Transcript of "Transportation and Spatial Modelling: Lecture 1"
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1CIE4801: What for, what, and how17/4/13Challenge the futureDelftUniversity ofTechnologyCIE4801 Transportation and spatial modellingRob van Nes, Transport & PlanningWhat for, what, and how?
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2CIE4801: What for, what, and howTopic of this course• Transportation and spatial modelling• Theory• Concepts• Algorithms• Application• Focus on HOW it is done today• Don’t let that stop you from being critical• Focus on how it is might be done tomorrow:• CIE5802-09 Advanced transportation modelling
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3CIE4801: What for, what, and howCourse materialCourse material:Lecture notes Transportation ModelingRecommended material:Ortuzar, J. de Dios, L.G. Willumsen (2011), Modellingtransport 4th edition, John Wiley & Sons, ChichesterRecommended articles on spatial modelling:Wegener M., F. Fürst (1999), Land-use transport Interaction: Stateof the art, Berichte aus dem Institut für Raumplanung 46,Universität DortmundSchoemaker A., A. van der Hoorn (2004), LUTI modelling in theNetherlands: Experiences with TIGRIS and a framework for a newLUTI model, European Journal for Transportartation andInfrastructure Research, Vol. 4, No. 3, pp. 315-332Zondag B, G. de Jong (2011), The development of the TIGRIS XLmodel: a bottom-up approach to transport, land-use and theeconomy, Research in transportation economics 31, pp. 55-62Blijie, B., J. de Vries (2006) , What, Where, and Which? Nested LogitModel for Dutch Housing Choice, Paper presented at the AnnualMeeting of the Transportation Research Board, TRB, WashingtonDe Bok, M. (2007), Estimation and Validation of a Microscopic Modelfor Spatial Economic Effects of Transport Infrastructure,Transportation Research Part A: Policy and Practice, Volume 43,Issue 1, Pages 44-59
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4CIE4801: What for, what, and howExercises in Omnitrans 6.0http://www.omnitrans-international.comFor more information on Omnitrans and it’s tutorial see:
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5CIE4801: What for, what, and howContent• What for?• What?• How?• How? Modelling choices• Resumé
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7CIE4801: What for, what, and howSimilarity between travelling andtransportation modelling?• You don’t travel just for fun, but to perform an activity somewhere• Note that travelling can be fun as well!• You don’t model the transport system just for fun, but for a purpose• Note that modelling transport systems can be fun as well!
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8CIE4801: What for, what, and howWhat would you like to know?Input Model Output?
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9CIE4801: What for, what, and howPossible answers• Traffic flows on links and/or line occupancy• For design purposes• Traffic engineering, Business case• For assessment purposes• Economic, Environmental, Safety• For traffic management studies• Network/system performance• Vehicle kilometres (per road type)• Modal split (per trip type)
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10CIE4801: What for, what, and howWhy would you like to know this?• Because you’re considering a measure• To build a road• To add a lane• To change a public transport network• To develop a residential/industrial area• To change a one-way street system• To introduce a pricing policy• Because you want to understand a situation or a problem• Congestion• Pollution• Noise• Accessibility• Because of legislation• Air quality
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11CIE4801: What for, what, and howMain goal of transportation andspatial models• To provide quantitative information of the transportation andspatial system for the analysis of possible future situations• Key tool for decision making processes for the transportation andspatial system
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12CIE4801: What for, what, and howTransportation planning processProblemObjectivesAssessmentcriteriaDesign ofsolutions, plansEvaluation ofsolutionsAnalysis ofsolutions=Prediction ofsolutionsDecisionCongestionEnvironmentAccessibilityCongestion standardsEnvironmental standardsModelCBAMCA
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13CIE4801: What for, what, and howEnvironmentalalternativePublic transportalternativeInfrastructurealternativeFuture situationZero alternativePlanningalternativesAlternative AAlternative BAlternative CCurrentsituationEvaluation of transportation plans
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15CIE4801: What for, what, and howWhat should be in the black box?Or when would you say that the black box is OK?Input Model Output
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16CIE4801: What for, what, and howPossible answers• Proper representation of the transportation systemorCapture the key mechanisms of the system• Theoretically underpinned• Empirically validated• As simple as possible, but not simplerHow?
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17CIE4801: What for, what, and howProper representation?• Decomposition in relevant components• Model mechanisms within components• Model relationships between components• Note that these relationships are most likely• Non-trivial• Non-linear• Imply many feedback mechanisms
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18CIE4801: What for, what, and howMain mechanism for thetransportation and spatial systemTransport system(transport and trafficservices)Accessibility(ease to reach alocation)Land use(spatial planning)Activities(living. work.recreation)
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19CIE4801: What for, what, and howWhat are the components of thetransportation system?
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20CIE4801: What for, what, and howWhat are the components of thespatial system?
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21CIE4801: What for, what, and howChoicedestina-tionChoicemodeChoiceroute/timeTravel time& costsAccessibilityAttractivenessChoicelocationinvestorsBuildChoicelocationusersMoveActivitiesAbility totravelChoicetripMechanism in more detail:Wegener’s circle
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22CIE4801: What for, what, and howTravel choice model systemtrip production /trip attractiontrip distributionmodal splitperiod of dayassignmenttrip frequencychoicedestinationchoicemodechoicetimechoiceroutechoicetravel timesnetwork loadsetc.
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24CIE4801: What for, what, and howPreviously mentioned topics• Theoretically underpinned• Empirically validated• As simple as possible, but not simpler
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25CIE4801: What for, what, and howTheoretically underpinned?• Descriptive models• Mathematical relationship between input and output• Statistics• Analogy• Models based on Choice Theory• Utility maximisation• Logit modelling• Equilibrium concept• E.g. route choice: 10 minutes versus 15 minutes…….
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26CIE4801: What for, what, and howDevelopment process of a modelHypothesesTheoryConceptualmodelEmpiricalmodelValidatedmodelObservations PhenomenonDecisionproblemEstimation/calibrationTesting/verificationModelapplication
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27CIE4801: What for, what, and howEmpirically underpinned?• What kind of data are you thinking of?• Data to build a model• Data to validate a model
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28CIE4801: What for, what, and howWhat is the input you need?Input Model Output
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29CIE4801: What for, what, and howTypical types of input• Transport system• Road network• Public transport services• Transport policy• Spatial system• Inhabitants, jobs, facilities• Environment• Economic system
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30CIE4801: What for, what, and howWhen is a model valid?Current practice:• State of the art techniques• Well established software• Based on available dataBottom line in practice:• When the model reproduces observed flows
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31CIE4801: What for, what, and howHow to simplify the system?• 16.7 million inhabitants (plus x visitors from abroad)• 7.5 million households• 7.2 million houses• 750 thousand companies• x reasons for travelling• 365 ¼ days per year• 24 hours per day• 7.9 million cars• 10.6 million vehicles• 138 thousand kilometre road• 3 thousand kilometre rail
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32CIE4801: What for, what, and howPossible simplifications• Aggregation to groups• Persons, trip type, geographical• Selection of a period and/or day• Average pattern!• Selection of trip purposes• Selection of modes• Selection of network detail• Selection of processes/components
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33CIE4801: What for, what, and howExample zoning system
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34CIE4801: What for, what, and howTravel choice model systemTrip production /Trip attractionTrip distributionModal splitPeriod of dayAssignmentZonal dataTransportnetworksTravelresistancesTrip frequencychoiceDestinationchoiceModechoiceTimechoiceRoutechoiceTravel timesnetwork loadsetc.
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35CIE4801: What for, what, and how4How?: Modelling choices
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36CIE4801: What for, what, and howTheory choice behaviourHomeikZBeach: kUilZIKEA: lUimZLeisure park: mU
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37CIE4801: What for, what, and howBeach IKEA Leisure parkUtility maximisationUUi = 0Uk Ul UmZik ZilZimUk - Zik Ul - Zil Um -Zim
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38CIE4801: What for, what, and howChoice theory: Utility maximisation• Main assumptions• People make choices• They maximise their personal utility (within their constraints)• Thus not just minimisation of travel times!• People have set of (feasible) alternatives having utility (anddisutility)• People opt for alternative having the highest net utility• NB. What happens when the net utility is negative?
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39CIE4801: What for, what, and howTravel choice theoryTravel behaviour is not always logical at first sight• large detours just to avoid parking costs• waiting times are usually over-estimated:– waiting at the train station– waiting in front of a traffic light– waiting in a congestion queue• costs for driving a car may seem less expensivethan a train ticketIt is all about the perceptions that travelers have
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40CIE4801: What for, what, and howDiscrete choice theoryDefinitions:Each alternative i has an objective/observable utilityEach individual faces a subjective non-observed utilityfor each alternative i.iVi i iU V ε= +iεUtility of alternative i for each individual:Behavior:An individual will choose alternative i if this alternativehas the highest utility, i.e. iffor alli jU U j≥
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41CIE4801: What for, what, and howDiscrete choice theory( for all )i i jp P U U j= ≥( for all )i i j jP V V jε ε= + ≥ +( for all )j i i jP V V jε ε= − ≤ −Probit-model.ip =KeeijVi Vjpµµ=∑Logit-modelIf ’s are allGumbel distributed(independent, withscale parameter ),iεµIf ’s are allnormally distributed(independent),iε
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42CIE4801: What for, what, and howLogit modelAlternatives to choose: i = 1, 2, 3. ...What is the probability to choose alternative i ?or:Which share of travellers chooses alternative i ?
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43CIE4801: What for, what, and howLogit model: main principle• Each alternative has measurable attributes ( )• These attributes have their own perception ( )• Not everything is measured or objective ( )• For each alternative the ‘(dis-)utility’ is the weighted sum of theattributes plus an error termxiAi i x xixU V c Aε ε= + = ⋅ +∑xcε
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44CIE4801: What for, what, and howUtility and disutility:Weighted sum of attributes• Route choice car:c1*time + c2*costs => time*c1/c2 + costs = time*VOT + costs• Route choice urban PT:2.2*Ta+1.5*Tw+Ti+2.3*Twt+5.9*Nt+1.1*Te• Mode choice:additional attribute for preference for specific modes• Destination choice:additional attributes describing attractiveness location
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45CIE4801: What for, what, and howValue of time (€/h)Commuting Business Rest TotalCar 8.83 28.58 5.69 9.22Train 8.31 17.59 5.12 6.55Bus and tram 7.86 13.44 4.90 5.75All modes 8.20 27.56 5.47Price level 2006
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46CIE4801: What for, what, and howLogit model: Formula• Logit formulation assumes independent alternatives• Parameter represents the sensitivity for differences in utility• High value: crisp choice; Low value: uniformly distributedeeijVi Vjpµµ=∑µ
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47CIE4801: What for, what, and howShape of logit function= probability for choosing alternative iipipiV01Logit modeleeijVi Vjpµµ=∑
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48CIE4801: What for, what, and howImpact of the scale parameter1p1V01.02V0.50.1µ =1=µ10=µThe lower the scale parameter , the higher thevariance or ‘spread’ in the choice proportions.µ
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49CIE4801: What for, what, and howScale parameter and distribution1V 2V1µ1( )P U U=10µ =2( )P U U=1µ =0.1µ =
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50CIE4801: What for, what, and howExample: tollExtension A4route Aroute BSchiedam - Den Haagroute A: 20 min. + € 2route B: 35 min.(dis)utility function:Vi = -[time + 5 * toll]µ = 0.1/minPA = 62%
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51CIE4801: What for, what, and howEffect of constraintsPT shareTravel time car– Travel time PT100%0%Car captivesPT captives
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52CIE4801: What for, what, and howSome comments on logit• Logit is commonly used, but isn’t perfect• Logit is sensitive for differences between utilities, independent ofthe absolute value of the utility• Logit assumes independent alternatives• Route overlap• Red/Blue bus problem
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54CIE4801: What for, what, and howResumé• Modelling is a tool in a decision process• Decision process sets requirements• Modelling focuses on transport system• When relevant spatial system is included as well• Modelling is simplifying the system• Zones, specific period(s), specific trip purposes, selection of networks• Most of all selection of processes
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55CIE4801: What for, what, and howTravel choice model systemtrip production /trip attractiontrip distributionmodal splitperiod of dayassignmentzonal datatransportnetworkstravelresistancestrip frequencychoicedestinationchoicemodechoicetimechoiceroutechoicetravel timesnetwork loadsetc.
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56CIE4801: What for, what, and howCourse scheduleLecture 2 Trip generationNetworksLecture 11 Case study DelftExam questionsLecture 3 Trip distribution Lecture 12 Dutch national modelBase year matrix estimationLecture 4 Mode choice Lecture 13 Regional Model applicationUrban transport modellingLecture 5 Time of day choiceExam questionsLecture 14 Discussion models inpractice, Exam questionsLecture 6 Assignment Lecture 15 Spatial Modelling: conceptand descriptive modelsLecture 7 Congested assignment Lecture 16 Spatial modelling: Land useand transportation modelsLecture 8 Assignment: special topics Lecture 17 Beyond the 4-step modelLecture 9 OD-matrix estimation Lecture 18 Exam questionsLecture 10 4-step model repriseForecasting
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