman, 2007). For messages reporting recurrent congestion without instructions on how to proceed the journey, diversion rates between 2 and 5% are reported (Chatterjee et al., 2002). Apparently, most travellers do not change their intended route during recurrent congestion. Moreover, information acquisition via ATIS rarely leads to a shift in travel modes (Peirce & Lappin, 2003). Most studies report a mode change around 1%.
The second factor that influences the diversion rate are driver characteristics, such as age, sex, and experience with the travel network (Wardman et al., 1997). Experienced travellers may think of better alternative routes than advised (Chatterjee & McDonald, 2004). In a study conducted in Oslo, a Variable Message Sign indicated a closed road segment and a recommended alternative route. Only 20% of the travellers followed the recommended advice. However, virtually none of the travellers arrived at the closed road segment. Probably,
